TABLE OF CONTENTS

LIST OFTABLES........................................................................................................................................... iv
LIST OF FIGURES ......................................................................................................................................... v
1. INTRODUCTION ....................................................................................................................................... 1
1.1 Aim ............................................................................................................................................. 1
1.1.1 Specific objectives...................................................................................................................... 1
1.2 Structure of the Technical Report............................................................................................... 1
2. ENGINEERING DESIGN OF KIBP ROADS ............................................................................................. 3
2.1 INTRODUCTION........................................................................................................................ 3
2.2 LEADING ROLE PERFORMED ................................................................................................. 3
2.3 PROJECT COORDINATION...................................................................................................... 4
2.4 ASSESSMENT OF SUBGRADE STRENGTH ........................................................................... 5
2.4.1 CBR Field Measurements. ......................................................................................................... 5
2.4.2 Field sampling and Laboratory Testing. ..................................................................................... 6
2.4.3 Review of Laboratory Soil Test Results. .................................................................................... 8
2.4.4 Comparison of the DCP CBR Test results With Laboratory CBR test results. ........................... 8
2.4.5 Selection of Design CBR ............................................................................................................ 8
2.5 TRAFFIC SURVEYS. ANALYSIS, AND PREDICTION ............................................................ 10
2.5.1 Manual Classified Traffic Counts.............................................................................................. 10
2.5.2 Derivation of full day Traffic Flows/ADT ................................................................................... 12
2.5.3 Derivation of AADT .................................................................................................................. 13
2.5.4 Conversion of AADT to Pcu/day............................................................................................... 13
2.5.5 Estimation of Design Traffic Volume ........................................................................................ 14
2.5.5.1 Traffic Prediction to Estimate Design Volume. ......................................................................... 14
2.5.5.2 Diverted Traffic ......................................................................................................................... 15
2.5.5.3 Generated Traffic ..................................................................................................................... 15
2.5.5.4 Combined AADT1 ..................................................................................................................... 15
2.5.5.5 Traffic growth. .......................................................................................................................... 16
2.5.5.6 Design Volume/ Capacity (AADT15) ......................................................................................... 16
2.5.6 Estimation of Design Traffic Loading........................................................................................ 17

i
2.5.6.1 Traffic Prediction ...................................................................................................................... 17
2.5.6.2 Selection of Appropriate Damage Factors................................................................................ 18
2.5.6.3 Conversion of Traffic flows to cumulative total ESAs in each direction .................................... 19
2.5.6.4 Determination Total ESAs ........................................................................................................ 19
2.5.6.5 Selection of Design Traffic Loading Class ................................................................................ 20
2.6 CONSTRUCTION MATERIALS INVESTIGATIONS. ............................................................... 21
2.6.1 Material Type and Suitability. ................................................................................................... 21
2.6.2 Material Sources. ..................................................................................................................... 21
2.6.3 Material Properties and Suitability for use in the pavement layers. .......................................... 23
2.7 GEOMETRIC DESIGN............................................................................................................. 25
2.7.1 Functional Classification. ......................................................................................................... 25
2.7.2 Design Speed........................................................................................................................... 26
2.7.3 Design Vehicle. ........................................................................................................................ 26
2.7.4 Cross sectional Elements. ........................................................................................................ 26
2.7.5 Horizontal Alignment Details .................................................................................................... 27
2.7.6 Vertical Alignment Details ........................................................................................................ 28
2.7.7 Engineering Safety Measures .................................................................................................. 31
2.7.8 Design Drawings ...................................................................................................................... 31
2.8 PAVEMENT DESIGN............................................................................................................... 32
2.8.1 Design Variable/Parameters .................................................................................................... 32
2.8.2 Design Process. ....................................................................................................................... 32
2.8.3 Pavement Alternative Based MoWT (2010) Guidelines ........................................................... 32
2.8.3.1 Traffic Loading Class ............................................................................................................... 33
2.8.3.2 Subgrade Strength design Class.............................................................................................. 33
2.8.3.3 Nominal Operating Conditions ................................................................................................. 33
2.8.3.4 Selection of Pavement Structure alternative. ........................................................................... 33
2.8.3.5 Availability of constructional materials ...................................................................................... 34
2.8.3.6 Pavement Structure Number. ................................................................................................... 34
2.8.4 Pavement Alternative Based Overseas Road Note 31 (ORN31) Guidelines............................ 36
2.8.5 Pavement Alternative structure number ................................................................................... 36
2.8.6 Cost Considerations. ................................................................................................................ 36

ii
 2.8.7 Recommendations on the Final Design alternative .................................................................. 37
2.9 HYDROLOGY AND DRAINAGE DESIGN ............................................................................... 38
3. SUPERVISION OF ROAD PERIODIC MAINTENANCE. ........................................................................ 39
3.1 INTRODUCTION...................................................................................................................... 39
3.2 SITE SUPERVISION AND CONTRACT MANAGEMENT ROLES ........................................... 39
3.3 WORK INSPECTIONS AND APPROVALS.............................................................................. 40
3.4 MOBILIZATION AND PERFOMANCE OF RESOURCES........................................................ 46
3.5 ASSESSMENT OF MATERIALS’ TEST RESULTS. ................................................................ 47
3.6 ASSESSMENT OF COMPLETED WORK SECTIONS’ TEST RESULTS. ............................... 47
3.7 ASSESSMENT OF VARIATIONS IN QUALITY ....................................................................... 47
3.8 ISSUANCE OF SITE INSTRUCTIONS. ................................................................................... 47
3.9 ASSESSMENT OF CLAIMS FOR CONTRACT VARIATIONS. ............................................... 48
3.10 MONTHLY PROGRESS SITE MEETINGS .............................................................................. 49
3.11 PROJECT REPORTING. ......................................................................................................... 49
3.12 MEASUREMENT AND PAYMENTS ........................................................................................ 50
3.13 REVIEW OF THE CONTRACTOR’S WORK PROGRAM AND THE PROGRAM UPDATES .. 51
3.14 CROSS CUTTING ISSUES. .................................................................................................... 51
4. CONCLUSIONS AND RECOMMENDATIONS. ...................................................................................... 55
5. LESSONS LEARNT ................................................................................................................................ 56
BIBLIOGRAPHY .......................................................................................................................................... 57
APPENDICES .............................................................................................................................................. 58
Appendix 2A: Project Implementation Plan.............................................................................................. 59
Appendix 2B: Project Monitoring Tool (Action Register) ........................................................................ 60
Appendix 2C: Test Results from the DCP CBR Evaluation. .................................................................... 61
Appendix 2D: Design Charts, and Charts for estimation of Parameters. .............................................. 62
Appendix 2E: Proposed Culvert Schedule for KIBP. ............................................................................... 63
Appendix 2E: Proposed Side Drain Cross section, Design Considerations, and Schedule. ............... 64
Appendix 2F: Detailed Design Drawings. ................................................................................................. 65
Appendix 3A: Works Contract between UNRA and EIL........................................................................... 66

iii
LIST OFTABLES
Table 1: Structure of the Report....................................................................................................... 1
Table 2: Summary of Standards used in the Laboratory testing of soil samples ............... 6
Table 3: Subgrade Design classes (MoWT, 2010) ............................................................................. 9
Table 4: Selected Subgrade Classification for each of the project Roads............................................. 9
Table 5: Daily Traffic for direction A and Direction B ........................................................................ 11
Table 6: Computation of Night Expansion Factors (NEF) ................................................................. 12
Table 7: Computation of ADT ........................................................................................................ 12
Table 8: Computation of AADT in terms of Passenger Car Units (PCUs) ........................................... 13
Table 9: Design Considerations adopted for estimation of generated Traffic ...................................... 15
Table 10: Computation of generated traffic within the Industrial Park ................................................ 15
Table 11: Baseline AADT in Cognisance of Diverted traffic and Generated Traffic ............................. 16
Table 12: Traffic growth rates in percentages for the three user classes and growth periods ............... 16
Table 13: Estimations of AADT15 in PCUs/Day................................................................................ 16
Table 14: Estimation of Future Commercial Vehicles (DT) ............................................................... 18
Table 15: Mean Vehicle Equivalency factors for each vehicle class as adopted from design reports by
other Consultants ......................................................................................................................... 19
Table 16: Computation of ESAL .................................................................................................... 19
Table 17: Traffic Classes .............................................................................................................. 20
Table 18: Material Sources identified within and outside the project. ................................................. 21
Table 19: Materials Recommendations on suitability for Pavement layers ........................................ 23
Table 20: Road Design Classes adopted from Table 4-2a of MoWT Geometric Design Manual, 2010 . 25
Table 21: Physical Dimensions adopted for the Design Vehicle. ....................................................... 26
Table 22:Design Physical Dimensions for KIBP Roads Cross Section. .............................................. 26
Table 23: Design Standard and Recommendations considered for Horizontal alignment design .......... 28
Table 24: Design Criteria for Horizontal Alignment .......................................................................... 28
Table 25: Design Standard and Recommendations considered for Vertical alignment design .............. 29
Table 26: Design Criteria adopted for vertical alignment design of KIBP roads alignment ................... 30
Table 27: Traffic Class Adopted for all the project roads .................................................................. 33
Table 28: Pavement Alternative (MoWT, 2010) ............................................................................... 33
Table 29: Structural Numbers for the pavement alternatives............................................................. 35
Table 30: Pavement alternative (ORN31) ....................................................................................... 36
Table 31: Pavement structure number (ORN31) ............................................................................. 36
Table 32: Construction estimates for construction works .................................................................. 37
Table 33: Recommendations on Final Pavement Design Alternative ................................................. 37
Table 34: Quality and Quantity progress Inspection activities and Objectives. .................................... 41
Table 35: Equipment and Personnel mobilized by the contractor to project completion. ...................... 46
Table 36:Personnel Mobilized by the contractor to completion of the project ...................................... 46
Table 37: Details of project reports prepared throughout the contract period. ..................................... 49
Table 38: Roles performed in Implementation of Measures that satisfactorily addressed the Cross
cutting Issues............................................................................................................................... 51

iv
LIST OF FIGURES
Figure 1: Road network in KIBP Park ............................................................................................... 3
Figure 2: Project Organogram ......................................................................................................... 4
Figure 3: Conduction of DCPs in the field as witnessed by me. ......................................................... 6
Figure 4: Layout of the predetermined Trial Pit testing locations. ........................................................ 7
Figure 5: Excavation of trial pits for field sampling under my supervision ............................................. 7
Figure 6: Progress photographs for the soil and materials investigations activities.............................. 22
Figure 7: Progress Photographs for Quantity and Quality Progress Inspection Activities ..................... 45

v
1. INTRODUCTION
Uganda Institution of Professional Engineers (UIPE) is a qualifying body for those seeking registration
under Engineers Registration Board (ERB). UIPE carries out professional review of applicants wishing
to become corporate members (Registered Engineer) after minimum of 4 years of their post graduate
experience. The review criteria require that the applicant submits a technical report among other
requirements to demonstrate competence as a potential member. It’s against the requirement that I
have prepared a technical report to describe my involvement in the following projects executed during
my employment at KKATT Consult Limited (KKATT) – An Engineering Consultancy firm in Uganda.
1.1 Aim
The report describes my involvement in each of the following projects in which I played a major part,
including taking the lead in some or all the elements.
 Consultancy Services for the Engineering Design and Tender Documentation for the
Access Roads in the Kasese Industrial and Business Park (KIBP).The project started in
October 2014 to October 2015.
 Consultancy Service for Supervision of Periodic Maintenance of Katunguru - Ishasha Road
(87km). The project started in November 2011 and ended in October 2014 including 6 months
Defect Liability Period.
1.1.1 Specific objectives
The aim of the report has been achieved by clear detailed indication of the following:
 The major roles I played in the Planning, Execution, Monitoring, and closure phases of projects’
Management Life cycle.
 The background to the important decisions for which I was responsible or to which I made a
significant contribution in the implementation of the projects.
 Where I have exercised independent engineering and professional judgment during the
performance of the major roles.
1.2 Structure of the Technical Report
The structure of the Technical Report is indicated in Table 1:
Table 1: Structure of the Report
Section Section Title Discussion
Numbe
r
1 Introduction The section discusses the background to the report and the projects, the aim and
specific objectives of the report, and the structure of this technical report.
2 Preliminary and Gives the back ground to the project, Brief description of the planned project objectives;
Detailed Engineering Indication of the project implement team including the project organogram; Summary of
Design KIBP Roads the leading roles that I performed; Description of the roles I performed and how each of
Network: the role contributed to the achievement of the planned project objectives.
3 Supervision of Road Briefly describes the back ground to the supervision project; Brief description of the
Periodic planned project objectives; position held in the supervision team; Summary of the
Maintenance Works: leading roles that I performed; Description of the roles I performed and how each of the
role contributed to the achievement of the planned project objectives.
4 Conclusions and Summarizes the conclusions and recommendations from the performance of the leading
Recommendations: roles in the implementation of the respective projects as described in section 2 and 3 all

1
Section Section Title Discussion
Numbe
r
in accordance with the registration requirements stipulated by UIPE and ERB as the
Engineers registration organizations in Uganda.
5 Lessons Learnt: The section briefly describes the lessons learnt from the experience in the
implementation of the respective projects.
6 Bibliography. The section lists the sources used for literature review and hence back ground for the
important decisions made.
7 Appendices The section includes all the information used in the performance of the tasks as
appropriately referenced in the report sections

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2. ENGINEERING DESIGN OF KIBP ROADS
2.1 INTRODUCTION
The section describes the leading roles that I performed in the Preliminary and Detailed Engineering
design of 7.8km of new build roads associated with the Kasese Industrial Business Park (KIBP) Master
Plan layout shown in the figure1

Figure 1: Road network in KIBP Park

2.2 LEADING ROLE PERFORMED

KKATT Consult appointed me as the Project Coordinator and Highway Engineer on the project
implementation team as indicated in the organogram in figure 2. Accordingly, I performed the following
leading roles under the supervision of the project team leader, Engineer Kato Kagga:
 Coordination of the project activities including planning, monitoring and control;
 Supervision of alignment Soil surveys and assessment of soil strength;
 Supervision of Traffic surveys, Analysis of traffic data, Estimation of design traffic flows and
traffic loading;
 Location and choice of materials for pavement design;
 Production of Geometrical design for KIBP roads’ network including production of the resulting
design drawings;
 Structural design of Pavement proposed for KIBP roads alignment

I have discussed the tasks performed and background to the decisions made in the following sub
sections of section 2.

3
Figure 2: Project Organogram

2.3 PROJECT COORDINATION

I executed the coordination activities of planning, monitoring, and controlling to ensure achievement of
the clients’ objectives in a timely and cost effective manner including submission of deliverable reports.
For instance, I prepared the implementation plan that internally guided the execution of the detailed
design of the KIBP road network. I prepared the implementation plan through the following steps:
 I broke the whole project into activities which were more manageable components of the
project.
 I allocated appropriate time and estimates of personnel and equipment needed for each of
project activities;
 I defined the logical relationships between the project activities;
 I development the implementation schedule determining how the activities were to be carried
out with a clear indication of their completion date.
 Finally, I developed the project implementation budget indicating the expected expenses.
Consequently, I generated the implementation plan attached in appendix 2A from the planning process
using MS Office Project as the computer aided planning software.

The Monitoring and controlling roles carried out where aimed at regularly measuring and monitor the
project implementation progress to identify variances and allow for timely preventive action whenever
necessitated. Prior to start of the implementation, I developed a monitoring tool (Tracking Ghantt)
attached in appendix 2B which I used to track the actual project implementation progress against the
planned progress objectives as set out in the implementation plan.

In addition, throughout the project execution, I inspected the works of the rest of the team members in
the field, and reviewed their field reports to ensure satisfactory quality of reports from the respective
team members.

At all times, I kept the team informed about project status and issues that could potentially impact client
relations and projects progress. For instance, I emphasized importance of timely submission of
respective expected deliverables and over communication throughout the execution phase as well as
utmost quality of deliverables and field data.

4
2.4 ASSESSMENT OF SUBGRADE STRENGTH
Sub-grade is defined as the potion right below the pavement prepared to standard specifications to
attain specified strength. As recommended by ORN31 and MoWT (2010), I considered subgrade
strength in terms of California Bearing Ratio (CBR) as the most important factor which controlled
structural pavement design for KIBP road network. CBR as the parameter used in pavement design
represented the resistance that can be mobilized by sub grade soils, and was evaluated both in the field
using Dynamic Cone Penetrometer (DCP) and also in the laboratory. In context, I performed the
following leading roles, which ensured performance of the CBR evaluation activity by KCML within the
prevailing testing standards.
 Supervised the CBR field measurement activity;
 Supervision of field sampling;

2.4.1 CBR Field Measurements.

I supervised the Laboratory technicians during Field CBR evaluation to ensure that the test procedure
and methodology used were in accordance with the recommended standards. Therefore, direct
measurement of the subgrade strength in the field was carried out using the DCP Machine. Throughout
the activity, I inspected to ensure the following that validated the test results:
 The testing equipment was in a sound condition .i.e. Cone not worn, rods not bent, and
fasteners tight;
 The DCP testing locations were in accordance with the standard frequency of testing. The DCP
testing was carried out at maximum intervals of 100m to a depth of approximately 1.0 meter
along each of the proposed road alignments (alternating from the Left, Centre and the Right of
the road alignments) all as recommended by MoWT (2010) and TRL (1993);
 The devise was held vertically during tests;
 The hammer was just touching the upper stop prior to release;
 The DCP holes were back filled after testing

The in-situ CBR test results are attached in appendix 2C. Photographs in figure 3 indicate the progress
of the testing activity in the field, under my supervision.
Based on the results and the relevant graphs plotted from the results, I identified the homogenous
sections within KIBP. Homogeneous sections were selected to have the same slope characteristics.
However, the selection of the design CBR was only finalized based on the field test results and the
laboratory test results all as explained appropriately in the sub sections of 2.4.

5
DCP test along Main Commercial road DCP test along Rwenzori Loop road
Figure 3: Conduction of DCPs in the field as witnessed by me.

2.4.2 Field sampling and Laboratory Testing.

The subgrade soils properties on the KIBP network road alignments were evaluated through laboratory
tests on the representative alignment soil samples by KCML under my supervision. In order to ensure
the samples collected were representative of the field conditions, I predetermined the appropriate
standard sampling frequency (refer to figure 4) recommended for pavement design (MoWT, 2010). For
all the KIBP alignment, Twenty Two (22no.) test pits were excavated using manual labour at intervals of
maximum 500 metres to a maximum depth of 1.0metres. Disturbed soil samples were obtained and
taken to the laboratory for evaluation of desirable properties through standard tests. Progress
photographs for the field sampling activity are indicated in figure 5.

Soil strength is dependent on the type of soil, its density, and its moisture content. Accordingly, I
specified the standard tests indicated in table 2 against which KCML priced, and carried out on the
subgrade soil samples using the corresponding standard test methods all recommended within the
MoWT (2010) design framework adopted for the design of the KIBP road network.
Table 2: Summary of Standards used in the Laboratory testing of soil samples
Name of Test Standard Test Method
Moisture content BS 1377: Part 2: 1990
Particle size distribution BS 1377: Part 2: 1990
Liquid Limit BS 1377: Part 2: 1990
Plastic Limit BS 1377: Part 2: 1990
Plasticity Index BS 1377: Part 2: 1990
California Bearing Ratio ASTM: D1883
Soaked CBR ASTM: D1883

6
Figure 4: Layout of the predetermined Trial Pit testing locations.

Excavation of a Test Pit (TP5) along fourth link road Test Pit Excavation at TP 3
Figure 5: Excavation of trial pits for field sampling under my supervision

7
2.4.3 Review of Laboratory Soil Test Results.
Based on the corresponding soil test results from the tests as specified in table 2, I selected the design
CBR input value in consideration of the following design parameters that affect the soils strength and
have a bearing on the performance of the pavement, according the criteria specified by MoWT (2010)
and recommended by TRL (2005).
 Index properties specially the Atterberg limit namely Liquid Limit (LL), Plastic Limit (PL), and
Shrinkage Limit (SL).
 Particle size distribution properties which affect the internal friction and cohesion.
 Degree of compaction which greatly influences soil strength;
 Moisture content which affects the density, cohesion, and internal friction; and confinement. The
project area was considered to be predominantly wet in accordance with the hydrological
surveys and analysis carried out for the project. Therefore, design was based on appropriately
selected CBR values after 4 days soaking to account for the anticipated wet conditions
throughout the design life.
Nevertheless, selection of the design CBR was only finalized after comparison of the DCP-CBR results
with the Laboratory CBR test results.
2.4.4 Comparison of the DCP CBR Test results With Laboratory CBR test results.
I selected the design CBR in subsection 2.4.5 after comparison of the DCP-CBR values with the
Laboratory 4 day’s soaked CBR values. The DCP CBR values were relatively higher for all the road
sections than the laboratory CBR values. This was because of the difference in the moisture and density
test conditions respectively.

The DCP tests were conducted at the prevailing field conditions at the time of testing. The results
therefore don’t take into account variations in such influencing factors like moisture content, local
drainage conditions, and time of the year, weather conditions and others that would potentially fluctuate
throughout the life of the pavement unlike the Lab CBR test results.

The Lab CBR values resulted from simulation of the most likely conditions to occur (nearly saturation)
during the life of the road under anticipated traffic loading. Therefore, the Laboratory soaked CBR
results at 95% MOD AASHTO formed the basis for selection of most appropriate design CBR values.

2.4.5 Selection of Design CBR

I appropriately selected the lowest probable representative CBR likely to occur during the life of the road
as the design CBR that represented the design sub grade soils strength, thus, influencing the structural
pavement design.

As mentioned before, analysis of the DCP CBR results revealed no change in slope along each of the
respective short alignments that formed the KIBP network, thus, homogeneous conditions were
assumed along each of the alignment, also contended by TRL (1993). Therefore, I considered the 4 day
soaked CBR value provided for the one trial pit on each section for design.

Within the MoWT (2010) design frame work, the selected Soaked CBR values were classified according
to the Subgrade strength classes as reproduced in table 3. In table 3.1, TRL (1993) also recommends
for similar strength class within the same range of CBR values.

8
Table 4 indicates the selected design soaked CBR values for each of the proposed road alignment in
KIBP; and the corresponding subgrade strength class as appropriately adopted from table3. With 80%
of the project roads having their CBR in class S4; I objectively adopted S4 as the Design subgrade class
for all the roads in KIBP road network.
Table 3: Subgrade Design classes (MoWT, 2010)
Design CBR % Subgrade Strength Class
<2 S1
2 -4 S2
5-7 S3
8 - 14 S4
15 - 29 S5
30+ S6
Table 4: Selected Subgrade Classification for each of the project Roads
Road Name Design CBR (%) Adopted Subgrade Class.
Main Commercial Street 21 S5
Kasese Industrial Road 12 S4
Rwenzori Loop 23 S5
First Link Road 13 S4
Second Link Road 8 S4
Third Link Road 13 S4
Fourth Link Road 17 S4
Fifth Link Road 17 S4
Civic Link 19 S4
Commercial Lane 13 S4
Access Road 13 S4

The design subgrade strength class together with the traffic class obtained in section 2.5 were then
used with the catalogue of structures to determine the pavement layer thicknesses as appropriately
explained in subsections of 2.8.

9
 2.5 TRAFFIC SURVEYS. ANALYSIS, AND PREDICTION
Traffic loading is the most important external parameter that influences pavement thickness design. The
volume and composition of the current and future traffic needed to be known for the geometrical design
of the KIBP road network alignment and economic analysis. In addition, the number and axle loading of
only the commercial vehicles also needed to be known for structural design of the prospective pavement
for the proposed KIBP road network. Only the axle loading from commercial vehicles was considered
because the damage caused by the small vehicles is insignificant.

Accordingly, I carried out the following activities and established the input values for the respective
traffic related design parameters:
 Supervised the conduction of traffic surveys i.e. Manual Classified Traffic Count surveys and
Axle load surveys from which information on the traffic flows and loading was obtained
respectively;
 Analysed the traffic survey data to determine baseline traffic flows in terms of Annual Average
Daily Traffic (AADT) – an estimate used in traffic analysis as discussed later;
 Appropriately projected the baseline traffic flows to Future AADT in Passenger Car Units per
Day (pcu/day) for input in the geometrical design of the roads;
 Estimated the Design Traffic Loading expressed in Equivalent Standard Axles for input in the
structural design of pavement;
 Appropriately selected the design traffic class corresponding to the estimated traffic loading
anticipated throughout a selected design period/life.

In the following subsections of 2.5, I have discussed in detail, the activities I performed in assessment of
traffic for engineering design of the KIBP roads.

2.5.1 Manual Classified Traffic Counts.

Traffic counts and classifications for the existing Kasese – Mbarara road formed the basis for
forecasting the design traffic volume and design traffic loading. The existing road was selected for traffic
surveys because the proposed project roads are non-existent, and Kasese – Mbarara road happen to
be the only closest existing road in the project area, that to some extent, can be assumed to have
similar traffic characteristics as the project roads as contended by TRL (993).

I successfully supervised the conduction of traffic counts on the road; which enhanced collection of valid
and accurate traffic count data. Throughout the performance of the traffic counts, I inspected to ensure
the following prevailing good practise that minimized errors in the traffic flow data (MoWT, 2010; ORN5)
 Traffic counts were conducted for the planned duration of 16 hours a day for 5 days and 24
hours a day for 2 days, making a total of 7 traffic count days.
 The counts were conducted at the planned count station along the road. Surveys were
conducted at the same location often used by Uganda National Roads Authority for mobile
weigh bridge activities.
 Traffic counts were carried out on normal traffic flow days throughout the planned count
duration.

10
  I coordinated the traffic count activities to ensure that only authorized variations from the
standard requirements were implemented, all as authorized and instructed by the Team leader
in consultation with the client.
 I inspected to ensure that the enumerators recorded each vehicle that passed the count station
in the both directions; and that the data was entered correctly on the survey form in accordance
with the vehicle type.
 Uganda Police was involved to ensure safety and security of during the traffic surveys.
Following the successful completion of the traffic count field surveys, I processed the resulting traffic
count data as indicated in table 5 for each of the directions; Direction A for Kasese-Mbarara direction
and direction B for Mbarara-Kasese direction. The data was tabulated to indicate the classified traffic
flows summed for each of the traffic count day within the counting hours.

Thereafter, I analysed the data as per the technical requirements of the design project to derive the
design traffic related parameters of Average Daily Traffic (ADT) applicable to the traffic count duration of
7days and then the Annual Average Daily Traffic (AADT) defined as the total annual traffic in both
directions divided by 365 as obtained by recording actual traffic flows over the 7 days count period and
application of the relevant adjustments and corrections to estimate the AADT, all as discussed under
appropriate sub sections of 2.5.

Table 5: Daily Traffic for direction A and Direction B

Day Thur Fri Sat Sun Mon Tue Wed Total Night - Night - Sat
Tue
KASESE TO MBARARA DIRECTION (A)
Saloon Cars & Taxis 272 294 396 192 316 255 253 1,978 10 23
Light Goods, Vans & Pickups & 4WD 173 197 199 249 181 148 132 1,279 12 24
Small Bus 63 81 69 69 73 54 64 473 17 23
Medium Bus 1 3 2 8 1 1 1 17 0 0
Large Bus 10 9 10 7 7 6 7 56 3 3
Light Single unit Truck 32 43 41 47 56 49 39 307 4 0
Medium Single unit Truck 57 50 38 33 49 48 43 318 10 13
Heavy Trucks 22 23 4 15 10 6 9 89 10 14
Semi-Trailer &Trailer Trucks 30 48 45 24 41 34 42 264 40 34
Motorcycles 634 824 738 558 710 627 700 4,791 20 16
Total 1294 1572 1542 1202 1444 1228 1290 9,572 66 100
MBARARA TO KASESE DIRECTION (B)
Saloon Cars & Taxis 217 266 346 204 333 279 242 1,887 15 16
Light Goods, Vans & Pickups & 4WD 205 189 177 216 161 178 145 1,271 6 12
Small Bus 76 74 87 63 57 60 52 469 5 3
Medium Bus 0 4 3 3 2 0 2 14 0 0
Large Bus 11 14 11 13 11 11 10 81 2 1
Light Single unit Truck 45 49 38 38 53 44 52 319 0 0
Medium Single unit Truck 57 53 32 21 50 33 38 284 6 5
Heavy Trucks 15 8 20 11 8 8 15 85 1 9
Semi-Trailer &Trailer Trucks 45 43 51 51 36 57 45 328 25 11
Motorcycles 788 771 856 679 812 768 820 5,494 15 9
Total 1459 1471 1621 1299 1523 1438 1421 10,232 60 57

11
2.5.2 Derivation of full day Traffic Flows/ADT
I appropriately adjusted such traffic flow data in table 5 to full day traffic flow data. Accordingly, Table 6
illustrates the derivation of the weekday and weekend Night Expansion Factors derived, and used to
convert the 16 hour count to 24-hour count. These factors were obtained by dividing 24-hour counts by
the average of 16-hour counts for each vehicle category. The 5 day-16hour counts were converted to
24-hour counts by multiplying the average totals per vehicle type category with the appropriate NEF
determined. Subsequently, the ADT was computed in table 7 as the average over seven (7) days of the
derived 24-hour traffic data.
Table 6: Computation of Night Expansion Factors (NEF)
Vehicle category Av. Av. Av. Av. NEF - NEF -
Weekdays Weekend Weekdays Weekend Weekday Weekend
16-hr 16-hr 24-hr 24-hr
counts counts counts counts
Saloon Cars & Taxis 545 569 570 608 1.05 1.07
Light Goods, Vans & 342 421 360 457 1.05 1.09
Pickups & 4WD
Small Bus 131 144 153 170 1.17 1.18
Medium Bus 3 8 3 8 1.00 1.00
Large Bus 19 21 24 25 1.26 1.20
Light Single unit Truck 92 82 96 82 1.04 1.00
Medium Single unit 96 62 112 80 1.17 1.29
Truck
Heavy Trucks 25 25 36 48 1.44 1.92
Semi-Trailer &Trailer 84 86 149 131 1.77 1.53
Trucks
Motorcycles 1491 1416 1526 1441 1.02 1.02

Table 7: Computation of ADT

Vehicle Type Av. Av. Av. Av. NEF - NEF - ADT
Weekdays Weekend Weekdays Weekend Weekday Weekend
16-hr 16-hr 24-hr 24-hr
counts counts counts counts
Saloon Cars & Taxis 545 569 570 608 1.05 1.07 581
Light Goods, Vans &
342 421 360 457 1.05 1.09 387
Pickups & 4WD
Small Bus 131 144 153 170 1.17 1.18 158
Medium Bus 3 8 3 8 1.00 1.00 4
Large Bus 19 21 24 25 1.26 1.20 24
Light Single unit Truck 92 82 96 82 1.04 1.00 92
Medium Single unit
96 62 112 80 1.17 1.29 103
Truck
Heavy Trucks 25 25 36 48 1.44 1.92 39
Semi-Trailer &Trailer
84 86 149 131 1.77 1.53 144
Trucks
Motorcycles 1491 1416 1526 1441 1.02 1.02 1501
Total 2828 2834 3029 3050 - - 3033

12
2.5.3 Derivation of AADT
The ADT in table 7 was corrected for seasonal variations (SF) to derive a better estimate of the current
AADT. SF’s are simply the ratio of the average daily traffic in the month in question and the Annual
average traffic from a full year traffic count data. However, considering the lack of appropriate full year
traffic count data, the ADT flow information determined in table 7 was assumed to be the same as the
current estimate of AADT used in the following sections of 2.5.

However, for geometrical design of road, it was necessary to agglomerate the heterogeneous traffic
stream into a homogenous stream to account for the effect of the various vehicle types hence
adequately design for the geometrical features of the road alignment.

2.5.4 Conversion of AADT to Pcu/day

To take into account the influence of capacity of the different vehicle type mix, the heterogeneous
current AADT derived in table 7 was converted to a homogenous current AADT in terms of Passenger
Car Units (PCU); using the conversion factors recommended by MoWT (2010) for each vehicle type.
PCU is defined as the index of impedance effect of a vehicle on other vehicles, using the car as the
basic unit (Taking the value 1.0). Table 9 indicates the results of the homogeneous AADT ( pcu/day)
as obtained after application of recommended PCU conversion factors to the current heterogeneous
AADT (Vehicles/day)
Table 8: Computation of AADT in terms of Passenger Car Units (PCUs)
Vehicle Type AADT(Vehicles/day) PCU conversion factor AADT (PCUs/day)
Saloon Cars & Taxis 581 1.0 581
Light Goods, Pickups & 4WD 387 1.0 387
Small Bus 158 1.0 158
Medium Bus 4 2.0 8
Large Bus 24 2.0 48
Light Single unit Truck 92 2.5 231
Medium Single unit Truck 103 2.5 256
Heavy Trucks 39 3.5 138
Semi-Trailer &Trailer Trucks 144 3.5 504
Motorcycles 1501 1.0 1501
Total 3034 - 3813

Having completed the measurement of the current traffic on the existing Kasese – Mbarara highway for
use in the design of KIBP road network, the next step was traffic forecasting aimed at estimating design
traffic volume on which the design of geometrical features is to based, and design loading on which
pavement thickness design was to be based.

13
2.5.5 Estimation of Design Traffic Volume
The traffic volume expected at the end of the selected design life is called the Design Service Volume. I
determined the service volume for selection of an appropriate geometrical design for the KIBP road
network by projecting the current AADT determined in table 7 at appropriately selected traffic growth
factor(s) over the selected design life; the design life being the period during which the roads are
expected to carry traffic at a satisfactory level of service, without requiring major rehabilitation or repair
work.

I selected a design life of 15 years recommended for low traffic volume and paved. The Design Service
Volume expected at the end of 15 years was estimated by projecting the current AADT in table 8 using
appropriately selected traffic forecasting techniques as discussed in section 2.5.5.1.

2.5.5.1 Traffic Prediction to Estimate Design Volume.

Based on the MoWT (2010) projection technique for estimation of future design traffic volume, I
determined the design traffic volume in terms of PCUs/Day expected over the KIBP road network at the
design year (AADT15); AADT15 was used as the traffic input parameter for geometrical design.

AADT15 was to estimated by projecting the current traffic (AADT) to base year traffic (AADT1) first, and
then to future traffic (AADT15) at appropriately selected growth rates respectively, as determined from
the economic surveys and analysis carried out for the same project. AADT1 was estimated to be the
traffic flow expected at the end of the construction period of the roads or traffic expected at the start of
operation of the KIBP roads.

AADT1 was predicted from the current AADT0 in table 8 using equation (1); where, ‘i’ is the current
annual growth rate expressed as a decimal fraction, and ‘x’ is the anticipated number of years between
the traffic survey and the opening of the road.

AADT1 = AADT0 (1+i)x……………………………(1);

In context of KIBP design project, the operation of the roads was assumed to start at the end of 2015 as
informed by the client, which is the same year the detailed design for the roads has been carried out. By
subtitling for x=0 in the equation (1), the base year traffic was considered to be equal to the current
AADT0 calculated in table in vehicles/day and then then 8 in pcu/day.

The base year traffic also took cognisance of the possibility of diverted traffic and generated traffic
expected at the end of the construction of the roads or at the beginning of the operation phase for the
roads.
Therefore; it’s the base year AADT1 in consideration of the diverted and generated traffic that was
projected at appropriately selected respective growth rates for the different vehicle types to estimate the
design Service volume/capacity at the design year (15th year), all as explained in subsections 2.5.5.2
&3.

14
2.5.5.2 Diverted Traffic
Diverted traffic is defined as traffic that changes from one route or transport mode to the project road
after it has been improved without changing the origin and destination. According to the results of the
economic surveys and analysis carried out for the design project, there was no possibility of diverted
traffic hence not considered as part of the base AADT1.

2.5.5.3 Generated Traffic

Generated traffic can be defined as trips induced to use the new or improved facility as a result of time
and distance cost saving or because of new infrastructural developments. Generated traffic was
estimated in accordance with the recommendations from the economic analysis for the project. Table 10
indicates the recommendations adopted for estimation of the generated traffic for the design of the KIBP
roads; and table 11 shows the computation of generated traffic within the KIBP.

Table 9: Design Considerations adopted for estimation of generated Traffic

Recommendations Reference Design Consideration
 Conventional practice in developing  Section 4.25 of  0% of the normal AADT was estimated as the
countries often uses a factor of 20 to the Procedural generated traffic in case of light vehicles and
25% of normal traffic as the estimated Guide to buses;
level of generated traffic in the opening Economic Road  5% of the normal AADT was estimated as the
year of the scheme applicable to light Feasibility studies Generated Traffic, applicable for light, medium
vehicles only including cars, pick-up and by MoWT as and trucks.
four wheel drive, and minibuses.; quoted in the  The percentage of normal traffic adopted for
whereas a 5% to 10% of the normal economic estimation of the generated traffic were in
traffic is applicable for light, medium and analysis report. consideration of the planned land use for the
trailer trucks.  KIBP Master Plan park;
 The park was planned for factories and Report.  Normal AADT is equal to Baseline AADT in
industries in general terms. context of the KIBP design.

Table 10: Computation of generated traffic within the Industrial Park

Vehicle category Normal AADT1 % of AADT1 generated Generated Traffic
Saloon Cars & Taxis 581 0% 0
Light Goods, Vans & Pickups & 4WD 387 0% 0
Small Bus 158 0% 0
Medium Bus 4 0% 0
Large Bus 24 0% 0
Light Single unit Truck 92 5% 4.6
Medium Single unit Truck 103 5% 5.15
Heavy Trucks 39 5% 1.95
Semi-Trailer &Trailer Trucks 144 5% 7.2
Total 1532 19

2.5.5.4 Combined AADT1

The Annual Average Traffic expected at the beginning of operation of the KIBP roads in 2015 was
considered as a combination of normal traffic and generated traffic as shown in table12. It’s the
aggregated AADT in table 12 that was projected to the design AADT15. The Aggregated AADT was
projected at the respective selected growth rates summarized here in subsection 2.5.5.5

15
Table 11: Baseline AADT in Cognisance of Diverted traffic and Generated Traffic
Vehicle category Base Year AADT1 Diverted Traffic Generated Traffic Combined AADT
Saloon Cars & Taxis 581 0 0 581
Light Goods, Vans & Pickups & 4WD 387 0 0 387
Small Bus 158 0 0 158
Medium Bus 4 0 0 4
Large Bus 24 0 0 24
Light Single unit Truck 92 0 5 97
Medium Single unit Truck 103 0 5 108
Heavy Trucks 39 0 2 41
Semi-Trailer &Trailer Trucks 144 0 7 151
Total 1532 1551

2.5.5.5 Traffic growth.

The traffic growth rates were evaluated based on a number of factors including the income effect on
demand, population growth, the regional and national GDP and future development targets. From the
economic analysis, Traffic growth rates were appropriately established in respect of the three user
classes of cars (UC1), buses (UC2) and trucks (UC3) as shown in table 13.
Table 12: Traffic growth rates in percentages for the three user classes and growth periods
Forecast Average Growth Rate%
User Class
2014-2016
UC1 5.1
UC2 5.7
UC3 4.1

2.5.5.6 Design Volume/ Capacity (AADT15)

The design volume in terms of AADT15 was estimated using equation (1) all in accordance with the
MoWT (2010) Fixed Traffic Design approach projection techniques. The projected traffic was estimated
by appropriately substituting in the equation 1; for the traffic related design variables of combined
(AADT) calculated in table 12, Growth rates as adopted from the economic analysis and reproduce in
table 13, and the design life of 15 years appropriately selected as discussed in section 2.5.5.
Table 13: Estimations of AADT15 in PCUs/Day
Vehicle category PCUs 2015 Traffic growth rate (%) PCUs 2030
Saloon Cars & Taxis 581 0% 581
Light Goods, Vans & Pickups & 4WD 387 0% 387
Small Bus 158 0% 158
Medium Bus 8 0% 8
Large Bus 48 0% 48
Light Single unit Truck 231 5% 457
Medium Single unit Truck 256 5% 507
Heavy Trucks 138 5% 273
Semi-Trailer &Trailer Trucks 504 5% 998
Total (pcu/day) 2,311 3,417

16
The proposed road geometry was selected to adequately serve up to the traffic projected throughout the
selected design period. Therefore, as discussed in subsection 2.7.1 here after, the geometrical design
adopted for the KIBP roads alignment was selected in accordance with the MoWT design
recommendations for similar traffic volumes. i.e. 3417 pcu/day as cumulated in table 14.

2.5.6 Estimation of Design Traffic Loading

For pavement design, only the vehicles that carry significantly heavy loads were considered important in
the determination of design traffic loading. The pavement design was governed by the number of
repetitions of a standard axle. i.e 80KN single axle load. The sum of equivalent repetitions of a standard
axle obtained for all commercial vehicle load classes anticipated during the design life was used as the
design input parameter derived through the following steps.

 Determination of the current AADT flow for only commercial vehicles (i.e. all vehicles with
overladen weight greater than 4000Kg).
 Prediction of Future traffic Volume
 Selection of applicable Equivalent Damage factors
 Determination of ESA for the respective numbers in the vehicle classes;
 Cumulating of the ESAL to determine the design ESAL

The current AADT prevailing in the year of the Traffic counting was already estimated as discussed in
subsection 2.5.3 before. The expected commercial traffic volume expected to use the roads was
estimated from the current AADT by use of recommended projection techniques and selected traffic
growth from the economic analysis carried out for design project.

I determined the design input value for the anticipated loading in such a way that the resulting pavement
alternatives proposed for KIBP road network alignment will carry traffic loads over the selected design
life of 15years in a satisfactory manner without significant structural failures for the road to require
rehabilitation before expiry of the design life.
2.5.6.1 Traffic Prediction
The number of commercial vehicles expected to use the KIBP roads during the design life was
adequately estimated from the prevailing traffic volumes in the year of traffic counting using equation 2
from the typical approach followed by MoWT (2010) for traffic loading prediction.
𝒓 𝒑
⌈𝟏+ ⌉ −𝟏
𝑫𝑻 = 𝟎. 𝟓 ∗ 𝑻 ∗ 𝟑𝟔𝟓 ∗ 𝟏𝟎𝟎
…………………………….. (2)
𝒓⁄𝟏𝟎𝟎

Where:
DT is the cumulative design traffic in a commercial vehicle category (one direction);
T = Annual average daily traffic in a commercial vehicle category in the first year (both directions). I.e.
average daily traffic flow for the first year (not the value at opening to traffic, but the projected average
for the year)
r = average assumed growth rate, per cent per annum as determined in subsection 2.5.5.5; and
p = design period in years which was selected as 15 years in subsection 2.5.5
0.5 is a factor to allow for lateral distribution of traffic loading as recommended by MoWT (2010) for the
single carriage way at least 6.0m wide.

17
The Annual Average Traffic that was projected to determine the future traffic volume DT took
cognisance of the potential of diverted traffic and generated traffic as determined in section 2.5.5.2 and
2.5.5.3.The results of calculations for the DT are indicated in table 15.

Table 14: Estimation of Future Commercial Vehicles (DT)

Vehicle category Normal Diverted Generated Combined Growth DT
AADT Traffic Traffic AADT Factor
Light Goods, Vans & Pickups & 4WD 387 0 0 387 1 70,628
Small Bus 158 0 0 158 1 28,835
Medium Bus 4 0 0 4 1 730
Large Bus 24 0 0 24 1 4,380
Light Single unit Truck 92 0 5 97 21.6 382,374
Medium Single unit Truck 103 0 5 108 21.6 425,736
Heavy Trucks 39 0 2 41 21.6 161,622
Semi-Trailer &Trailer Trucks 144 0 7 151 21.6 595,242

Generally, to estimate the total projected repetitions of the commercial traffic loading in terms repititions
of standard load unit (Standard Axle Load = 8160kg) for which pavements should be designed., it is
necessary to have an estimate of the axle load spectrum defined as the number of passess for a
different groups of axles. Thereafter, Equivalent Standard Axle Load Factors (ESAL) defined the Load
Equivalency Factors in ESAs, are determined using the formular below and then used to convert the
different axle load groups into equivalent repititions of a standard axle.
The formula used for converting real axle loads which may not be standard to Equivalent Standard
Axles (ESAs) is:
𝐸𝑆𝐴𝐿 𝑓𝑎𝑐𝑡𝑜𝑟 = (𝐴𝑥𝑙𝑒 𝐿𝑜𝑎𝑑 𝑖𝑛 𝐾𝑔|8160)𝑛
Where:
ESAL is the load equivalency factor in ESAs, and n is the relative damage exponent as influenced by
various factors, with the most significant being the pavement configuration. Table 2.2 from MoWT(2010)
indicates recommended n values to be used for the pavements within the context of MoWT Design
guide, and Table 2.3 of the same design guidelines gives load equivalency factors for different axle
loads and n values derived from the Equation above.

In order to convert traffic volume(Commercial vehicle from the traffic count) into Equivalent Number of
stadard axles, Vehicle Damage Factors are determined from converting surveyed axle loads to
ESAs/vehicle classification, and then deriving a representative average value.

2.5.6.2 Selection of Appropriate Damage Factors.

The axle load spectrum was obtained from the conducted axle load surveys where measurements of
axle loads of a sample commercial vehicles plying on the Kasese – Mbarara road facility were carried
out for 3 days at the same station used for traffic counts. However, the axle load survey data was not
utilized due to inconsistencies with the historical traffic, and in accordance with the recommendations of
UNRA. The UNRA local station engineer in the project area informed that the axle load surveys were
inaccurate from his experience with the drivers in the area. He informed that sample weighed was not
representative enough since drivers in the region tend to suspend their loading trips when they know of
weigh bridge operation at the station until when such operations are complete. He added that, reliable
axle load spectrum information can only be got from axle load surveys that last for at least 7days, when
the truck drivers cannot delay the trips any longer.

18
Therefore, I adopted for design, the VDF that have been successful used by other consultants to design
for various project roads in 2009 and 2010 in the country. Such factors were assumed valid on the
assumptions that; axle load distributions remain unchanged for year to year for longer periods unless
with introduction of vehicles and changes in their regulations and enforcement; pavement thickness
design is relatively insensitive to the potential difference in the cumulative ESAs; and that all the roads
considered for selection of the factors serve the same function and are of the same type; all as
contended by TRL(1993).Table 16 indicates the selected VDF used for design of KIBP

Table 15: Mean Vehicle Equivalency factors for each vehicle class as adopted from design reports by other
Consultants
Source Mean Equivalency factors
Car 4WD S.B MB L.B S.T M.T H .T T.T Remarks
Adopted for the
0 0.01 0.35 0.6 0.75 .35 0.52 4.21 8
design
Source: Engineering Design reports for Mukono-Katosi, Nyakahita–Fort portal Road Project, Busega – Mityana Road
Project, 2009

2.5.6.3 Conversion of Traffic flows to cumulative total ESAs in each direction

In order to convert traffic volume(Commercial vehicle from the traffic count) into Equivalent Number of
reptitions of a stardard axle, The average VDF factors in table 16 were used. For each of the vehicle
class, the appropriete VDF was multiplied with the number of vehicles expected to use the roads within
the design period as already determined in table 15.Table 17 indicates results of the ESAL expected
from each of the vehicle class throughout the design period

Table 16: Computation of ESAL

Vehicle category DT VDF ESAs
Saloon Cars & Taxis 106,033 - -
Light Goods, Vans & Pickups & 4WD 70,628 0.01 706

Small Bus 28,835 0.35 10,092

Medium Bus 730 0.60 438
Large Bus 4,380 0.75 3,285
Light Single unit Truck 382,374 0.35 133,831
Medium Single unit Truck 425,736 0.52 221,383
Heavy Trucks 161,622 4.21 680,429
Semi-Trailer &Trailer Trucks 595,242 8.00 4,761,936
Total ESAL 5,812,100

2.5.6.4 Determination Total ESAs

The design was based on the total number of applications of standard axle loading during the design
period of 15 years. Therefore the cumulative ESAs were determined as 5,812,100. Table 17 indicates
the calculations for the Total ESAs using the expression below:
CESAL = ∑𝒎
𝒊 𝒇𝒊 𝒏𝒊

19
Where m = number of vehicle classes; fi is the VDF for the ith vehicle class, ni is the number of
applications of the ith vehicle class during the design period

2.5.6.5 Selection of Design Traffic Loading Class

Different design guidelines have suggested pavement structures classified in various traffic categories
by cumulative ESAs expected. For instance, MoWT(2010) design guide gives such classifications in
Table 2.5 as reproduced in table 18.Similary, TRL (1993) recommends for the same classes within the
traffic ranges in million ESAs

Table 17: Traffic Classes

Traffic Class Designation

T1 T2 T3 T4 T5 T6 T7 T8
Traffic ranges
(million ESAs)
< 0.3 0.3-07 0.7-1.5 1.5-3 3-6 6-10 10-17 17-30

The design traffic loading determined (Cumulative ESAs = 5,812,100) was used to decide which traffic
class category was applicable. Accordingly, T5 was selected as the Traffic Class

20
 2.6 CONSTRUCTION MATERIALS INVESTIGATIONS.
The third factor which influenced pavement thickness was the choice of road construction materials for
the construction of the pavement layers. Material investigations were carried out as an integral part of
design of KIPB road network (MoWT, 2010; TRL, 1993). The results of such investigations formed the
basis for identification of sources of locally available road construction materials and recommendations
on the necessity for imported materials required to carry out engineering design of the KIBP roads. I
successfully executed the following leading roles during the materials investigation and testing activity:
 Identified material types and suitability for use in pavement layers;
 Located sources of the materials within and outside the project area;
 Selected the required material properties for evaluation of materials,
 Supervised the sampling of materials for laboratory testing,
 Analyzed material test results for suitability of material properties as design parameters;
 Recommended on the use of materials in the different pavement layers;
2.6.1 Material Type and Suitability.
According to the ToRs for the works contract between KKATT and UIA, The later was required to
determine the choice and properties of the available pavement design and construction materials in
consideration of local good practice as pre-requisite for the selection of such material.

In context, I identified the following different materials available for use in the design of different
pavement layers. The same material types had been successful utilized in the construction of the
previous road projects within the project area.
 Gravel and aggregates could be used in the base and the sub base,
 Lime which could be used in the base or sub base layer especially for stabilization purposes;
 Bitumen which could be used as Prime coat and tack coat bitumen in asphalt bases and/or
surfacing materials and surface dressings.
Most of the material like gravel has been previously located within the project area, and others like
bitumen were previously transported from outside the project area.
2.6.2 Material Sources.
I located the identified materials’ sources within the project area for all the materials except for bitumen.
All the sources were identified within the most economical haulage distance and in sufficient quantity
and quality as detailed in table 18. I located the potential materials’ sources through Field Material
Surveys; Consultations with the Kasese UNRA Station Engineer and Kasese Local Government
Engineer; And by looking out for clues to existence of previous exploitation of material sources in the
project area such as quarries and borrow pits. Photographs in figure 6 indicate progress for the material
sampling activity.
Table 18: Material Sources identified within and outside the project.
Material Potential source Recommendation Remarks
Gravel. Kirembe BP Located at about  These were all existing BPs that had been previously used in the
2.5Km from the KIBP. road construction projects in Kasese.
Kogere BP.  These were found in the most economical haulage distance to
Kikorongo BP located at minimize haulage costs.
approximately 19.6km from the  I had successfully experienced use of gravel from Kikorongo Bp
KIBP. during periodic maintenance works on Katunguru - Ishasha road
in the position of Assistant Resident Engineer (ARE).

21
 Aggregate Kyampetsi quarry in Bushenyi  I found no existing quarry in the Kasese area.
s. district.  It’s was not feasible to set up a stone quarry for construction of
7km for KIBP road network.
 Aggregates used on-going road construction works are obtained
from Kyampetsi Quarry; For example, for the upgrading of the
Ishaka – Kagamba road by DOTT Services Ltd.
Lime. Muhokya Lime Works in Kasese  The lime has been successfully used in the road construction
located at 1 km from the Project projects in Kasese.
Area.
Sand. River Nyamabwa in Katunguru  The sand can be been satisfactorily used in construction of culvert
end structures on the previous road construction projects in the
Kasese.
Bitumen Kampala  Bitumen can be bought from reliable sources in Kampala like Shell
Uganda Limited.

Borrow Pit Sampling in Kogere Borrow Pit in Kirembe

Existing borrow pit at Kikorongo in use.

Figure 6: Progress photographs for the soil and materials investigations activities.

22
2.6.3 Material Properties and Suitability for use in the pavement layers.
In addition to economical haulage distance and sufficient quantity, pavement materials should be
located in sufficient quality for pavement design, to avoid escalation of costs and unnecessary
expensive delays whilst new sources are being investigated or the roads redesigned to take account of
the actual materials especially when material quantity and quality deficits are realized during the
construction stage (TRL, 2005). Accordingly, the pavement materials identified were evaluated through
sampling and laboratory testing of the representative material samples. Based on the materials test
results extracted from the Materials Report submitted by KCML, I characterized the identified materials
for the following purposes:
 Classification/grading of pavement materials;
 Determined the appropriate materials’ properties as design inputs with the frame work of the
design method selected i.e. MoWT (2010) design Method;
 Appropriately selected design input values for material types parameters that impact the
performance of the pavement structure.

However, prior to characterizing the pavement materials, I reviewed to ensure that appropriate testing
conditions were selected by the testing laboratory (KCML). As recommended by MoWT (2010) and TRL
(1993), the testing conditions were representative of the anticipated field conditions to which the
materials will be subjected to during the service life.
Thereafter, I analyzed suitability of the respective materials’ properties and design parameters for
compliance to the given relevant material specifications in adherence to the pavement design
requirements for parameters selected within the MoWT design frame work. Accordingly, I made the
conclusions and recommendations for the respective pavement layers and construction pavement
materials as indicated in table 20.

Table 19: Materials Recommendations on suitability for Pavement layers

Layers Source Recommendation Reference as per MoW&T
General Specifications
Fill BP at Kogere & BP at G15 Table 3602/1
Kirembe CBR; Min. 15
Max PI: 25
Max Particle Size: 0.5 of
compacted layer.
Subbase Layers BP at Kikorongo. G30; Free Table 3702/5
Haulage distance CBR: 30
to be specified as Max LL: 45
20km. Max PI: 16
Max LS: 8
Min GM; 1.2
Base Layer BP at Kikorongo with Cemented Layer Table 3802/2;
4% stabilisation Material Class of C1.5; CBR .>
80 after 4% Lime stabilization
Aggregates for Surface Quarry at Kyampetsi. DBST – (14/20) Table 4502/1 & 4502/2;
Dressing and / or Asphalt However, and (10/14) Grading & Mechanical
works recommended that Requirements
the Contractor seeks
own source.

23
Layers Source Recommendation Reference as per MoW&T
General Specifications
Other Construction Materials
Lime Muhokya Lime 4% lime Uganda Standards US 288-
Factory in Kasese 2001 & AASHTO m216-92
(1996)
Water River Nyamambwa in BS 3.48
Kasese
Sand Katunguru area BSEN 1367-4;2002.
Cutback Bitumen, MC-30 Contractor to source All properties to adhere to
AASHTO Designation M82-75
(1996).

24
 2.7 GEOMETRIC DESIGN
Geometrical design is concerned with satisfactory functional performance which is defined as the ability
of the road to provide a comfortable, economical and safe ride to the road user. Functional performance
is mostly dependent on the surface characteristics of the road including variation in the longitudinal
profile and transverse profile (MoWT, 2010; TRL, 2005).

Therefore, in establishing the geometrical design for KIBP roads’ alignment, I was concerned with the
geometrical elements of the road which include Cross section elements, Sight distance considerations,
Horizontal alignment details, Vertical alignment details and Intersection control.

While designing such geometrical elements, I considered the following influencing factors: Road
classification, Terrain classification, Design speed, Highway Capacity including traffic volume and
characteristics, Design Vehicle and vehicle characteristics, and Highway economics which vary from
one road to another based on the function.

In order to achieve the geometrical design objectives, I adopted the standard design control and criteria
for the recommended geometrical design factors suggested by MoWT (2010) as explained in the
following sections.
2.7.1 Functional Classification.
Overall, it’s not economical to have same design standards for all the different types of roads because of
the variation of influencing factors like; Traffic volume and type (Not all roads carry the same amount
and type of traffic; purpose of the road (some roads provide access and others provide high speed
movement); and importance/priority of the road hence the justification for classification of the roads into
various classes based on the function.

When choosing geometric design standards for a particular situation it is necessary to consider the
purpose for which the road is being provided. The major function of the roads in KIBP was to provide
access. MoWT (2010) specifies six design classes of roads of which class I, II & III are bitumen
surfaced; and class A, B & C are Gravel surfaced roads. The division into Road Design Class is
governed by the design speed and design traffic. The road capacity, defined as the Passenger Car Unit
(PCU) volume per day is the primary determinant of road design class.

Accordingly, I adopted Design Class II Paved corresponding to estimated design traffic of 3417 PCUs
as determined in section 2.5.5.6 all in accordance with the recommendations of MoWT (2010),
Geometrical design manuals, table 4-2a. Table 20 indicates the design standard adopted for the road.

Table 20: Road Design Classes adopted from Table 4-2a of MoWT Geometric Design Manual, 2010
Capacity Maximum Design speed Functional
Design Road-way Kph Classification
[pcu x
Class width[m]
1,000/day] Level Rolling Mountainous A B C D E
II Paved 4–8 10.0 90 70 60 √ √ √

25
2.7.2 Design Speed.
Design speed may be defined as the maximum safe speed that can be maintained over a given section
of the road where conditions are so favorable that the design features of the road govern (MoWT, 2010).
Design speed primary depends on the terrain and class of the road. According MoWT design standards
for Urban/Peri-urban roads, the design speed was modified to 50kph along sections of KIBP road
network. At the design speed, the vehicles are anticipated to maneuver safely and comfortably on the
KIBP roads.
2.7.3 Design Vehicle.
For purposes of geometric design of KIBP road network, I selected a design vehicle with larger physical
dimension and a larger minimum turning radius than most vehicles in the traffic stream. Therefore an
Interstate Semitrailer (DV-5) was selected with larger dimensions and highest minimum turning radius.
I selected the physical dimensions of the design vehicle as per MoWT suggestions for the Interstate
Semitrailer (DV-5) indicated in table 5 – 10. The table 21 indicates the selected values for the design
vehicle characteristics.

Table 21: Physical Dimensions adopted for the Design Vehicle.

Design Symbol Overall (m) Overhang Minimum Minimum

Wheel base
Vehicle (m) design inside radius

(m)
turning (m)
Length
Height

width

Front

Rear

radius (m)

Interstate DV-5 4.1 2.6 21.0 1.2 0.9 6.1 & 12.8 13.7 2.9
Semitrailer
Source: Table 5-1 of MoWT Geometric Design Manual, 2010

2.7.4 Cross sectional Elements.

The most import factors to be considered for geometrical design purposes are; width of carriageway
(running surface) and width of shoulder, cross fall (camber), and width of road reserve. Accordingly,
having established the design standard for the KIBP road network as Design Class II Paved, I adopted
the appropriate design values for the cross section elements following the MoWT design guidelines for
the same. The design values and their validity to the recommended standard values are indicated in
table 22 for each of the cross section element.

Table 22:Design Physical Dimensions for KIBP Roads Cross Section.

Design Design Standard Definitions, Design Recommendations and observations.
Parameter Dimension Values from
MoWT (Table
6-10).
Road 20.0m 50m  Road reserve is the amount of land available for road
reserve construction.
width  The total width of the road reserve may be from 10m to
more than 50m depending on the availability of land.
 In consideration of existing rights of way and developments
for the park, I recommended a width of 20m as adequate for
the roads, respective drainage facilities, services, future
road improvement activities, provision of fill for road

26
 Design Design Standard Definitions, Design Recommendations and observations.
Parameter Dimension Values from
MoWT (Table
6-10).
construction and to control erosion.
Carriagewa (2X3.5m)= 6.0  Carriageway is the portion of the road used for the
y width 7.0m movement of the vehicles exclusive of shoulders;
 7.0m width was recommended for the KIBP road network
given the design vehicle as a commercial one;
 Such width allows for a sufficient clearance.
Roadway 10.0m 10.0m  Roadway for single carriageway is the portion of the road,
width consisting of the shoulders, and the carriageways.
 The Width adopted is consistent with the standard values
hence adequate for the estimated design traffic.
Shoulder 2X1.5m 2X2.0m.  The shoulder is the portion of the roadway between the
width outer edge of the travelled lane and the inside edge of the
ditch, gutter, curb, slope or median (in divided roadways).
 The reduced width further controlled property interference
and at the same time allows for space for vehicle repairs in
case of break downs; Provide lateral support for pavement
sub base, base and surface courses.
Carriagewa 2.5% 2.5%  Cross fall is needed on all roads in order to assist the
y cross fall shedding of water into the side drains.
 The same value was adopted for the design class surface
characteristics as recommended by MoWT (2010).
 The network roads have been designed with a crown
section except at horizontal curves where super elevation
has been provided.
Should 4% 4%  The slope is adequate for effective drainage of travelled
Cross fall. way.

2.7.5 Horizontal Alignment Details

Straight roads are not desirable from the safety point of view and for practical reason hence the
necessity for provision of tangents and horizontal curves. Where the straight alignment had to be
changed, the five major elements that were adequately considered for geometrical design are;
Horizontal curves, Super elevation, Transition curves, Extra – Widening, and Set back distance (MoWT,
2010). I selected the related physical dimensions for such elements in accordance with the
recommended technical requirements for the same by MoWT (2010).The key design criteria for the
horizontal alignment was the minimum radius of curvature, the minimum stopping sight distance and the
minimum passing sight distance.

The basis for the geometrical design of each of the elements considered is summarized as indicated in
the table 23. In the same table, I have explained the relevant design parameters including
recommendations on the design criteria that were used in the design.

27
Table 23: Design Standard and Recommendations considered for Horizontal alignment design
Geometrical Definitions and Basis for design Design Remarks on Design Criteria
design Parameter
element s/Consider
ations.
Horizontal  Circular curves connecting The Rmin selected for design allowed for adequate
Curves. between straight sections. minimum sight distance
 Necessary to fluently connect radius of
between tangents. curvature
(Rmin),
Super  Super elevation is defined as the  Design  For a given design speed, MoWT
elevation. benching of the roads on the inside Speed; recommends for Maximum super elevation
of the horizontal curves to  Terrain; and minimum super elevation according to
counteract the centrifugal force and  Climate, the terrain conditions.
hence ensuring the safety and  And  Accordingly, I adopted for design super
comfort of road users by reducing Type of elevation, the recommended values for flat
the overturning and skidding effect the Area. and rolling terrain respectively.
of the centrifugal force.  Therefore, given the lower design speed due
 MoWT recommends for the basic to planned marginalized park development,
super elevation Design Equation design super elevation was limited between 4
as: e+f = V2/127Rmin where, e is – 6% hence the single value of 5% used for
the super elevation, V is the design design for all curves to facilitate safe
Speed, and Rmin operations.
Set back  Set back distance is defined as the SSD and Setback distance is affected by horizontal
Distance clear distance in the inner side of hence curves radius and length of the horizontal
the horizontals which must be Visibility. curves.
available to make sure the
adequate sight distance is available
on horizontal curves.
 Obstructions to the sight distances
that could be caused by buildings
and trees should be avoided by
specifying the required setback
distance for adequate SSD.

According to the design parameters and design recommendations, MoWT has recommended for the
appropriate design criteria for the relevant horizontal alignment geometrical features which values I
adopted for the design of the KIBP horizontal alignment elements as indicated in table 24.

Table 24: Design Criteria for Horizontal Alignment

Item Design Rmin Design Min. Design Super Design Transition Design Set back Design
Element Criteria SSD Criteria elevation Criteria curve Criteria Distance Criteri
Length a
MOWT Standard <100 < 58 4-6%
1.0 Horizont 100 60 pass 5 pass 34
al
Curves

2.7.6 Vertical Alignment Details

The vertical alignment of a road has a strong influence upon the construction cost, the operating cost of
vehicles using the road, and the number of accidents hence justification for geometrical design of roads
for vertical alignment. The two major aspects of vertical alignment for design of the KIBP roads were

28
Vertical Curvature, which is governed by sight distance and comfort criteria and the Gradient which is
related to vehicle performance and level of service.

In context of the Design Criteria for the vertical alignment design elements, I adequately designed the
vertical curves for the KIBP road network to provide adequate sight distances over crests and sags
without presenting any sudden hidden changes in alignment to the drivers. In addition, the Gradients
were considered from the standpoint of both length and steepness, and the speed at which heavy
vehicles are assumed to enter the respective gradients. Influencing factors like speed, sight distance,
and acceleration/deceleration were observed as design considerations that potentially influenced the
vertical curvature and grade as explained in table 25 for each of the element/parameter. Furthermore,
the designed vertical alignment was also influenced by the flat and rolling terrain classification of the
project area

Table 25: Design Standard and Recommendations considered for Vertical alignment design
Vertical Definitions and Basis Design Remarks on Design Criteria
Alignment for design Parameter
Geometrical s/Consider
design element ations.
Grade  According to the  Maximu  The effect of grade on speed is more pronounced in case
Elevations. results of the m grade of trucks than Passenger cars;
topographical of slope;  Maximum speed that can be maintained by the trucks
surveys, the natural  Minimum depends on the length and steepness of the grade and the
ground of the project Grade of trucks weight/power ratio;
area for the KIBP slope;  MoWT has suggested control grades depending on terrain
roads had slopes  Critical for a particular design speeds;
and undulations of Length of  Minimum Longitudinal grade facilitates surface drainage
various magnitudes grade, characteristic depending on the pavement type,
and hence the  speed  Maximum length of designated upgrade on which a loaded
justification for truck can operate without an unreasonable reduction in
vertical alignment speed is Critical Length.
design to provide a
smooth profile
consistent with the
Flat in some areas
and Rolling in others
terrain as classified
in the sections
before of the same
report.
Vertical Curves  Vertical curves were  Sight  MoWT (2010) recommends for sight distance
provided to effect Distance considerations and minimum length of curve as the major
smooth transitions consider considerations for design of vertical curves.
between ations;  Sight distance is the distance ahead that can be seen by
consecutive straight  Minimum the driver.
gradients in the road Length of  The sight distance needed for safe stopping from travelling
network. curves. speed is the ‘stopping sight distance’ and the sight distance
needed to see ahead for safe overtaking is known as the
 Vertical curves ‘passing sight distance’. Stopping sight distance (SSD) and
should be simple in Passing sight distance (PSD) are the aspects of sight
application and the distance that I considered for the design of crest curve for
resulting design for KIBP network.
such curves should  Sight distance considerations in terms of headlight sight
be safe and distance governed the design of sag curves and the same

29
 Vertical Definitions and Basis Design Remarks on Design Criteria
Alignment for design Parameter
Geometrical s/Consider
design element ations.
comfortable in criterion governed the design of sag curves for the KIBP
operation, pleasing road network.
in appearance, and  The headlight sight distance aspect was used to determine
adequate for the length of sag curves for the roads.
drainage.

In accordance with the design parameters and considerations discussed in table 26 for vertical
alignment, MoWT (2010) has recommended minimum values for the respective design criteria; these
were adopted in the vertical alignment design for KIBP. In addition, MoWT suggested Kmin values
(Measure of curvature) that are useful in determining Minimum length of vertical curves to provide the
minimum SSD for each of the various design speeds. K is the reciprocal L/A defined as the horizontal
distance needed to make 1% change in gradient.

Similarly, I designed the vertical alignment to conform to and or better the MoWT recommended design
criteria for the geometrical design parameters for type II paved roads as indicated in table 27.

Table 26: Design Criteria adopted for vertical alignment design of KIBP roads alignment
Item Design Crest Design Sag Curve Design Designated Control Maximu Design
Elemen curve SSD Criteria for SSD in Criteria Grade Grade m grade Criteia
t K value Kmin terms of for Kmin
adopted. Head light
Sight
distance.
Design Speed 9 9 11 11 5 4 – 6% <11%
of 50Kph for
Urban/Peri-
Urban

In general, the geometrical characteristics of the existing road network alignment were obtained from
ground data generated during the topographical surveys. This data was then imported into AutoCAD
Civil3D software with an Advanced Road (ARD) extension to generate a digital ground model of the
routes’ corridors. Therefore, I used an interactive procedure between engineering and computer
software to produce a geometrical record of the plan and profile of the existing route corridors as
established during the master planning exercise, both for the assessment and creation of a model to act
as the basis for the alignment designs.

The general approach to the horizontal and vertical alignment was to use the corridor of the pre-
established road network as much as possible in consideration of the intended commercial function of
the KIBP.

However, the vertical alignment in some sections was raised to an average of 0.5m above the existing
profile within limits of the maximum grade. This was done to raise the low laying existing profile, improve
the drainage of storm water across and along the alignments.

30
2.7.7 Engineering Safety Measures
Road safety should be a primary consideration in the design of any road. Similarly, during the
geometrical design of the KIBP road network, I adopted the appropriate highway design standards for
accident prevention through increased carriageway width, correct road gradient and curvature to less
the risk of collision, appropriate surfacing.

In addition, I allowed for; Appropriate Road markings and Delineations, Road signs, and street lighting
all as the MoWT (2010) and MoW&T (2004) recommendations for the same.
2.7.8 Design Drawings
From the DTM produced from the Topographical surveys, AutoCAD Civil 3D was used to generate the
design drawings and profiles in all dimensions. The design drawings are attached in appendix 2F of the
report.

31
 2.8 PAVEMENT DESIGN
A Pavement is a structure that carries vehicular loading (MoWT, 2010). The purpose of structural design
was to limit the stresses induced in the subgrade by traffic to a safe level at which subgrade deformation
is insignificant whilst at the same time ensuring that the road pavement layers themselves do not
deteriorate to any serious extent within the specified design period of 15 years. In context of pavement
design for KIBP road network, I selected appropriate values to the design parameters that influence the
structural performance of the resulting pavement within the design period, all as discussed in the
following subsections of 2.8.
2.8.1 Design Variable/Parameters
I took into consideration the influence of the following external parameters which are external to the
pavement.
 Subgrade (type, Classification, and strength).
 Traffic (Baseline flow, forecast and CESAL);
 Construction Materials and geotechnical information (field survey and material properties);
 Climatic conditions (Predominantly wet conditions) determined during the hydrological surveys
and analysis for the project.

Consequently, I appropriately selected output design values to the internal pavement design parameters
of layer material and thickness as influenced by the external design variables; all in accordance with the
recommendations of UNRA design Manual and ORN31 design guidelines as discussed respectively in
the following sub sections.

2.8.2 Design Process.

Generally, the design procedure adopted was in line with the requirements of MoWT (2010) Design
Frame work guide and the ORN31 Design Frame work as summarized:
 Estimation of the cumulative traffic loading expected during the design life;
 Defined the subgrade strength over which the KIBP road network will be built;
 Defined the nominal operating climate;
 Determined any practical aspects which influenced the design selection; and
 Selection possible pavement structure alternatives;
 Determined the structural number for the pavement alternatives.

Each of the activity is discussed respectively for each of the design procedures including explanation of
how each of the design variables was appropriately considered in the determination of the design
alternative.

2.8.3 Pavement Alternative Based MoWT (2010) Guidelines

Design values to the external design variables were appropriately selected in such a way that the
resulting pavement alternative should perform in a satisfactory manner both functionally and structurally,
with the design life of 15 years. The design variables provided the basis for selection of pavement
structure alternative as discussed here after for each of the variable considered.

32
2.8.3.1 Traffic Loading Class
MoWT (2010) design guidelines have suggested pavement structures classified in various traffic
categories by cumulative ESAs expected. With the CESAL determined in section 2.5.6.4, T5 was
appropriately selected accordingly. Table 28 indicates the results of the adopted traffic class.
Table 27: Traffic Class Adopted for all the project roads
Road Name Design Period (years) CESAL Traffic class adopted for pavement design
KIBP Roads 15 5,812,100 T5

2.8.3.2 Subgrade Strength design Class.

In addition to the design traffic class, design CBR appropriately determined in subsection 2.4.5 for the
alignment subgrade soils was satisfactorily considered as the other major input in the design of
pavement alternative for KIBP. MoWT (2010) classified the subgrade strength design value expressed
in terms of design CBR value corresponding to the most critical moisture. Accordingly, I appropriately
selected S4 as the design subgrade class corresponding to the 4 days soaked design CBR determined
before in subsection 2.4.5, all in accordance with the MoWT (2010) recommendations for the same.

2.8.3.3 Nominal Operating Conditions

In addition to selection of design traffic class and design subgrade strength class, expected nominal
operation conditions as influenced by moisture variations was defined to allow use of the design
catalogues for selection of appropriate pavement design alternatives. I assumed predominantly wet
climatic conditions in accordance with the recommendations from the hydrological surveys and analysis
carried out for the same project.

The design subgrade strength class, design traffic class, and the assumed moisture conditions were
entered in the catalogue of structures forming part of the MoWT (2010) design guide to select the
pavement design structure alternatives as discussed in 2.8.3.4 and in table29.

2.8.3.4 Selection of Pavement Structure alternative.

With the T5, S4, and predominantly wet conductions; the resulting pavement structure alternatives were
appropriately selected from Chart W1 for Granular base/granular sub base in wet regions. Accordingly, I
selected granular base/granular sub base with surface dressing or hot mix asphalt as the potential
alternatives pending evaluation to decide on the most economical alternative. The respective layer
thickness as recommended in the chart are indicated for the pavement structure alternative are
indicated in table 29.

Table 28: Pavement Alternative (MoWT, 2010)

Traffic Subgrade Class Norminal Operating Pavement Structure alternative base on MoWT,
Class adopted Conditions Pavement Design Manual Catalogue of structures (Chart
W1)
T5 S4 Predominantly Wet 50 mm Asphalt Concrete
conditions 200mm Granular Base
175mm Granular Sub base

33
2.8.3.5 Availability of constructional materials
The results of the constructional material investigations and tests indicated availability of constructional
materials in sufficient quantity and quality for construction of such selected pavement type. The granular
materials especially gravel was located within an economical distance of up to 20km
2.8.3.6 Pavement Structure Number.
The final design equation for flexible pavements according to AASHTO Flexible Pavement Design guide
is as follows (Huang, 1993):
𝐥𝐨𝐠[∆𝑷𝑺𝑰⁄(𝟒. 𝟐 − 𝟏. 𝟓)]
𝐥𝐨𝐠 𝑾𝟏𝟖 = 𝒁𝑹 𝑺𝟎 + 𝟗. 𝟑𝟔 𝐥𝐨𝐠(𝑺𝑵 + 𝟏) − 𝟎. 𝟐 + + 𝟐. 𝟑𝟐 𝐥𝐨𝐠 𝑴𝑹 − 𝟖. 𝟎𝟕
𝟎. 𝟒 + 𝟏𝟎𝟗𝟒⁄(𝑺𝑵 + 𝟏)𝟓.𝟏𝟗

Where:
W18 is the Traffic – million ESALs; ZR is the normal deviate for a given reliability R; So is the standard
deviate (0.45 for flexible pavements), Serviceability loss (∆PSI); Mr is the Effective Roadbed resilient
modulus (ksi); SN is the required structure number over the given subgrade strength value.
Therefore for design CBR of 8 (10% of sample to have alower CBR value from the cumulative S curve
for the values in subsection 2.4.5), I determined the Required Design SN according AAHTO design
method through the following steps. Thereafter, I calculated the structure number for the pavement
structure as a result of MoWT (2010) to ass adequacy.
 Selected the Initial Serviceability index at 4.5 (Based on road condition immediately
construction)
 Determined the desired terminal serviceability pt = 2.0 in accordance with the recommendations
for the same class (Lower class highway for access in a rural area);
 Determined the Serviceability loss , ∆PSI = (pi-pt) = 2.5
 Determined the total ESAL =. 5,812,100 Million discussed in subsection 2.5.6.4
 Selected the reliability R =80% as recommended for the selected structural design period of 15
years;
 For R = 80%, I selected the corresponding normal deviate ZR = -0.841 from Table 11:15
(Huang,1993), and the standard deviation at S0=0.45 (0.4 to 0.5 range recommended for
flexible pavements, I considered the Midpoint of the range)
 Taking the design CBR at 8%, I determined MR= 12,000psi from the Equation:
𝑴𝑹 = 𝟏𝟓𝟎𝟎𝐂𝐁𝐑; A according Henkelom & Klomp as referenced in Huang (1993), the equation
provides accurate values of MR for CBR values of less than 20, and that the correlation appeared more
reasonable for fine grained soils and sands rather than granular materials hence its justification for use in
pavement design for KIBP.
 As shown by the arrows in figure 11.25 attached in appendix 2D, starting from R= 80%, I drew
a series of lines through So= 0.45, ESAL or W18 = 5,812,100 Million ESA, MR= 12,000psi, and
∆PSI = 2.5 and intersect SN at 3.3.
Therefore, a pavement of SN = 3.3 would be adequate for the KIBP roads at 80% reliability that such a
pavement can satisfactorily perform within the design period, accommodating up to such repetitions of
standard traffic loading. The structure number (SN) for the designed pavement structure alternative was
calculated for comparison against the required Design SN = 3.3.

The SN for the pavement alternative was estimated from equation (3) suggested by AASHTO. The
equation used account for the variations of local conditions from the AASHO test conditions specially the

34
drainage conditions and subgrade. The SN determined for the structure indicates the strength of actual
designed pavement structure alternative.

SN = a1D1 + a2D2m2 + a3D3m3………………………. (3)

Where;
a1, a2 and a3 are the layer coefficients based on material properties for the Wearing course, sub base,
and base for the pavement structure on a subgrade represented by the parameter MR. For each of the
layer material, the layer coefficient is a measure of the relative ability of a unit thickness of such a
material to function as a structural component in the pavement structure. The layer coefficients for
respective different layer material were estimated from the estimation charts attached in appendix 2D,
and adopted for the bituminous layer from MoWT (2010) design guide recommendations in table 5.2
also attached in appendix 2D . Table 30 indicates the layer coefficients selected for calculation of the
structure number in the same table.

m2 and m3 are the drainage coefficients for the base and sub base respectively; based on quality of
drainage and percent time the pavement is to be exposed to moisture approaching saturation. These
were selected in accordance with the AASHTO (1993) recommendations as indicated in table 30 for the
same.

The selected values of the layer coefficients and drainage coefficients were appropriately substituted in
equation (3) to calculate the SN for the designed pavement structure. Table30 indicates the calculations
and the resulting structure number.
Table 29: Structural Numbers for the pavement alternatives.
Pavement Alternative Parameters SN
Based on:
a1 D1 a2 m2 D2 a3 m3 D3
MoWT (2010) Design 0.35 2.0 0.14 1.4 8 0.11 1.35 7 3.31
Manual (Chart 1)

The calculated SN = 3.31 is slightly greater than the required design SN = 3.3. Therefore the pavement
structure is adequate.

35
2.8.4 Pavement Alternative Based Overseas Road Note 31 (ORN31) Guidelines
ORN 31 design guide considers traffic and subgrade strength to select pavement design structure from
the relevant charts in the design catalogue forming part of the same guide. Like the MoWT (2010)
design guide, ORN31 recommends for a pavement structure for design traffic class and subgrade
strength class.

Like in the case of MoWT (2010) design guide, the traffic class for the estimated CESAL in subsection
2.5.6.4 was T5, and subgrade strength class was determined to be S4 corresponding to the design CBR
value determined in subsection 2.4.5.

Accordingly, Granular Base/Granular Sub base with Double Surface Treatment was appropriately
selected as the pavement structure all in accordance with the recommendations of chart 1 forming part
of the catalogue of pavement structures in the design frame work of ORN31. Details of the respective
pavement layer thickness as selected from the chart are indicated in table 31.

Table 30: Pavement alternative (ORN31)

Traffic Subgrade Class Pavement Structure alternative base on ORN 31, Pavement Design Manual
Class adopted Catalogue of structures (Chart1)
T5 S4 Double Surface Treatment
200mm Granular Base
250mm Granular Sub base

2.8.5 Pavement Alternative structure number

Similarly for the alternative, I estimated the structure number to be 3.26 ≈ 3.3 as indicated in table 32 by
substituting in equation 2 the recommended selected values of the respective layer thickness, layer
coefficients, and drainage coefficient.

Table 31: Pavement structure number (ORN31)

Pavement Alternative Parameters SN
Based on:
a1 D1 a2 m2 D2 a3 m3 D3
ORN31 0.2 1.0 0.14 1.4 8 0.11 1.35 10 3.26 ≈ 3.3

The calculated approximated to SN = 3.3 is equal to the required design SN = 3.3. Therefore the
pavement structure is adequate.

Selection of the better alternatives was recommended based on the results of the total life costs for the
economic analysis. Subsequently, the most economical alternative was recommended for consideration
by the client.

2.8.6 Cost Considerations.

For each of the pavement alternative, I estimated the preliminary construction estimates for input in the
assessment of the life cycle cost. The T.o.Rs required for preliminary quantities estimate with an
accuracy of ± 20% (twenty percent) for the proposed road construction and improvements and
preliminary cost estimates of road construction.

36
In accordance with the terms of reference, I developed the unit rates, estimated the preliminary
construction quantities, and the cost estimates for the pavement designs.

I adopted the unit rates from recent similar projects and I made a comparison of different projects rates;
hence informed establishment of construction costs with the required degree of accuracy.

The costs were based on the Preliminary Construction Quantities I determined the construction
quantities for the main items of work as indicated in table 34. The same table 34 indicates the cost
estimates determined for the design alternatively.
.
Table 32: Construction estimates for construction works
Work Item 50mm Asphalt Pavement DBST
SERIES as per MoW&T General Specifications AMOUNT AMOUNT
1000 GENERAL 309,264,761 309,264,761
2000 DRAINAGE 574,702,626 574,702,626
3000 EARTHWORKS AND PAVEMENT LAYERS OF GRAVEL OR 2,763,018,108 2,763,018,108
CRUSHED STONE
4000 BITUMINOUS LAYERS AND SEALS 3,112,069,542 1,175,891,840
5000 ANCILLARY ROADWORKS 332,364,418 332,364,418
7000 TOLERANCES, TESTING AND QUALITY CONTROL 55,000,000 55,000,000
8000 DAYWORKS (ALL PROVISIONAL) 279,659,440 279,659,440
SUB-TOTAL 7,426,078,896 5,489,901,194
ALLOW 10% WORKS CONTINGENCIES 742,607,890 548,990,119
SUB-TOTAL 8,168,686,786 6,038,891,313
TOTAL 8,168,686,786 6,038,891,313
Rate per km of Road 1,128,271,655.48 834,101,010.15

The design alternative according to ORN 31 allows for the road investment at a reduced initial
construction cost. However, selection of the final alternative I recommended for the roads was based on
the results of the life cycle costs determined for the respective alternative during the economic
assessments for the project.
2.8.7 Recommendations on the Final Design alternative
The choice of the final pavement was based upon the results of the life cycle analysis for each of the
pavement. Accordingly, the results of the life cycle cost analysis revealed the pavement structure within
the MoWT (2010) design framework to be more economical and hence recommended for the KIBP
roads as detailed in table 33 for the respective layer thickness.
Table 33: Recommendations on Final Pavement Design Alternative
Proposed Pavement Design Reason
50mm Asphalt Concrete, The initial construction costs are higher for the option, however, the pavement
200mm of Lime Stabilised Base structure is slightly more structurally sound (higher SN at 3.31 compared
(G80) and 175mm of G30 to 3.26).
Subbase, over well prepared
Roadbed.

37
 2.9 HYDROLOGY AND DRAINAGE DESIGN
Detailed design for KIBP allowed for protection of the proposed KIBP road from surface water and/or
ground water that could increase the susceptibility of pavement damage due to traffic loading in case of
entry and/or soaking respectively. Accordingly, I satisfactorily executed the following roles to ensure
effective and efficient drainage design. The resulting design aimed at shedding of rain water by the road
surface, avoidance of the pavement from ground water soaking due to level of local water table, and
effective drainage of water from within pavements in case of infiltration during service life of the road. .

I designed the cross section for the roads alignment at recommended minimum cross slope values or
better to ensure effective shedding of rain water. 2.5% slope was specified for the carriage way, and 4%
for the shoulders all in accordance with MoWT (2010) for the same. The resulting cross section will
ensure that the rainwater falling on the road is shed harmlessly over the shoulders provided the
bituminous surfacing and shoulders are properly maintained.

I allowed for adequate width of pavement layers for effective drainage of water from within pavements in
case of infiltration during service life of the road. The road base and sub base widths allowed the
respective permeable pavement layers to extend right across the shoulders to the drainage ditches.

I reviewed the work of the hydrologist to ensure satisfactory design of the cross drainage system and
side drainage systems, for the works. The hydrologic surveys from which the design flows were
estimated, and the hydraulic analysis that resulted in the sizing of the side drains and cross culverts
were all carried out by an experienced hydrologist and in accordance with the relevant and applicable
prevailing best practice and principles. Thus, production of detailed design for the KIBP road network
based on a valid assumption of a properly designed and correctly functioning side drains and cross
culverts that form part of the good drainage system to ensure successful operation of the road network.

The following drainage requirements that ensure an effective and efficient cross drainage were
addressed for the detailed design of KIBP roads:
 Culvert Alignment was satisfactorily recommended along the natural drainage line; and where
conditions called for skewed alignments, a reduced degree of skew angle not exceeding 45
degrees as measured from a line perpendicular to the roadway centerline was recommended to
shorten the culverts and reduce costs.
 Culvert Gradients was satisfactorily recommended at the standard minimum gradient of 2%;
 Minimum size of culverts was satisfactorily selected at 900mm by comparing the sizes obtained
from hydraulic design principles to the minimum sizes required by practical aspects of
construction to avoid maintenance problems and clogging.
 Culvert End Structures were adequately allowed for to prevent scouring of the roadway
embankment, provide a transition from a channel to the culvert, and to improve the hydraulic
performance of the culvert.
 Culvert Schedule was appropriately established. The detailed culvert Schedule is shown in
Appendix 2E.

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3. SUPERVISION OF ROAD PERIODIC MAINTENANCE.
3.1 INTRODUCTION
The Government of Uganda represented by the Uganda National Roads Authority (UNRA) contracted
Engineers Investments Limited (EIL) to carry out the periodic maintenance works for Katunguru –
Ishasha road in western Uganda. According to the works contract dated 26 th November 2012, the
contractor committed to implement the works in accordance with the contract constraints on; Scope
comprised of but not limited to medium grading, gravelling, drainage improvement works, and
bituminous Surfacing all as outlined in the works contract Bills of Quantities (BoQ); Cost as determined
in the contract BoQ; Quality specified in the technical specifications for each of the BoQ work items;
duration with the original contract commencement on November 26, 2012 and completion in October
20, 2014 including 6 months Defects Liability Period (DLP); And Occupational Health Safety, and
Environmental (OHSE), all in context of the general specifications that formed part of the contract.

To assure herself that the works contract objectives are satisfactory met by the contract; UNRA hired
the services of KKATT consultant to oversee on her behalf the satisfactory achievement of the works
contract objectives. Accordingly, KKATT appointed me in the position of Assistant Resident Engineer
(ARE) to assist the Resident Engineer Eng. Kato Kagga in the day to day site supervision and contract
management aimed at achieving the planned works contract objectives, all in accordance with the
requirements of the service contract between the UNRA and KKATT that commencement in November
2012
3.2 SITE SUPERVISION AND CONTRACT MANAGEMENT ROLES
As ARE on site, I satisfactorily executed the following leading roles that satisfactory resulted in the
achievement of the planned works contract objectives.
 Work Inspections and Approvals;
 Personnel and Equipment Mobilization Inspections and Monitoring;
 Assessment of Material Test Results;
 Assessment of Completed Work Sections Test Results.
 Assessment of Variations in Quality.
 Issuance of site instructions as authorized by the RE;
 Advised on claims and variation orders;
 Called and Chaired site meetings;
 Carried out progress reporting;
 Carried out work Measurements and advised on payment;
 Observed and assessed the performance of the works during the defects liability period;
 Examined and advised on the work program updates;
 And Carried out Works Inspections in Defects Liability Period.

Throughout the performance of the tasks, I utilized the most economical, effective, and widely accepted
engineering concepts recommended for road works supervision all as discussed in the following
subsections for each of the site supervision and contract management activities.

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 3.3 WORK INSPECTIONS AND APPROVALS
The Works Contract required of the contractor to produce road works that conformed in quality and
accuracy of detail to all the requirements of the works contract specifications and drawings. Therefore,
during the works implementation, I regularly visited the site to inspect the quantity and quality of the road
works and approved or advised on the approvals before the contractor could proceed with certain critical
activities such as gravelling works and bituminous carriage way and shoulders.

In addition, I inspected to ensure that the methodology of works execution for the respective contract
work items was in accordance with the contract technical specifications in section 6 of the Contractor’s
Works Contract and the BoQ.

Table 35 indicates the responsibilities performed during the day to day quantity and quality site
inspections. Photographs in figure 7 indicates the progress pictures taken during implementation of
quality control activities.

40
Table 34: Quality and Quantity progress Inspection activities and Objectives.
SN BOQ work item Responsibilities Performed. Remarks.
Operation inspected
1. Setting out and Site  Inspected and ensured the following Site Clearance quality control objectives;  Setting out of the alignment was not
Clearance  That the contractor adequately mobilized prior to start of the activity; applicable since these were maintenance
 No grass or top soil was left after progressive bush clearing of sections. works following the existing alignment.
 The contractor achieved the contract specified clearing width of 9m.
 The contractor disposed the debris with no possible risks of washing back in the drains during rains;
 Satisfactory productivity of activity execution in terms of rate of progress.
2. Reshaping by Medium  Inspected to check and advise to ensure the following objectives:  The Key equipment and Tools used included
grading.  The contractor adequately mobilized the required resources for proper execution of the activity in Grader, Roller, Water bowser
accordance with the specified work method;  The width of the road formation was checked
 The road way width and the side drain dimensions conformed to the specified width of 7.0m for the by tape measure at every 100m interval.
roadway and 1.0m for each road side drains all as checked by a tape measure;  The camber was frequently checked using a
 The specified cross fall of 4% in the drawings was achieved for sections as checked by the camber camber board/a dump level;
board.  At least 8 passes were made at medium
 The mitre drains’ locations and dimensions were as per the issued instructions; grading which ensured satisfactory
 The longitudinal profile was smooth without unnecessary undulations; compaction subject to compaction testing.
 Counted the roller passes to ensure compaction and that no visible roller imprints were visible in the
finished sections;
 V-shaped ditches true to dimensions as specified in the drawings;
 Adequate ditch invert gradient at all times to minimise drainage problems and water flowing to the wrong
directions;
 The slopes were correctly cut true to grade and line,
3. Gravelling Works  For the gravelling operations, I inspected to ensure the following quality objectives:  The sequence of actual gravelling works
which included  Borrow sources were satisfactorily cleared and overburden removed; involved excavation of gravel material from
provision of gravel  Gravel was supplied from only approved sources; approved sources, Hauling, Placing and
material of acceptable  Remove of oversized particles and other unsuitable materials like roods were removed from the spreading, Processing and compaction to
quality, transportation, excavated materials prior to its haulage and also processing; 95% MOD AASHTO;
processing, and  Trucks were satisfactorily loaded to the correct line with no oversize particles and roods included;  The Equipment and Tools used included;
compaction into  Sections at formation were satisfactorily reshaped and moist prior to dumping of gravel specially for Grader, roller, water bowser. The quality
150mm thick Gravel sections exposed for 1 to 2weeks at formation , tools used were Taper measure and camber
Wearing Course  The gravel was dumped at the predetermined spacing of 5m based on the capacity of the trucks used; board
(GWC):  The width was checked at a frequency of
 Dumped gravel was timely spread immediately after dumping;
100m as the gravel processing works

41
SN BOQ work item Responsibilities Performed. Remarks.
Operation inspected
 The gravel was processed to the specified layer width of 6.0m; progressed;
 The thickness of the GWC was 150mm as specified contract specifications;  The thickness was checked through
 The cross slopes at GWC was 4% as specified in the contract, excavation of test holes (200m interval) and
 The longitudinal profile was satisfactorily smooth without unnecessary undulations; measuring with the tape measure;
 The compaction was visually satisfactory without any random roller tyre imprints in the completed  The cross fall was checked using a camber
sections; board/a dumpy level.
4. Bituminous Carriage  Inspected to ensure achievement of the following quality control objectives;  The bituminous surfacing was applied to only
way and shoulders  Satisfactory mobilization of resources prior to commencement of bituminous works operations; the steep gradient section between 27+000
 Scarification of existed pavements to depth specifications (150mm) and proper disposal of cut to spoil; to 29+000;
 Proper spacing of lime bags for the stabilized base;  The tools used to check the quality of works
 Proper processing of stabilized base to uniform colour after stabilization; included; Tape measure,
 Roller Tyre Imprint free completed base;
 Dust and loose material free gravel base prior to priming;
 Application of bitumen (both Prime and Tack coat bitumen at recommended temperatures;
 Application of respective bitumen grades at the specified application rates
5. Drainage operations  Inspected to ensure achievement of the following quality control objectives;  Quality Tools used during the routine
which included among  Culverts installation at the specified grade (2%), and true to line; inspections included; Tape measure, Dump
others culvert  Culverts installation to specified length (ranged from 6m for access culverts to 9m cross culverts and level, Visual Observations.
installation skewed;
 Defective free culverts installation;
 Culvert joints sealed

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Checking the width of formation works with a tape measure Adherence to the methodology of medium grading.

Perfomance of the borrow pit operations Lightly reshaped and moist surface at formation being
dumped with gravel.

Dumping of gravel at 5m spacing between murram heaps Picking of oversized particles from gravel during the
adequate to yeild 150mm thick gravel wearing course. processing of the GWC.

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Processing of the Gravel wearing course Compaction of the GWC to remove the roller tyre imprints.

Witnessing the random excavation of trial holes to measure Measuring the thickness of the GWC with a tape measure.
the depth of the GWC as its laid and processed.

Measuring the width of the GWC with the tape measure and Measuring the camber with a dumpy lever
the cross fall with a camber board.

44
Inspection of the spacing of the lime bags and the Gravel Stabilized base being cleaned of dust and loose
methodology of mixing. material.

Clean gravel base surface being primed as I visually observed Witnessing the stone chipping process days after the
the adequacy of the application and the same being measured priming activity
by the laboratory.
Figure 7: Progress Photographs for Quantity and Quality Progress Inspection Activities

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 3.4 MOBILIZATION AND PERFOMANCE OF RESOURCES.
In order to achieve the quality and quantity objectives explained in section 3.3, the contractor was required
to mobilize specified key personnel and Equipment which he committed in the works contract in section 9.2
and 9.3 respectively at the bidding stage. Accordingly, I inspected the contractor’s personnel and equipment
mobilization which ensured adherence to the contract requirement for the same resources.

In addition, I observed the performance of the mobilized personnel and equipment to ensure effective and
efficient works implementation. Whenever, the contractor’s mobilization for key equipment and personnel
was found unsatisfactory, I drafted up letters informing the contractor of the inadequacy and the potential
consequence that may accrue to him because of the continued inadequacy in the mobilization. The letters
were reviewed and issued to the contractor to which he always positively responded. For the mobilized
machines, which I found to be faulty were suspended off the site and replaced by better machines which
were in a mechanically better sound condition.

Furthermore, I inspected to ensure that the contractor timely mobilized the following tools for checking the
works quality during works progress; Dump level and Camber board for levelling purposes, Tape measure
for checking the accuracy of measurements for the works.

In addition, I drafted up letters reminding the contractor to mobilize the approved laboratory (MoWT Central
Materials Laboratory) that carried out the necessary quality tests.

Table 36 indicates the equipment mobilized by the contractor; Table 37 indicates personnel mobilized all to
completion of the project.

Table 35: Equipment and Personnel mobilized by the contractor to project completion.
SN Equipment Quantity Type Condition
1. Motor Grader CAT 140G 2 Caterpillar Serviceable
2. Chain loader D-6 1 Caterpillar Serviceable
3. Chain loader Komatsu 1 Komatsu D8 Serviceable
4. Excavator 1 Komatsu Serviceable
5. Vibrating Roller 2 Sany Serviceable
6. Lime Mixer 1 CAT Serviceable
7. Bitumen Distributor 1 Scania Serviceable
8. Mechanical Chip spreader 1 Serviceable
9. Pneumatic Roller 1 Sakai Serviceable
10. Water Tank 2 TATA Serviceable
11. Tipper Trucks 10 TATA (4nos) and ISUZU Serviceable
(6Nos)
Table 36:Personnel Mobilized by the contractor to completion of the project
SN Equipment Designation Input
1. SivaKoti Reddy Project Director. Part time
2. Dexter Macatipon Project Coordinator Part time
3. George Oganda Site Agent. Full time
4. Namara Edward General Foreman. Full time
5. Will Fred Lubega Plant/Equipment Manager Full time
6. Robert Mudhumba Surveyor. Full time
7. Dexter Macatipon Project Coordinator Part time

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 3.5 ASSESSMENT OF MATERIALS’ TEST RESULTS.
The works contract required the contractor to have conducted test on a regular basis to check the properties
of natural materials specially Gravel. Accordingly, I visited the site to witness the performance of all such
quality tests including sampling and testing of potential gravel borrow pits; compaction testing of the road
formation, granular sub base and base course and the gravel wearing course, and bitumen spray rate
testing. Consequently, all the materials incorporated in the permanent works were tested. Such materials
included among others; gravel, lime, aggregates, and bitumen among others.

In addition, I timely reviewed all the resulting test results as submitted by the contractor for compliance with
the contract specified quality requirements. For satisfactory test results, I drafted up formal approvals for the
materials which were issued to the contractor by the Resident Engineer (RE). For unsatisfactory results, I
drafted up letters formally advising the contractor to source for better quality materials.

The materials were assessed in accordance with the standard requirements for the respective materials as
specified in the Contract General Specifications for Roads and Bridges (2005).

3.6 ASSESSMENT OF COMPLETED WORK SECTIONS’ TEST RESULTS.

The works contract specified the quality requirements for all elements of the Works that were completed by
the contractor from time to time. Accordingly, I inspected to ensure that the contractor performed the
specified tests on completed works section especially at road bed and gravel wearing course.

In addition, I assessed the resulting test results as submitted by the contractor for compliance with the
contract specifications for the same. In order to achieve the inspection objective, I attended to the
performance of the relevant field tests and/ or ensured attendance by the supervision team materials
technician.

The test results reviewed included; Compaction test results at formation for section from 0+000 to 87+000;
Compaction Test results at Gravel Wearing course for sections from 0+000 to 27+000 and from 29+000 to
87+000; Compaction test results at sub base for section from 27+000 to 29+000, Compaction test results at
granular base for section from 27+000 to 29+000.

3.7 ASSESSMENT OF VARIATIONS IN QUALITY

During the works progress and the related quality inspections carried out, I observed that the performance
of marginal gravel material from an approved borrow pit at 52+000 offset 10km from the project road was
not performing satisfactorily after the contractor had gravelled 1 km using the gravel material from the
source. Immediately I drafted up a letter, advising the RE to issue the same letter to the contractor
instructing to stop using the material and source other better quality gravel sources which was effected
immediately.

3.8 ISSUANCE OF SITE INSTRUCTIONS.

Communication in contract administration is key to smooth management of any contract. The Works
Contract specifications required for the contractor to request for site instructions and the same works
contract (GCC clause 23.1) required the contractor to carryout out all the instructions issued to him by
KKATT as the supervising consultant.

47
Accordingly, I assessed the contractors requests for the site instructions prior to drafting the required
instructions that were letter approved by the RE prior to their issuance to the contractor. For instance, the
contractor requested to proceed with medium grading of the whole of the road works (0+000 to 87+000) at
the commencement of works, however, I advised the RE that the contractor be instructed to carryout
medium grading in sections which should be gravelled first prior to a subsequent instruction of medium
grading in other sections to avoid contract front loading and overexposure of sections at medium grading
without timely gravelling of the same.
Accordingly, the contractor was instructed to carry out the activity starting from 0+000 to 20+000, and
another instruction for the activity was issued after the contractor had finished grading of the section and its
subsequent gravelling hence avoiding front loading of the contract and over exposure of road sections by
allowing the grading and gravelling activity to proceed simultaneously.

In addition, I drafted up site instructions for the contractor to correct or make amendments to the work
details; use the provision sum for quality control testing; and remove improper work or materials.

All the site instructions were issued in writing in triplicate using standard recommended formats. I kept
records of signed copies of the site instructions as acknowledged by the contractor’s site agent on the site
for future reference. Additionally, the contractor was instructed using formal letters drafted up by me and
approved for issuance by the RE.

3.9 ASSESSMENT OF CLAIMS FOR CONTRACT VARIATIONS.

During the Works Progress, the contractor discovered that the gravel haulage distance was substantially
differing from the contract specifications. According to the notification, the contractor informed that the
haulage distance for gravel material from the only available borrow sources to some of the road sections to
be gravelled was in excess of the 20km specified in the works contract (Item 4.3.3 of the works contract
BoQs).
Upon the written notification, I carried out the following to advise the RE on the necessity for the variation
order, all in accordance with the relevant clauses of Contractor’s Works Contract specifications and the
Consultants Service Contract.
 I investigated the contractors Claim for potential over haulage of gravel.
 I drafted up a detailed assessment report to the RE as required by the Works Contract General
Specifications for roads and Bridge in clause 1201 e of the general specifications for roads and
bridges (205).
 In the report, I determined work sections to be affected in overhaul beyond contract specification.
Subsequently, I developed a strip map for sections in overhaul and those not to be affected by
overhaul which I later sent to RE for issuance to the client. The strip map and the corresponding
quantities in overhaul are attached in appendix 4B.
 Considering that the contract BoQ did not have an established rate for the overhaul item, I carried an
independent over haul rate analysis for recommendation to the client as that to be adopted by the
contractor. However, a slightly higher rate of Ugx 2500 was adopted for use after a management
meeting at the clients head office. It should be noted that the contractor initially proposed a higher
rate of 3500 and he was objectively convinced to adopt the lower rate of Ugx 2500 based on my
detailed rate analysis.
 Having confirmed the rate among the relevant stake holder, I drafted up a letter which was issued to
the contractor as the official communication of the rate as agreed to in the management meeting that
was attended by the contractor, client, and consultant including myself.
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  In addition, I draft up the minutes of the same contract management meeting within 24hours after the
meeting.
 With the over haul rate in place, I calculated the cost implication of over haul and drafted a
corresponding revised BoQ.
 I analysed the overhaul time implication to the contract.

3.10 MONTHLY PROGRESS SITE MEETINGS

In order to fulfil the major responsibility of monitoring works progress and handling site issues, I called and
chaired contractual monthly progressive meetings as authorized by the RE and in accordance with the
requirements of the Works contract and the Service Contract. Such meetings were used to assess the
contractor’s progress and provided a formal arrangement for checking the contractor’s performance against
the approved work program and provided on spot solutions to site issues. Additionally, I performed the
following activities all relating to such progress site meetings:
 I drafted up the invitations to any of the progress site meetings throughout the contract period.
 Prior to any of the progress site meeting, I prepared the monthly progress status report which was
used for communication during the site meetings.
 Whenever the RE chaired the meetings, I recorded the proceedings and prepared the meeting
minutes. The minutes were distributed to the client and the contractor within 24 hour after the
meeting.
 Finally, I followed up with the contractor or the rest of the supervision team to ensure fulfilment on
responsibilities for certain actions and decisions as agreed to in the progress meeting.

3.11 PROJECT REPORTING.

Both the works and works contract required KKATT to prepare reports as deliverables intended to provide
timely and relevant information to the client. Accordingly, I timely prepared reports as indicated in table 38
which were reviewed by the RE and thereafter submitted to the client.
Table 37: Details of project reports prepared throughout the contract period.
SN Report Timing/Frequency of Summary of Details
Report
1. Inception Report.  Within 1 month of  Back ground to the project;
Service contract  Location of the project;
commencement  Scope of works;
 Works contract Details;
 Consultants Work plan and Methodology;
 Project progress status at the time of reporting;
 Progress photographs;
 Progress issues; Progress on preconstruction approvals;
 Progress Meetings to the reporting date;
 Important issues requiring attention;
 Project risks, constraints and correction measures.
2. Monthly Progress  Monthly throughout The report covered all the whole project including:
Report the contract period.  A summary of progress on the contract;
 Work plans with amendments if any;
 A summary of expenditure to date;
 A forecast of future expenditure;
 A summary of contractor’s labour, equipment and materials

49
 SN Report Timing/Frequency of Summary of Details
Report
inputs;
 Comment(s) on technical problems, constraints, delays and
irregularities;
 A summary of the firm/consultant’s staffing inputs and
comment(s) on any consultancy shortcomings or problems;
3. Claim  Whenever the  Description of the varying conditions in respect with the
Assessment contractor lodged a contract specifications;
Report. claim for Variations in  Details of the potential cost consequences that arose from
the contract. the varying condition;
 Details of the potential time consequences that arose from
the varying condition;
 Rate analysis details;
4. Contract  On submission of  Works contract details;
Management Contractors Payment  Contract description;
Report Certificate.  Contract particulars;
 Contract setup detailing site camp establishment;
Contractors Plant and Equipment; Contractors personnel,
Material sources; Comment on work methodology
 Contractor’s progress to certified to the certificate at hand;
5. Materials Report  At works contract  Details of material sources,
closure  Assessment of the quality of the materials;
 Recommendations on the suitability of the materials;
 Cost implications that result from the use of the material
source
6. Final Completion  At Closure of Works  The report covered all the relevant technical and financial
Report Contract immediately details of the works contract
after completion of  Recommendations for maintenance;
DLP

3.12 MEASUREMENT AND PAYMENTS

Measurement and Valuation was clearly a prerequisite to certification of payments of works as governed by
the conditions of contract for the Bill of Quantities contract type. The conditions of the works contract and
works contract specifications specified the measurement guidelines, the unit of measurement, and the role
of the consultant in the checking and certifying the contractors certificates. As ARE, I successfully carried
out the following leading activities that ensured effective measurements and valuations for all the works as
progressively executed by the contractor:
 Whenever the contractor requested for joint measurements, I immediately notified to the contractor’s
site agent of my intention to measure the works at the times as suggested by him and found
appropriate by me, all as authorized by the RE.
 As agreed, I progressively jointly measured the completed works with the contractor site agent who
doubled as the site engineer;
 I continuously kept on file a record of such measurements carried out;
 From the measurements, I derived quantities that formed the basis for all the prepared interim
certificates that I prepared and later submitted to the RE for review and subsequent submission to the
client.

50
  As a result of the joint measurements carried out, I identified at an early date, possible sources of
contention and drew these to the RE's attention such that he always properly prepared for any
situations that frequently rose.
 I drafted up the interim certificates attached to the contractor’s payment claims. The RE reviewed the
Interim certificates and forwarded to the client recommending for payment to the contractor in the
amounts as assessed by me on his behalf. The Interim certificate showed the value of the permanent
works measured as satisfactorily executed by the contractor up to the previous period as well as the
estimated value of works completed during the month in question.
 During preparation of the interim certificates, i ensured that all funds paid by the client to the
contractor in justified advance payments especially shortly after works contract commencement, were
appropriately recovered from the progress payments made to the contractor.
 Finally, I allowed for deductions for retention money and other percentage or lump sum withholdings
as specified by the contract specifications. The evaluation of Bill Items was in accordance with the
rates and prices in the works contract Bills of Quantities.

3.13 REVIEW OF THE CONTRACTOR’S WORK PROGRAM AND THE PROGRAM UPDATES
Under Clause GCC 27.1 & 27.2 of the Conditions of the works contract, the Contractor was obliged to
submit a programme of works and its subsequent updates to the KKATT within 21 days of works
commencement and after 28 calendar days respectively. Accordingly, I performed the following leading
roles that ensured compliance by the contractor;
 I timely drafted up a letter reminding the contractor to timely submit the revised program of works
within a month of contract commencement. In the letter, I reminded the contractor to prepare the
program in accordance with the relevant contract requirements for the same.
 On submission of the revised program of works and the program updates, I reviewed the same for
compliance to the contract requirements; then passed the review comments to the RE in good time
for the approval or disapproval depending how satisfactory I found the submissions.
 For the approved programs; I monitored the contractor’s performance against the same. I inspected
the contractors performance against the applicable approved to ensure works progress in a
satisfactory manner, mode, and speed of construction.

3.14 CROSS CUTTING ISSUES.

Road constructional activities should be implemented at the least construction cost while maximizing social
benefits and minimizing social costs and environmental costs. In order to achieve the objective during the
works contract implementation, I monitored to ensure the contractor appropriately implemented for the
different road construction activities, the required mitigation measures that successfully minimised the
undesirable OHSE costs as discussed in table 39. In same table, I have discussed the roles I successfully
carried out to ensure that the contractor addressed the gender issues on site; and that effective measures
were in place to ensure control of spread of STD/AID between the contractor’s work force and the local
communities within the project area.

Table 38: Roles performed in Implementation of Measures that satisfactorily addressed the Cross cutting Issues.
Role performed Discussion of actions Taken to ensure compliance of the Contractor
Recommended on  I drafted letters that enforced the contractor to timely submit all the respective plans within
adequacy of the the required 1 month after the commencement of works;
Environmental Protection

51
Role performed Discussion of actions Taken to ensure compliance of the Contractor
and Waste Disposal Plan  On submission of the OHS, HIV/AIDs and Gender Management Plan, I reviewed the
as submitted by the proposed plans to ensure inclusion of details on measures to Prevent and reduce
Contractor. accidents and injuries to the staff and workers and minimise health hazards to the adjacent
Recommended on community and general public; Prevent the spread of HIV/AIDS and STDs between his
adequacy of OHS, staff, labourers and the immediate Care for workers and staff who are infected with
HIV/AIDS and Gender HIV/AIDS and STDs; Encourage the recruitment of men and women as well as addressing
Management Plan as their specific gender working and living needs in the road construction environment;
submitted by the contractor.  I reviewed the environmental action plan to ensure that the contractor satisfactorily
outlined the potential environmental hazards and risks within content of the project, and
provided the action plan to deal with the hazards, minimise the risks and mitigate
adverse environmental impacts.
 After review of the respective submissions on such plans, I drafted letters to advise the RE
on whether to approve or disproval the submissions according to how i found them to
satisfactorily address the contract requirements the critical issues.
Monitored the contractor to I regularly inspected the site to ensure the contractor satisfactorily executed the measures as
ensure execution of the planned to protect the environment.
planned measures to  All construction roads surface no longer required by the contractor were immediately
minimise environmental scarified as needed to provide a condition which facilitated natural re-
degradation vegetation, provided for proper drainage, and prevented erosion.
 I inspected the locations proposed for the site camp and other workshops to ensure these
were located and established in a manner that preserved trees and vegetation as much as
possible and within the requirements of the national park rules;
 Prior to disposal of waste material like refuse, garbage, oils, and other petroleum fluids, I
inspected to ensure appropriate disposal methods and locations were approved for use by
the contractor in accordance with the contract specifications and the National Park
requirements;
 To avoid spillage, I inspected to ensure that the contractor carried out Servicing of the
construction equipment and all vehicles in only approved work station in and outside the
site camp. In addition, I inspected to ensure that the contractor ensured measures to trap
any spillage that that would potential contamination and or pollution of the environment
especially for servicing activities outside the approved workshop areas.
 For any of the gravel borrow pits used, I often drafted letters reminding the contractor to
progressively restore the same immediately after borrow operations. Accordingly, the
contractor was only authorized to demobilize after successfully restoration of the same
borrow pits and scarification of the haul access roads all in accordance with the contract
specifications and requirements of the National Park (NP);
 Inspected to confirm that the contractor’s pipe work installed for collection of solid waste
and sewerage to appropriately located and excavated soak pits was adequate. Approval to
use the same was based upon satisfactory installations all in accordance with the contract
specifications and the NP requirements.
 I instructed the contractor to timely excavate open drainage as the grading works
progressed. In addition, i inspected to follow-up on the issued instructions. This prevented
the potential for concentrated flows that would result in erosion;
 I inspected to ensure that the offshoots that formed part of the open drainage were flushing
at the end to avoid erosion;
 Inspected the contractors site from time to time, to ensure that there was accumulation of
waste material and rubbish especially in the site camp and around any storage areas
 Throughout the supervision, I instructed the contractor to spread all the windrows all to
prevent erosion.
 I ensured that the contractor equipment were in such a sound condition to minimize
pollution. I advised the RE to expel faulty equipment off the site.
 On works completion by the contract, I inspected to ensure that the contractor was only
allowed to demobilize upon satisfactory removal of all temporary buildings including
concrete slabs and all unused construction material and debris. In addition, I ensured that

52
Role performed Discussion of actions Taken to ensure compliance of the Contractor
the contractor scarified the surfaces especially in and around camp are to allow nature re-
vegetation and to such terrain that minimized erosion.
 For any deviations from the plan, I drafted letters to notify and caution the contractor on
such deviations,
Monitored performance of I inspected the site to ensure that the contractor implemented the following measures that
the contractor in the ensured as far as was reasonably practicable, the health, safety and welfare of the
execution of measures contractors employees; those of his subcontractors; and of all other persons on the Site.
planned to reduce the  The contractor liaised with Uganda World Life Authority and any other relevant
potential occupational government organizations and local authorities to ensure safety of the work force,
health and safety hazards. considering the wildlife working conditions presented in NP environment.
 The contractor mobilized and regularly maintained the construction equipment to reduce
health risks hence improved heath.
 Only trained and experienced persons were involved in bituminous works and operated the
machines;
 Execution of suitable arrangements for ensuring safety and absence of risks to
health in connection with the use, handling, storage, transport and disposal of articles
and substances.
 The contractor satisfactorily provided protective clothing and safety equipment to all
staff and labour engaged on the Works that required the same. For instance: - high
visibility vests for workers directing traffic; protective boots, gloves and masks for
the workforce performing bituminous pavement works;
 The Contractor provided and maintained safe access to all places on the Site in a condition
that was safe and without risk of injury.
 Provision of safe passage around and through the work site for all kinds of traffic,
including non-motorised traffic and pedestrians; Traffic signs, and barriers were
satisfactory used for direction and control of traffic and to informed drivers of the
importance to slow down and drive carefully, all aimed at minimizing accidents;
 That the contractor provided adequate waterborne sanitation; and refuse collection and
disposal on site including all houses, offices, and workshops erected on the site camp.
 That the contractor provided adequate number of suitable latrines and other sanitary
arrangements.
 That the contractor provided mosquito nets to all his staff considering the site camp was
located in Queen Elizabeth National park.
 The Contractor timely reported details of any accident to the supervision staff, and the
Uganda Police.
 That the contractor provided shades at stationary work places and at welfare facilities;
 The contractor ensured park inductions to the work force;
 That the contractor provided adequate signing, fencing and guards to ensure that
unauthorised persons were kept off the site especially the dangerous parts of the
Site, e.g. borrow pits, bitumen boilers section, the storage areas for oil, fuel,
parking areas, the workshop, and near deep holes;
 The Contractor took the necessary precautions that avoided fire and health hazards
specially during the bituminous works like ensuring that the bitumen was heated only to
the temperature required for the particular application, suitable protective clothing and
gloves were used when handling hot bitumen;
 That dust and fumes were reduced to a minimum like through frequent watering in case of
heavy dust formation.
Monitored the contractors I inspected to ensure the contractor performed the following measures to combat the spread
performance against of HIV/AIDS and sexually transmitted deceases (STD) between the contractor’s staff,
planned measures to labour and the local community; all in accordance with the approved OHS, HIV/AIDS
ensure HIV/AIDS AND STD and Gender Management Plan.
PREVENTION  Non-discriminatory workplace site conditions that protected the employees living with
HIV/AIDS.
 Distribution of condoms to the workforce to protect against HIV/AIDS infection and

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Role performed Discussion of actions Taken to ensure compliance of the Contractor
transmission.
Monitored the contractor’s I inspected to ensure the contracted executed the following that allowed for Gender Sensitive
performance against the recruitment procedures and working conditions/facilities:
planned measures to  Equal employment opportunities notices posted in visible and popular places in the
ensure Gender sensitive respective local communities and that such notices also reached the women and local
recruitment and working leaders.
conditions/Facilities  Equal payment was made to men and women for similar work and that payment of
wages is made to the individual workers;
 Flexible working hours that took into account of multiple roles of women and cultural
norms where appropriate.
 Separate toilet and accommodation facilities were provided for women.
 Performance of the contractor was evaluated based of the attendance lists of works, and
visual observation of how the contractor addressed gender concerns in recruitment,
payment, provision of gender sensitive facilities, on-the-job training, all on site;
 I draft letters to caution the contractor in case of any non-compliance as found appropriate;

54
4. CONCLUSIONS AND RECOMMENDATIONS.
Following the successful implementation of the projects where I performed the leading roles as detailed in
the appropriate sections of the report, the following are the conclusion in accordance with the requirements
stipulated by UIPE and ERB for members desirous of registration with the engineering bodies in Uganda
and becoming a corporate member as well as a registered engineer.
 In the report, I have discussed the tasks successfully executed in engineering design, and
construction of road projects, as a highway engineer and an ARE respectively under the
supervision of Eng. Kato Kagga.
 Throughout execution of the tasks, I applied well researched standard and relevant engineering
principles based on the findings from the review of relevant literature including the sources
recommended by the client as well as the locally acceptable standard design manuals that have
successful been used for the same tasks, all as referenced in the appropriate sections of the
report.
 I have demonstrated my understanding of the engineering principles in the following stages of
detailed engineering design: Implementation planning; Traffic assessments; Soils and road
construction material investigations; Preparation of preliminary engineering design, Preparation of
Detailed Engineering road design, Quantification of work items based on the prepared designs,
costing to produce a construction estimate for a road project within the acceptable tolerances for
the respective stages of flexible pavement design.
 I also applied the management functions of planning, organizing, coordination, and controlling in
executing all the tasks I was responsible for. This is evident in all the appropriate sections of the
report like PPW development, supervision of traffic counts, and coordination of the laboratory
testing activity and supervision of road construction activities.
 In the report, I have demonstrated knowledge and indicated how the following cross-cutting issues
were addressed in the appropriate design stages, and road construction supervision: health, safety,
social, environmental and cultural aspects.

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5. LESSONS LEARNT
Having successfully executed the tasks assigned to, the following are the lessons learnt:
 Successfully implementation of the respective projects was achieved by performing of tasks in
adherence to the recommended phases of project management lifecycle of Initiation which is
concerned with definition of the project scope and the respective contract details, Planning;
Execution, Monitoring and control and closure.
 Proper planning prior to any project activity execution enhances the chances for successful
completion of any engineering project.
 Proper Detailed geometrical design is also justified by the huge unnecessary costs that may result
from having to correct the geometry of the road later lone.
 A satisfactorily prepared detailed designs mitigates the huge cost associated with a substandard
design inform of increased road accidents and loss of lives, and high fuel consumption.

56
BIBLIOGRAPHY
Central Materials Laboratory, Ministry of Works, Tanzania National Roads Authority. Field Testing Manual-
2003.

MoWT, Republic of Uganda, 2010.Road Design Manual, Volume1, Geometrical Design.

Ministry of Works, Housing and Communications (MoWT), Republic of Uganda, 2010.Road Design Manual,
Volume 3, Flexible Pavement Design, Part III.

MoWT, Republic of Uganda, 2005.Road Design Manual, Volume 2, Drainage Design.

Transport Research Laboratory TRL (2003). Maintenance management for district engineers. Overseas
Road Note 1. (3rd edition). Crowthorne, TRL Limited.

Transport Research Laboratory TRL (2005). A guide to Road Project Appraisal. Overseas Road Note 5.
Crowthorne, TRL Limited.

Yoder. E.J and Witczak, 1975. Principles of Pavement Design (2ndEdition), John Wiley & sons, Inc.
Canada.

57
APPENDICES

58
Appendix 2A: Project Implementation Plan

59
Appendix 2B: Project Monitoring Tool (Action Register)

60
Appendix 2C: Test Results from the DCP CBR Evaluation.

61
Appendix 2D: Design Charts, and Charts for estimation of Parameters.

62
Appendix 2E: Proposed Culvert Schedule for KIBP.

63
Appendix 2E: Proposed Side Drain Cross section, Design Considerations,
and Schedule.

64
Appendix 2F: Detailed Design Drawings.

65
Appendix 3A: Works Contract between UNRA and EIL

66