The Organization and Management of Construction 2 728 PDF
The Organization and Management of Construction 2 728 PDF
The Organization and Management of Construction 2 728 PDF
Management of Construction
SHAPING THEORY AND PRACTICE
VOLUME TWO
VOLUME TWO
Managing the Construction
Project and Managing Risk
Edited by
D.A. Langford and A. Retik
SPONSORED BY
E
glasgow
TheCHARTERED uk city of architecture
INSTITUTE OF + design
BUILDING 1999
GLASGOW
The publisher has gone to great lengths to ensure the quality of this reprint
but points out that some imperfections in the original may be apparent.
CONTENTS
Foreword xiii
Introduction to Volume Two xvii
PART I PRODUCTIVITY 1
1 Labour productivity 3
2 Productivity estimates 83
Integrating complexity
I.G. Jennings and R. Kenley 339
vIII Contents
2 Partnerlng 403
Index 907
FOREWORD
However, it was not until the late 1950s that the Institute, through the Board
of Building Education (BBE), established jointly with the NFBTE in September
1955, began to take action in recognition of the fact that 'in building as in other
industries, attention has hitherto been directed almost entirely towards
technology training and insufficient thought has been devoted to the problems
of recruiting, selecting and formally training individuals for supervisory,
managerial and executive responsibility. As a consequence there is an acute
shortage of men qualified to apply the principles of modern management
techniques to the conduct of building affairs'.
Management Studies for the Buildinq Industry, published by the Institute in
1959 is the seminal work laying the foundations for the modern Institute which
embraces management as its focus.
The syllabus, specified in this report and adopted by the Institute for its
examinations in the 1960s, was in three parts: Law, and Economics of the
Industry in the first year; Management in the second. 'Management' was
tackled both in principle and practice, with the latter having within the
'Production' segment the generic subjects of Construction; Purchasing; Plant
and Vehicles; Work Study; and Statistics and Sampling. It is interesting and
indicative to note that the supporting reading matter for the complete syllabus
was limited to about 30 titles, with only three of these being directed
specifically to construction.
It did not take long for the Institute to develop its own guidance for the
systematic teaching of building management subjects. In 1962, largely under
the direction of John Andrews, the Building Management Notebook saw the
light of day. For many it was the 'bible', with a new edition appearing in 1972 to
meet the demands of yet another change in the structure of examination
syllabuses.
The 1960s were a productive period for the Institute as its membership grew
and its influence extended. Recognition of the significance of management in
a modernizing industry had created a long lead over other qualifying bodies.
Having tackled management in generic terms it then, once again through the
BBE, looked at the needs of the construction site. The report Construction
Management in Building: Present and Future published in 1964 provided a
blueprint for the recruitment and training of site managers. Having identified
the increased demands placed on construction management the book
recommended 'a properly planned programme of education and training for
different levels of responsibility'. Ultimately, this objective was realised by the
creation of the Site Management Education and Training Scheme.
In 1970 a research project was initiated aimed at investigating the potential
for mid-career education and training of site managers. The study involved
widespread consultation and the subsequent development of pilot pro-
grammes, the first course of which was completed in 1972. This and
associated studies led to a proposal for a training scheme based on a series of
modules covering the skills needed in site management, leading successively
to a certificate and diploma. Implementation took place in 1976 with ten
colleges taking part. The scheme has continued to prosper and to fulfil its
Foreword xv
strategy for the Institute have anticipated their adoption by the industry itself.
Perhaps the most important, all-embracing objective is the desire to change
the way in which the industry regards research and innovation, for by doing so
it is believed that competitiveness and business efficiency can be substantially
improved.
The other key tasks addressed in the strategy relate to education -
incidentally in the Building Management Notebook referred to earlier it is
suggested that a one hour lecture should be adequate to cover research and
development - communications, priorities and international. The latter antici-
pates to a large degree a closer relationship with CIB and its Working
Commissions.
Much of the credit for the Institute's strategy must go to Dr Peter Morris, the
Committee's Chair and the keynote speaker for the 'Managing the Construc-
tion Project and Managing Risk' session.
I have attempted in preparing this contribution to highlight the CIOB's
involvement with, and support of, construction management. It is fitting to
conclude with the Institute's vision contained in Meeting the Challenge - a ten
year strategy for growth which was published in February of last year.
'Our vision is that, by the year 2005, the CIOB will be fully recognised as the
leading professional body for management in construction, thereby serving
society, the industry and its clients world-wide; and our members will be the
established leaders of the construction team.'
Peter Harlow
Innovation and Research Manager
Chartered Institute of Building
Ascot, Berkshire
April 1996
INTRODUCTION TO VOLUME TWO
To organize the range of topics covered by the W65 Commission the papers
have been structured into three volumes. Each volume focuses upon a
particular theme. These themes are:
• Managing the Construction Enterprise
• Managing the Project
• Managing Information
Within each theme there are sub-themes which collect together papers around
a specialist area of interest and then within each sub-theme there is a further
selection to collect together papers on similar topics.
This approach is intended to assist the reader in identifying and consolidat-
ing areas of special interest and to link together subjects appearing in each
volume.
Maintaining standards
In line with the growing confidence and maturity of the discipline, the papers
contained within the volumes have been subjected to exacting standards of
refereeing. Of the 241 abstracts received, 183 were selected for development
into full papers. All of the full papers received were then refereed and authors
invited to incorporate the referees' comments into their papers. At the time of
sending the material to the publishers 161 papers had been accepted. The
standards achieved ensure that the papers presented in the volumes are of a
standard expected in refereed journal articles.
Acknowledgments
Abstract
The cost of building new housing rose substantially during the eighties, which
resulted in high living costs despite substantial subsidies. A decision was taken to
reduce housing subsidies. This, together with a number of other factors has brought a
reduction in the demand for new dwellings. This has motivated substantial efforts to
develop building techniques so that the costs of housing can be reduced in newly
produced dwellings to a level which the consumer can accept. The reductions in costs
which are required are of such an extent that a completely new approach is required.
A company in Ljusdal, Sweden, has developed a form of construction using
factory-made precast concrete box units and carried out the first large project. The
aim of the chosen method is to reduce costs by improving quality, rationalizing
production, more efficient purchasing and shortening the construction time.
An evaluation and production economic analysis of the construction techniques
developed has been carried out. The evaluation shows good prospects for reducing
the costs of housing by means of precast box unit construction. Further development
work is required, particularly with respect to production techniques at the factory and
the design of construction parts which are to be connected to the precast box units.
Keywords: Precast concret, box units.
Sommaire
Les coats, pour la construction d'irnmeubles, ont augments sensiblement durant les
annees -80, ce qui a donne des coUts d'habitation plus important malgre des subven-
tions interessantes. Des decisions visant II baisser ces subventions, ont ete prises.
Ceci, ainsi que d'autres raisons ont conuit II une baisse de la demande d'habitation
nouvelle. Cela motive de grands efforts pour developper la construction et ainsi creer
des habitations nouvelles II des niveaux de coats acceptables pour les clients. Les
reductions necessaires sont II ce point etendues qu'iJ faudrait de nouvelles idees pour
attaquer Ie probleme sur tous les cotes techniques.
Un groupe d'entrprises II Ljusdal, Suede, a developpe un systeme d'element de
volume prefabrique en beton, et ainsi a deja realise un premier grand projet. Le but de
cette methode est de baisser les coilts, par une meillure qualite, une production ratio-
nalisee, des achat plus efficaces et une duree de travaux plus courte.
Une evaluation et une analyse d'economie de la production de cette technique a ete
realise. Cette evaluation demontre les bonnes possibiliees de baisser les coOts
d'habitations par une construction avec des elements prefabriques.Il est necessaire de
continuer II travailler sur Ie developpement, particulierement sur les techniques de
production dans les usines ainsi que sur la conception de pieces de la construction qui
vont relier les elements prefabriquees.
1 Introduction
1.1 Background and the project aim
The initiators of this development project, for which precast box units are used to
reduce construction costs, analysed 1990 costs for the project carried out and came to
the conclusion that there was a possibility of reducing construction costs by more
than 20%. They believed that this could be done by reducing the construction time on
The Organization and Management of Construction: Shaping theory and practice (Volume Two).
Edited by D.A. Langford and A. Retik. Published in 1996 by E & FN Span. ISBN 0 419 22240 5.
Precast concrete box units 5
site and with a high degree of prefabrication. This opinion was supported by others
during the general debate.
In brief, the project concept was that by producing precast concrete box units in a
factory, it would be possible to reduce the building costs to a competitive level. Pro-
duction could be made more efficient as a result of factory production, which would
not be affected by weather conditions and would also facilitate a high level of quali-
ty.The precast box units will be heat insulated and finish constructed at the factory.
The foundations consist of spot footings and beams which require minimal ground
work at an early stage. The greater part of the ground work is intended to be done
after the building is complete. The precast box units are primarily intended for
offices, hotels, detached houses and multiple-unit dwellings.
The overall aim of the development project is to further develop the sketched
production method of factory manufactured precast box units and to test it in a larger
project.
The economic evaluation of production, which is briefly presented in this paper,
should, among other things, answer the question whether building costs can be re-
duced by 20% with this method of production and, if so, in which way thesereduc-
tions in costs are accomplished compaired to a traditional production.
then found that the most important operations are those of handling and transporting
the precast box units, since the loading during transport is probably dimensioned.
B. The precast box units are designed.
C. Some precast box units are produced and test handled.
D. The precast box units are re-designed.
E. The precast box units for a student accommodation are produced as a pilot
project under accurate evaluation and a well developed quality assurance system.
F. The student accommodation is erected under strict control and follow-up.
G. The experiences of those who took part and those who evaluated the project
have been compiled with the aim of providing basic data for future production.
2.1 General
In the early developed solution, the structure was to consist of concrete columns and
beams on which the precast boxes would be positioned. The load-bearing beams,
which were intended to be installed at each level in order to prevent underlying mod-
ules from being loaded, could be omitted. During the development work it was
shown that a system of columns and beams was not necessary since the units could
be stacked on one another. It should be possible to construct the foundations with a
simple system of spot footings on which a columnlbeam system would be laid as
support for the precast box units. With the aim of keeping the weight of the concrete
to a minimum, high performance concrete was to be used in the precast box units.
~~~====~====~==~==~==~x
STUDENT ROOM
I
Figure 1. Plan of a student room, the student accommodation, Ljusdal. Drawing
made by Ljustech AB, Ljusd.~..
In Fig. 3. is a picture of the entrance-facade and Fig. 4. a section of the same build-
ing. The student accommodation contains 78 student rooms and approximately 90
room modules. In the student accommodation there are leisure, laundry, storage and
service areas for the property.
Figure 4. Section with comments regarding the formation of the Hammaren student
accommodation, Ljusdal,
Precast concrete box units 9
The student module is normally 4.4 m long and 5.4 m for the handicapped adapted
module. Each student module contains a toilet and shower, plus a refri- gerator. The
student modules are grouped around a corridor with a communal kitchen and
assembly areas.
3. Factory production
The precast box unit system transfers the traditional construction from the site's
craftsmanship-oriented production to an industrial operation. The way to solve tasks
and problems that arise is more in line with that applied in engineering industry.
From a material flow point of view the production of precast box units can be
adapted to the modern just-in-time philosophy.
To begin with, it should be pointed out that the forming of the factory and the
production system should be seen as a small part of the overall concept to be tested.
There was not enough capital available within the framework of this project to
completely develop and analyze the production apparatus.
The flow contains the following production operations or production stations, see
Fig. 5. In the same figure the time required to carry out each respective operation has
been given for a precast box with fittings the equivatent of those in the student
module. Precast box units with many installations can take longer time. The total
throughput time is, with dif-ferent installations and taking into account the drying
time before and after painting, 12-14 working days.
This method of production, with casting of the walls and roof simultaneously,
proved to form a restriction on versatility. Variations in size namely meant an
expensive rebuilding of the tunnel form. In future production a casting method will
probably be chosen which will involve the casting of the flat concrete units with cast-
in steel plates which are welded together.
The material flow of concrete has been adapted to the just-in-time philosophy by
the concrete being produced in line with the demand. Consequently instead of
reducing transport costs for the concrete trucks by linking several smaller concrete
castings together, as soon as a form and the reinforcement were ready on each little
stage they were cast and this was also done even if the batch cast was relatively
small. The quantities in each individual batch could be adapted exactly to the amount
required when casting. If the concrete was transported by truck it would have been
necessary to have a little extra in the truck.
Total 7 days
The cost of the precast boxes forms the dominant cost in the procuction with box
units. Two operations in the precast box unit concept are most important:
• The precast box units must, for economic reasons, be able to be mounted in position
immediately after factory production.
• The connection work following precast box unit erection must be carried out
quickly for both technical and financial reasons.
The prefabricated concrete units place special demands on the transport system
because of their size (for example with a maximum width of 3.8 m here compared
with a normally permitted 2.6 m on Swedish roads) The precast boxes coped with the
static and dynamic stresses during transporting without any mentionable problems.
The weight is 10-30 tons depending upon size.
During the concrete casting work the precast box is transported on its form and
supports which are used for casting concrete, and after that on a carriage equipped
with jacks with the help of which the precast box unit can be placed on trestles.,
The units are transported to the building site on a trailer. The carriage could take
two precast box units per trailer, Fig 6.
Figure 6. The units were transported between the factory and the building site on a
trailer drawn by a lorry.
100%
Precast concrete
box units
On site construction
Designing
Time
Figure 7. Principal figur showing use of resources during the time for production
with precast concrete box units and on traditional site construction respectively (here
showing a production of an hotel consisting of 40 room with a total time of 33 weeks
if on site production is chosen and 16 weeks for the alternative box units.
6 Quality assurance
A fundamental concept in the development project was that the production was
mainly to be carried out at a factory. As a result the quality required would be
ensured and the number of faults minimized. Factory production is also an important
prerequisite for being able, for example, to cast with high performance concrete.
For the production a quality plan was drawn up for production at a factory and
building site which was adapted to ISO 9001. The quality work at the factory and
building site was coordinated. Consultation meetings and self-inspection led to
continual improvement of the production.
An important hypothesis for the development group was, against the background of
the production method chosen, that the occurrence of faults on the work site should
be fewer than for traditional production. A survey of the examination report after the
final examination shows few faults internally in the room modules but a lot of dam-
age to the door frames and similar. Furthermore the survey shows that the total num-
ber of faults was no less than for a randomly chosen examination of a housing pro-
ject, which the same inspector carried out at approximately the same time as the
examination of this student accommodation. Types of fault noted in the report from
12 Hansson
the final examination are different for precast box unit production and traditional
production. Few faults occurred on the building site in the room modules. Those
which occurred were mainly due to faults in sealing in plastic during the construction
period. Quality assurance within the manufacturing had functioned well and the room
modules had left the production with few faults.
Figure 8. The cost for production using precast box unit and traditional on site built
respectively.
Precast concrete box units 13
assessment and calculation can be made of the total effects in the case of traditional
construction being carried out. The actual results of the municipal fees have not been
studied here.
8 References
Hansson B (1995) Precast concrete box units -production analysis, Department of
construction management, Lund University, Lund, Sweden.
THE USE OF CONVERSION FACTORS
FOR THE ANALYSIS OF CONCRETE
FORMWORK LABOR PRODUCTIVITY
U.E.L. de Souza
Department of Civil Construction, University of Sao Paulo,
Sao Paulo, Brazil
H.R. Thomas
Deparment of Civil Engineering, Pennsylvania State University,
University Park, Pennsylvania, USA
Abstract
Labor productivity management is important to the success of a project. The
concrete formwork operation is a labor intensive task ([1], [2], [3]) which influences
substantially the total cost of construction ([1], [2], [4], [5]).
Traditional cost systems follow a time consuming routine that includes: the break
of the work in pieces (items); the measurement of the amount done and the
workhours spent for every item. In doing so, several times one commits mistakes in
assigning workhours to each item. The "conversion factors" (CF) are used to avoid
this problem and to create an easier way to measure productivity. They estimate how
much easier (or more difficult) different formwork situations may be, identifying the
relation between the effort (expressed as workhours) necessary to accomplish one unit
of a certain item and the effort necessary to accomplish one unit of a standard item.
This paper presents the calculation of CF related to form work for walls and
columns. The following steps were followed: collection of productivity rates for
cases presenting different factors affecting the performance, from American
estimating manuals; choice of the most important factors in explaining productivity
variation; definition of a standard item for formwork (steel framed plywood panels
for walls until 8 feet height); definition of equations to estimate the CF for any non-
standard item of form work.
Since the CF has been calculated, one may transform quantities of any item in
equivalent quantities of the standard item. And then, measuring only the hours spent
on the work as a whole (the formwork in this case), its productivity can be
evaluated.
Keywords: construction management, conversion factors, labor productivity, work
measurement.
The Organization and Management of Construction: Shaping theory and practice (Volume Two).
Edited by D.A. Langford and A. Retik. Published in 1996 by E & FN Spon. ISBN 0419222405.
Conversion factors for analysis 15
Sommaire
La gestion de la productivite est cruciale dans Ie succes d'un projet La
realisation de coffrages est tres couteuse en temps et en hommes ([1], [2], [3]),
et pese en consequence sur la globalite des couts des travaux ([1], [2], [4], [5]).
Traditionnellement, les systemes de couts observent des procedures
particulierement chronophages dont Ie detail du travail en items et Ie calcul
du travail et du temps fournis par item. TI n'est pas rare, au cours de ces
operations, de faire des erreurs d'attribution des heures/hommes par item.
Pour circonvenir ce probleme et creer un instrument de mesure de la
productivite plus facile a manier, on a recours aux "facteurs de conversion"
(CF). TIs evaluent Ie degre de difficuIte de la realisation du coffrage en
etablissant Ie lien entre l'effort necessaire (en heures/hommes) a la realisation
d'une unite d'un item particulier et l'effort necessaire a la realisation d'une
unite d'un item standard.
Ce papier presente les calculs de CF propres au coffrage des murs et
des colonnes. Les etapes en ont ete : recueil, dans des manuels d'evaluation
americains, des taux de productivite pour des cas presentant des facteurs de
natures diverses influenc;ant les performances, definition d'un item standard
pour Ie coffrage (panneaux de contreplaque a cadre acier pour des murs
allant jusqu'a 2m de hauteur), definition d'equations permettant d'estimer les
CF pour tout item non-standard.
Sur la base des CF calcules, on peut alors se permettre de convertir les
quantites propres a n'importe quel item en quantites equivalentes de l'item
standard. Et ainsi, par Ie calcul des heures fournies pour la realisation
globale du coffrage (pour Ie cas qui nous interesse ici), sa productivite peut
etre estimee.
16 de Souza and Thomas
1 Introduction
For the purposes of this paper, productivity is measured by means of the unit rate,
that is defined [6] as the relation between the inputs (workhours) and the outputs
(amount of work done) of ajob. The inputs are measured in workhours (wh) and the
outputs in square feet (st).
The effort to complete 1 sf of form work may vary according to several features
like: the system used; type of element (column or wall, in this case); height of the
element; etc. To take these features into account, one has to defme a standard
condition and calculate correction factors to transform quantities of any other
condition into equivalent "units" of the standard one.
The conversion factor (CF) allows this transformation [6]. It is expressed as:
where:
CF(j) = conversion factor for condition "j",
unit rate(j) = unit rate for the condition "j",
unit rate(std) = unit rate for the standard condition.
2 Formwork classification
To allow the deftnition of conversion factors, one ftrst needs to defme a framework
at the same time comprehensive (to include as many types of formwork as possible),
simple (avoiding excessive slightly different classiftcations), and easy to understand
(avoiding misuses and inducing its use).
conversion equivalent
quanti1les factors quantities
~ w.l
comparison
to
SUM
the equivalent
quantities
~t8nd8rd Co
c.;
Figure 2 shows the framework used to classify wall and column formwork and to
calculate the CF. The ftrst division is related to the element being formed (wall or
column). The second division defmes the following broad categories:
- for walls:
* stick (#) = built-in-place formwork;
* non-stick (N#) = prefabricated (both in-site or out-site);
- for columns:
* stick (#) = built-in-place;
* non-stick rectangular (N#rec) = prefabricated (both in-site or out-site) with
rectangular section;
* non-stick round (N#rou) = prefabricated (both in-site or out-site) with round
section.
These terms, that represent a compromise between the simplicity and accuracy, ftts
the methods and the language used in construction. More than it, this division is
necessary to create groups of forms whose productivity is expected to be influenced
by the same factors (for example, "#" must be isolated from "N#" to study the
influence of "ganging panels").
18 de Souza and Thomas
The several levels below the two divisions represent factors (for example "height")
that have influence on the classes defmed by each vertical line (for example, "C#").
As a consequence of such a division, there are factors that have influence on one
category of fonn but not (or have a different influence) on another (for example,
"height" may have influence on the productivity of "C#" but not of "CN#rec").
other
factors
I--+----+----+---+_ t.i
conversion factors equations
The fonnwork job may be done under different kind of "factors" (as previously
shown on Figure 2); to describe a case, one must detect and quantify the existing
factors. The standard case is the one chosen as the gauge for comparisons. The
chosen case should be the most often used in practice in order to: improve the
accuracy of the comparisons; simplify the understanding of equivalent quantities
estimated using this standard.
The features of the standard condition for fonnwork were chosen as: fonn for wall
non-stick, with height not exceeding 8', and using plywood as surface material.
Although the procedures to get the data are sometimes not well understood, and may
vary from one manual to another, the estimating manuals represent an accumulated
experience extremely significant. Mainly because to collect data in construction is
neither an easy nor a cheap task.
Each case presented by a manual, expressed in tenns of accumulated unit rate at
the completion of the project, represents an average of the results obtained for similar
conditions in several sites.
Conversion factors for analysis 19
The following criteria were used in order to choose the manuals to serve as source
of data: to be recognized by the technicians as a good manual; to describe in detail
the cases analyzed; to avoid the use of manuals with the same origin.
The five chosen manuals were: "Structural Concrete Cost Estimation" [7]; "The
1984 Berger Building & Design Cost File" [8]; "1988 Dodge Unit Cost Data" [9];
"Means Man-hours Standards" [10]; "General Construction Estimating
Standards"[ll].
Table 1 shows how many cases were collected from each manual, while Table 2
shows the kind of information provided by the manuals.
Table 1- Number of cases collected in the manuals, for walls and columns.
Manual Element
wall column
Clark: 2 1
Berger 48 32
Dodge 12 43
Means 21 52
Richardson 104 24
TOTAL 187 152
The data collected from the Manuals expressed productivity in terms of unit rates for
each case. The transformation of this information into conversion factors followed the
20 de Souza and Thomas
steps: the cases were classified according to the "categories of fonnwork" previously
defmed: column stick, column non-stick round, column non-stick rectangular, wall
stick, and wall non-stick (generating five subset of data); for each subset it is
necessary to detect which Manuals have the standard as a case; when the Manual has
the standard, CF=1 is assigned to this case and the CF's for the remaining cases of
this Manual are calculated according to the defmition previously explained (ratio of
unit rates); when the Manual doesn't have the standard as a case, it is necessary to
calculate the unit rate for a "estimated" standard (the unit rate for the standard if it
was present in the subset), and then the CFs for all the cases are calculated in the
same way just described. In order to estimate the standard unit rate it is necessary
to make comparisons among comparable situations relating the manuals.
The unit rates for the standard, expressed in wh/sf, are: 0.236 for "Clark"; 0.131
for "Berger"; 0.073 for "Dodge"; 0.075 for "Means"; and 0.067 for "Richardson".
Notice that, although each data point in a Manual may represent an average of
several collections, there are no established standard procedures, common to all the
Manuals, to calculate the productivity rates. Then, it is very common to fmd different
unit rates related to the same case, as it happened with the unit rates for the standard.
Some explanations are: certain Manuals are more conservative than others; some may
consider the management hours as part of the input, while others only take into
account the direct labor; etc. But, many times, the comparable values in two distinct
Manuals differ roughly by a constant. This is the typical situation in that the use of
conversion factors will improve the fit of data, as illustrated in Figure 3: the unit
rates and the conversion factors for walls non-stick coming from two distinct Manuals
(Berger and Means) are plotted; although there is a significant difference between the
unit rates proposed by them, there is a close agreement in relation to the conversion
factors.
The process of defming equations to estimate the conversion factors for each category
of fonns, as illustrated by Figure 4, follows the steps: for each "category of
fonnwork" one must list all the variables that potentially can affect the conversion
factors (CF); during a "preliminary individual evaluation" , each variable, one by one,
will be checked by means of "graphical analysis" (for example plotting the CF in
relation to the variable), "statistical analysis" (for example using individual ANOYA
and individual regression analysis), "personal evaluation" (taking into account past
experience and common sense), and "confidence on the data" (involving both the
number of available data points and the clearness of Manual's infonnation); the
remaining variables (named "potential variables") are now evaluated together, by
means of "graphs" and "statistical analysis", to take into account the eventually
present interactions effects; the variables in the fmal equation will be the ones with
good statistics, with significant impact over the CF being calculated, and the ones
that are considered causal variables.
Conversion factors for analysis 21
0.20 0
0 0
0 0
0 0
0 0
2 0.15 0 0 aJ
E 0
0
0
::i 0
''"
0.05
}+
+
+
+
10 15 20 0 Berger
height + Means
2.1 -
0
1.6 -
0
LL. 0 + 0
0 0 0 bJ
+ 0 0
0 0
1.1 - + 0 0
0 0
+ 0
0
+
0.6
10 15 20
height
Figure 3- Comparison between the infonnation from two Estimating Manuals (Berger
and Means) for walls non-stick: a)unit rates; b)conversion factors.
22 de Souza and Thomas
IIvlliiable vllriables
preliminary individual
evaluation
potencial variables
group evaluation
final equation
Regression Analysis
Regression Analysis
Regression Analysis
Regression Analysis
Regression AnalYSis
=
CF 1 + 0.15*gang - 0.16*(steel surface) + 0.106*(9'<h<=16') +
+ 0.187*(h>=17') +0.321*curved
The following example uses data collected in Central Pennsylvania (United States of
America) in 1995 from the construction of a big gymnasium (seating capacity:
16,500). Table 3 illustrates the necessary steps to transform the quantities, measured
for each item, into equivalent quantities of the standard condition. Notice that, to take
into account the different efforts involved in assemble and strip the forms, these parts
of the item being done are tracked separetedely and receive weights respectively of
0.85 and 0.15 (for example: 100 sf of assembled form represent 85 sf of the item's
job, while the same amount of stripped forms mean only 15 sf). Finally, Table 4
shows the calculation of the daily unit rates: the total equivalent quantities represent
the summation of the several items performed that day; the workhours are the total
hours related to the formwork as a whole (and not for each item); the daily unit rate,
then, being connected to the standard condition, represents a standard measurement
of productivity.
8 Conclusion
Traditional cost systems break the work in pieces (items) and require the
measurement of both the amount of work done and the workhours spent for each
piece. This report showed that conversion factors can be used in order to simplify the
labor measurement and to create a gauge for productivity calculation.
Based on data collected from estimating manuals five equations (one for each
category of form: CU, CNURec, CNURou, WU, WN#) were developed to allow the
transformation of amounts of any type of formwork into standard equivalent
quantities. Using these equations, it is only necessary to track the total workhours
spent with forms instead of observing the labor consumption for each item. The use
of standard quantities turns the unit rate into a standard productivity measurement,
what makes the comparison between measurements in different days and/or sites
possible.
Conversion factors for analysis 25
9 Table of conversions
10 References
1 Bukhart, A.F. (1994) Selecting a wall fonning system for your next job, in
Selecting and Using Wall Forms. Aberdeen, Louisiana, pp.18-53.
3 Adrian, J.J. (1975) Realistic calculations of costs for wall fonning systems.
Concrete Construction, June.
5 Backe, C. (1994) Wall fonns: selecting the best ganged system, in Selecting and
Using Wall Forms. Aberdeen, Louisiana, pp.54-58.
6 Thomas, H.R. and Kramer, D.F. (1987) The manual of construction productivity
measurement and performance evaluation. crr, Austin, 168p.
8 Hlibok, A.J. (1984) The 1984 Berger building & design cost file. Hicksville,
Building Cost File Inc., VoU, 479p.
9 Iavarone, R.C. (1987) 1988 Dodge unit cost data. New Jersey, McGraw-Hill,
338p.
Abstract
The Organization and Management of Construction: Shaping theory and practice (Volume Two).
Edited by D.A. Langford and A. Retik. Published in 1996 by E & FN Spon. ISBN 041922240 5.
28 de Souza and Thomas
Sommaire
Les couts de main d'oeuvre sont loin d'etre negligeables dans Ie
batiment. n est indispensable, pour gerer au mieux les ressources humaines,
de connnaitre les facteurs qui influencent les variations de productivire, et
dans quelle mesure.
De nombreux chercheurs ont tenre de developper des modeles de
variabilire de la productivire ([1], [2], [3], [4], [5]); cette tache s'avere
cependant ardue. Nombre d'activires du bil.timent - tel Ie coffrage - sont!res
couteuses en temps et en hommes, et on observe que les facteurs agissant sur
la productivire sont de nature operationnelle autant qu'environnementale.
La modelisation des facteurs ("Factor Model") developpee a la
Pennsylvania State University (PSU), aux Etats-Unis, circoncit ces facteurs
statistiquement. Ce papier a pour objectif de presenter Ie developpement
d'une modelisation applicable au coffrage en beton, uniquement ici pour Ie
coffrage des murs et des colonnes.
Cette recherche s'est ainsi deroulee: un manuel des procedures pour Ie
coffrage, moyen standard de recolte des donnees, a ere developpe a la PSU;
l'auteur a recueilli des donnees quotidiennement, sur Ie chantier d'un
gymnase d'une capacire de 16 500 places et situe dans l'enceinte du State
College Pensylvania, Etats-Unis, pendant une periode de 250 jours travailles;
les donnees de 5 autres projets [6] observant les memes procedures ont par
ailleurs ere utilisees dans la presente etude.
Apres la reunion de toutes les informations recueillies aupres des
sources citees precedemment, l'analyse statistique a fait apparaitre une
equation mathematique qui identifie les facteurs et leur influence sur la
productivire humaine.
Explanatory model for labour productivity 29
1 Introduction
The observation of a real process for a certain period of time allows the construction
of models that provide understanding: the explanation of what has happened and the
forecast of future events. Figure 1, based on Casti [7], illustrates this mechanism.
r-----, r----,
I
I I
I
I
I inputs
I
I
Inputs
-.! encoding
(explanation)
observed
laws procr.ss sample model
01 a
I
process
I
outputsi'
I
decoding
forecactin 9)
i'OlltplllS
I
I
I
L-~ '--~
Figure 1- The modeling relations.
The Factor Model [8], based on the crew level productivity, was developed in the
Pennsylvania State University (PSU). Graphically shown in Figure 2, the
development of the model assumes the existence of an "standard condition of work";
under this condition, the daily productivity will be the "ideal" (here one may assume
the existence of learning or not); variances in the work scope and/or in the work
environment make the productivity vary in relation to the ideal. The model relates
the actual daily productivity to the daily work features.
~
.£
o
t:
S WORICTYPE
a:I7~~
..
w
PHYSICAL ELf:MEHt'
g~ CONSTRUCTION METHOD
~ DESIGN REQUIREMEIiTS
UNrrSOFWORK
In this report the Factor Model approach is used in order to "explain" daily
productivity variability: detecting the factors that generate variation and their degree
of influence, based on nonnaI workdays (Figure 3).
disruptions/outliers
To reach these goals the report discusses the following issues: standardization of
productivity measurement; collection of daily infonnation; preliminary evaluation of
the factors; modelling; and final checks.
This paper adopts, as a tool to measure daily productivity, the daily unit rate [9],
defmed as the ratio between the inputs (labor workhours) and the output (work
quantities). In order to establish a standard measurement, it is necessary to have
standard measurements of both the inputs and the outputs.
The measurement of labor consumption (input) was done as prescribed by a PSU's
manual for data collection [10]. The main recommendations are: to track the
workhours spent by one crew, that "consists of the foreman and the gang members";
"hours of absenteeism are not counted"; support personnel are only take into account
when their work is devoted exclusively to the crew; the recorded workhours are the
paid hours . (excluding eventual "premium"). The quantities measurement
standardization relies on the following ideas (Figure 4): to recognize the parts
(subtasks) that constitute a task and to record quantities individually allocated; to add
these quantities accordingly to the relative demanded efforts (rules of credit); to
transfonn the quantities for each different task into equivalent amounts of the
standard task (conversion factors) and to add them to fmd the daily quantities of
standard work. The units of measurement are: workhours (wh) for the inputs, and
square feet (st) of fonnwork for the outputs; then, the unit rate will be expressed in
workhours per square foot (whist).
Explanatory model for labour productivity 31
quantities
r c
u 0
I n
e
s
of
c a
r c
e t
d 0
r
s
3 Daily information
The description of daily performance includes both the calculation of the unit rate
(expressed in terms of standardized inputs and outputs) and the description of present
factors that may influence productivity. The standard measurements of amounts of
labor (input) and work (outputs) were previously discussed in this report. In relation
to the "productivity influencing factors", some additional comments are: some of
them were included in the conversion factors' equations; the remaining ones may be
divided into quantitative and qualitative variables; for the qualitative ones it is
necessary only to detect its presence or absence; the quantitative ones demand a
quantification task; the number of factors to be tracked should be as big as possible,
under the researcher's point of view, but as low as necessary to diminish the
spending time for future practical use of the fmal model by contractors; previous
experience helps in defming what factors must be tracked; try to avoid factors that
present difficulties in being measured; as far as possible, use factors common to
former data collections; because this report deals with an explanatory (and not a
forecasting) model, it is possible to use daily features as factors, instead of
information necessarily extracted from plans (for example, one can use the number
of the floor in execution in a certain day instead of the building'S height).
32 de Souza and Thomas
This report uses databases collected accordingly to the procedures developed at the
PSU. Table 1 summarizes the main features of the available databases.
Once the infonnation about the available variables has been collected in the fonner
step, it is time now to check which ones are really important for the model's
development: different approaches were used for quantitative and qualitative
variables; the checks include the use of graphical and statistical tools (analysis of
Explanatory model for labour productivity 33
AVAILABLE VARIABLES
v-l Ir;:1====+
~ -//-
e.1)
c)
e.2)
o dJ
Table 2 summarizes the results for the qualitative variables. Some additional
comments are: in relation to the 95% confidence intervals, a "good" plot is that one
with no superposition between the ranges of variation for the conditions being
checked; "difficult access" is considered to happen whenever there is not only
elements easily approachable being formed; although the results for "elevation
change" and "bulkheads" are not so bad, there is an inconsistency between the data
and the expected performance: days with these factors present have a smaller unit
rate than days without.
Table 3 summarizes the results for the quantitative variables. Some additional
comments are: plotting the unit rate against the variables allows the visual detection
of the existence of a "trend" (possible flag for a relationship); in order to fit the
reality, the "density" of comers, elevation changes and bulkheads, separately, are
studied; "density" is defmed as the number of units of the factor (for example the
number of comers formed in that day) multiplied by 1000 and divided by the total
equivalent amount of form work job for the same day; "T1 +Tdp", the summation of
air temperature and temperature of the dew point at 1:00PM, is used to analyze the
effect of weather over the labor productivity.
5 Modelling
6 Final checks
Four different approaches are showed to check the model's equation: coefficient's
statistics; infonnal evaluation; effect on the standard deviation; omitting databases.
Coefficient's statistics
Table 4 presents the main statistics related to the coefficients of the model's factors;
they are significant.
Omitting databases
When developing a forecasting model, the last stage of the process is to confront its
predictions with new data coming from a database not used in the model's
development. Although this is not the case (this report is concerned with an
explanatory model), a similar approach will be used in order to check the confidence
one can credit on the model: "new" equations were developed accordingly to the
same process used to create the "model's" equation, but making use of all databases
except one; because there were six databases, it is possible to develop six new
equations based on the five remaining databases; the intercept and coefficients values
for the "model's" and the six "new" equations can be seen on Table 5.
Table 5- Intercept and coefficients values for the "model's" and the six "new"
equations.
constants
intercept difficult pour coord. box or pipe
model 0.0797 0.0299 0.0282 0.0342
new 1 0.0716 0.0341 0.0299 0.0387
new 2 0.0905 0.0192 0.0279 0.0346
new 3 0.0854 0.0256 0.0254 0.0325
new 4 0.0810 0.0303 0.0239 0.0347
new 5 0.0761 0.0346 0.0264 0.0272
new 6 0.D705 0.0430 0.0520 0.0405
In order to check the agreement among all the generated models, all the equations are
plotted together, as can be seen on Figure 7, for different working conditions. The
visual evaluation shows a good harmony among them: the points are close to each
other.
7 Conclusion
length of workday; bulkheads; accessibility; pour coordination; and crew size. The
Factor Model approach helped in create an equation that shows the factors to be
considered and quantifies their influence on the daily unit rate value: the ideal
productivity (standard condition of work) is 0.080 whlsf; "difficult" access represents
an increase of 0.030 whlsf; days with concrete "pour coordination" mean an
additional 0.028 whlsf; and extra 0.034 whlsf can be credit to days impacted by box
out or pipesleeve work. This kind of information can help the site management in
different ways: as baseline for performance evaluation; as source of information to
defme production goals; in defming strategies to make easy the "access" to the
elements (for example, to defme an advantageous forming sequence); in taking
decisions about having an special crew only for concrete pour; etc.
0.25
.. model ur
0.2
-+ new 1
.....
Q)
*new2
co
.... 0.15
:!:::! -B new 3
c:
:J ~new4
0.05
different conditions
Figure 7- Plot of the "model's" and the six "new" equations for different working
conditions.
38 de Souza and Thomas
8 Table of conversions
9 References
2 Thomas, H.R. and Sakarkan, A.S. (1994) Forecasting labor productivity using
the factor model. ASCE Constr. Engrg. and Management, Vol. 120, No. 1.
3 Sanders, S.R. and Thomas, H.R. (1991) Factors affecting masonry labor
productivity. ASCE Constr. Engrg. and Management, Vol. 117, No.4. pp.626-
644.
7 Casti, J.L. (1990) Searching for certainty: what scientists can know about the
future? W. Morrow, New York, 496p.
10 Thomas, H.R., Homer, R.M.W. and Smith, G.R. (1991) Procedures manual
for collecting productivity and related data of labor-intensive activities on
commercial construction projects: concrete formwork. PTI, State College, 63p.
OVERMANNING AND THE EFFECTS ON
LABOR EFFICIENCY
H. Randolph Thomas
Professor of Civil and Environmental Engineering,
Pennsylvania State University, University Park, Pennsylvania, USA
Todd M. Arnold
Graduate Assistant, Pennsylvania State University,
University Park, Pennsylvania, USA
SUMMARY
SOl\1MAIRE
INTRODUCTION
The Organization and Management of Construction: Shaping theory and practice (Volume Two).
Edited by D.A. Langford and A. Retik. Published in 1996 by E & FN Spon. ISBN 0419222405.
40 Thomas and Arnold
SURVEY INQUIRIES
The survey instrument requested the following infonnation about a specific project that
was accelerated or compressed:
• Project type
• Planned and actual number of electricians
• Estimated loss of efficiency caused by ovennanning
• Planned (budgeted) and actual workhours
• Estimated and actual schedule duration
In total, infonnation was provided on 129 projects. There were complete responses
for 110 projects. Table 1 summarizes the surveys according to the project type and
average planned maximum number of electricians. As can be seen, most projects
were industrial, commercial, or institutional. The average planned maximum number
of electricians ranges from 4 to 50. Comparatively few line projects were contributed.
Inside Projects:
Industrial 45 50
Commercial 26 40
Institutional 29 28
Communications I 4
Line Projects;
Transmission 1 9
Distribution 2 6
Substation I 10
Underground 0
Communications 5 43
For the data analyses, several parameters were calculated. The first is the percent
ovennanned which was calculated as follows:
Overmanning and the effects on labour efficiency 41
Percent Overmanned (%) = ( Actual Max. No. of Elec. -1.0) x 100 (1)
Planned Max. No. of Elec.
The total loss of labor efficiency relies on the actual workhours and the budgeted
or planned workhours. These values are used in equation 2.
Figure 1 shows the distribution of the total efficiency loss for all projects as a function
of the percent ovennanned. Using equation 2, an efficiency loss of 25 % means that
33 % more workhours were required than budgeted. As can be seen, the number of
workhours required can exceed the budgeted or planned workhours by a considerable
margin.
The relationship between the total loss of efficiency and the ratio of the actual
divided by the planned schedule duration was also investigated. From figure 2, this
relationship is unclear. However, it is obvious that few projects finish early or on
time. In the survey, 68 percent of all projects took more workdays than planned.
The survey requested the estimated percentage of the total labor overrun attributed to
providing additional manpower resources, i.e., ovennanning. The distribution of
percentage estimates is shown in figure 3. It is obvious that the consensus of opinion
of electrical contractors is that ovennanning causes considerable loss of efficiency.
The average estimate is 29 percent, but in many instances, the estimated percentage
is much higher.
The net loss of efficiency caused by ovennanning was calculated by mUltiplying
the total loss of efficiency from equation 2 times the estimated percentage of the total
labor overrun attributed to ovennanning. The net efficiency loss is shown in equation
3.
Total Elf. Loss x Est. % From Overmanning (3)
Net Elf. Loss (%)
100
Figure 4 shows the relationship between the net loss of efficiency and the percent
ovennanned. The general trend is that as the percent ovennanned increases, the net
loss of efficiency also increases.
The net loss of efficiency from ovennanning was also investigated for other
relationships. No correlation was evident between the net loss of efficiency and the
42 Thomas and Arnold
planned size of the work force or the planned duration. Thus, from the survey, it
cannot be said that larger or longer duration projects have greater efficiency losses.
This observation may be different if there were more larger projects in the database.
Figure 5 shows that half of the database is from projects where the planned maximum
number of electricians was 20 or less.
The net loss of efficiency by project type was also investigated for indoor
projects. A linear regression equation was calculated for all indoor projects and
industrial, commercial, and institutional projects. These equations are shown in figure
6. As can be seen, when the percent overmanned is 25 percent or less, there is
minimal difference between the net loss of efficiency as a function of project type.
Because there were insufficient line projects to examine by type, a linear
regression equation was calculated for all line projects. Figure 7 compares the indoor
and line projects. There appears to be minimal difference between these two groups.
To validate the results of the survey, losses of efficiency were calculated for each
project type at 50 percent overmanned (see figures 6 and 7), and the results were
compared to the summary curves from the literature review. From the literature
review, the range of efficiency loss at 50 percent overmanned for small and large
projects is between 8 and 15 percent. As shown in figure 8, the results of the survey
are within this range.
SYNOPSIS
The results of the survey are generally consistent with the published literature on net
loss of efficiency caused by overmanning (homas et al. 1994). The data also show
that efficiency losses as a function of project type can vary. Table 2 summarizes the
difference between project types by showing relative increases and decreases in
efficiency loss. The category representing the analysis of all indoor projects is used
as the base for the indoor projects. The relative differences in table 2, called
efficiency loss multipliers, show that institutional projects are affected least and
industrial projects are affected the most. Further, the efficiency losses reported from
the survey showed no correlation to the planned size of the work force or planned
schedule duration.
CAUSES
The survey asked the respondents to indicate the principle cause of the acceleration.
The responses to this open-ended question are summarized in table 3. As can be seen,
the highest frequency of causes are related to design changes, change orders, and
scope alterations. Another category offrequent responses covers scheduling, planning,
and coordination. These factors may be as a result of problems with the design or the
inability of the prime contractor to adequately manage the project.
Overmanning and the effects on labour efficiency 43
CONCLUSIONS
The survey confmns in numerical tenns what has been generally known in the
construction industry, that is, staffmg a project with more craftsmen than was planned
leads to losses in labor productivity. This infonnation should be of value to both
contractor and owner in negotiating an equitable adjustment to the contract sum when
schedule acceleration requires the contractor to hire more craftsmen than planned.
REFERENCES
Indoor:
All 11.70 1.00
Industrial 12.25 1.05
Commercial 10.08 0.92
Institutional 9.65 0.82
Line:
All 10.80
>-
u
.~ 80
.~ 70
°° °
c......
~ 60
° °° ° °
50
c......
0 ° °° °
en 40 ~
00<ID
§
°8 00
0
0
0 10 20 30 40 50 60 70 80 90
Percent Overmann~d (%l
Figure 1. Total loss 0' erriciency vs. ~ercent overmanned.
~
- 80 o
>- o o
g 70 o
.~ 60 o 0 o
::: 50
w 40
c......
0 30
en
en 20
o
--.l 10
~ 0
o I
I-- 0 3 4 2
Actual Duration / Planned Duration
Figure 2. Total loss 0' erriciency vs. actual dur'ation I planned duration,
46 Thomas and Arnold
30
(!l
Q)
(J)
c
o
0.20
(J)
Q)
a::::
'"-
o
'- 10
Q)
..0
E
::J
20
0.0 0.1 0.2 0.3 0.4 0.5 0.6 OJ
Estimated Loss from o'Lermanning
Figure 3. Distribution or estimated proportion or total erriciency 105S attributed to overmanning.
o
>-40
() o o
C
Q)
o
·u 30
'"- o
'"- o
W
20 o o
'"- o
o
~ 10 o
o
---.J
a; a o
2
a 10 20 30 40 50 60 70 80 90
Percent Overman ned (%)
Figure 4. Net loss or err;ciency vs. percent overmanned.
Overmanning and the effects on labour efficiency 47
>-
()
c
~ 1.00
0-
(l)
'-
l.J....
(l)
>
...... 0.50
co
(l)
a::
(l)
>
......
co
:J 0.00
E
:J
U
o 20 406080100120140160180200
Planned Maximum Manning Level. Mp
Figure 5. Distribution of planned maximum manning level. Mp.
~25
>-
()
c(l) 20
.-
()
c.-
c.-
IS
w
' - 10
0
.(f)
(f)
0
5
---l
...... 0
(l)
z: 100
0 50
Percent Overmanned (%1
Figure 6. Net loss of efficiency vs. percent overmanned.
48 Thomas and Arnold
s.Q
>-20
u
c /
/ Indoor
Q) /
/
u /
/
/
/
'--
'--
w
'--
lO /
/
0 /
/
/
/
(J)
(J)
0
---l
...... 0
Q)
z: 50 laO
a
Percent Overmann~d (%1
Figure T. Net loss of efficiency vS. percent overmanned.
s.Q r-
l5 -
>-
u .---
c
Q) r-
r- .---
u lO - .---
.---
'--
'-- ,.--
w
'--
0
(J)
5 -
(J)
0
---l
...... --l L-J - '--
Q) 0 - . '-- l-
I I
z: ["du~trial In't1t~lional Small large
Commercial All Indoor
Indoor Line All Proj. Literature
Work Type-
Figure 8. Net loss of efficiency @ 50:: overmanned.
STEEL FRAMING CREW
PERFORMANCE AND VARIATION
Gary R. Smith and Yu-Bin Lin
Department of Civil and Environmental Engineering,
Pennsylvania State University, University Park, Pennsylvania, USA
Abstract
Traditional forecasting models, reported for labor-intensive productivity, have not
provided much insight into structural steel productivity and the factors affecting steel
construction crews. The factor model has introduced many new facets into evaluating
crew level performance in addition to providing a reasonably accurate model. Accurate
forecasts for crew-level performance can also be an important element of project control.
This paper examines those factors, which were identified through project based research,
that contribute to steel crew productivity variation. Understanding this variation is the key
to understanding process control and development of productivity improvement
procedures.
Data was compiled from nine steel frame construction projects. Each work day was
classified according to those factors and disruptions that had an impact on the crew that
day. When combined, 235 days of data were available for analysis. This data was
evaluated for the purpose of determining the most significant factors and their overall
influence on performance. A model of the crew performance was developed from the
significant factors. Process control chart concepts were reviewed to identify whether the
variability in the crew performance could have been identified in a manner that would
have permitted corrective action in a timely fashion. Although interpretation of the results
are somewhat limited, the combination of process control charts with forecasts may
provide a method to better understand project performance variation causes and provide
an opportunity to better control the field process.
The Organization and Management of Construction: Shaping theory and practice (Volume Two).
Edited by D.A. Langford and A. Retik. Published in 1996 by E & FN Span. ISBN 0419222405.
50 Smith and Yu-Bin Lin
Sommaire
Les modeles traditionnels de prevision des productivires couteuses en
heures de travail n'ont guere apporre jusqu'ici d'eclairage sur la productivite
structurelle de l'acier ni sur les facteurs affectant les equipes de la
construction acier. La modelisation des facteurs, qui s'avere etre relativement
precise, a mis en lumiere nombre de nouvelles facettes de l'evaluation du
niveau des performances des equipes. Des previsions precises du niveau de
performances des equipes peuvent etre un element important du controle de
projet. Le present papier examine les facteurs, identifies au cours d'un projet
de recherche, qui affectent les variations de la productivite des equipes acier.
Com prendre ces variations revient a com prendre Ie controle des processus et
les procedures d'amelioration du developpement de la productivite.
Les donnees ont He recueillies sur 9 chantiers de construction de
charpentes acier. Chaque journee de travail a ere classee selon ces facteurs et
selon les evenements qui sont venus deranger l'equipe ce jour-lao Une fois
compilees, ces donnees representaient 235 jours de donnees a analyser. Elles
l'ont ete dans Ie but de determiner les facteurs les plus importants et leur
influence sur les performances des equipes. Le concept des graphiques de
controle des processus a ere revu pour tenter d'identifier si la variabilite des
performances des equipes aurait pu etre identifiee d'une maniere qui aurait
permis une action correctrice a temps. Bien que l'interpretation des resultats
soit quelque peu limitee, la combinaison des graphiques de controle des
processus et des previsions pourrait s'averer un bon outil pour un meilleur
controle des processus sur Ie terrain.
Steel framing crew performance 51
1 Introduction
Developing accurate estimates is important during the planning and execution phases of
all construction projects. The purpose of this paper is to introduce quantified factors that
significantly affect steel erection productivity on the basis of field data. The factor
analysis is viewed as the first step toward developing accurate estimates. Process control
charts are employed to demonstrate the variability inherent in the process.
A key to effective forecasting is the development of an accurate model. Multivariate
factor models have been designed to respond to a range of factors [1]. Many factors have
been observed which influence productivity like temperature and humidity [2] and crew
size [3]. Sanders quantified significant factors for masonry construction [4]. Pace
demonstrated the model was a plausible alternative to conventional forecasting techniques
[5]. Sakarcan tested the model on international projects and found it to be reliable [6].
Detailed development of the model has been limited to masonry productivity.
1.3 Modeling
Project-related factors, weather zones, and crew sizes were evaluated using analysis of
variance techniques to determine the statistical significance of these factors prior to
including them in the model. After deciding which factors could be included in the
regression, the coefficients for the variables can be obtained though the regression
process. The effects of disruptions are addressed through an impact comparison to the
average non-disrupted productivity.
2 PROJECT FACTORS
Project factors are specific construction requirements, dictated by the design of the
project or construction methods, which can be identified from the plans and
specifications. In this study, project-related factors were classified as: Work Types,
Physical Elements, Design Details, and Construction Methods. Workdays are
classified according to the work performed that day.
• Beam & Girder, Multistory - The structure has multiple floors with nearly identical
layouts. Floor loads are transmitted directly from the floor slabs to the steel beams
and girders.
Steel framing crew performance 53
• Beam & Joist, Multistory - The structure has multiple floors with nearly identical
layouts and floor loads are transmitted through web steel joists to beams and girders .
• Truss or Sloped Roof - Roof structure is not flat but is sloped. The roof system
wi11likely consist of roof purlins and metal deck rather than a concrete deck.
An analysis of variance, with the data grouped by Work Type, indicates that there is a
statistically significant difference between the Work Types (F-ratio 12.527 and
Significance Level of 0.000). Two of the three work classes have relatively small
samples which were obtained from a single project and bias the response.
The analysis of variance indicates a significant difference between these two factors (F-
ratio 18.053, Significance Level 0.000). This result is highly correlated to Work
Type.
54 Smith and Yu-Bin Lin
The mean values obtained from this data classification are provided in Table 5.
Analysis of variance indicates there is a statistical difference between these group
means (F-ratio 12.968 and Significance Level 0.000).
3 OTHER FACTORS
4 MODEL DEVELOPMENT
A stepwise regression analysis was used to determine the order of selection and which
variables would be selected for inclusion in the model. The stepwise model uses a
minimum F-value of 1.5 as the criteria to include or remove a factor from the model.
Table 7 summarizes the factor coefficients for the six variables included in the model.
The number in parentheses for the stepwise model indicates the order in which the
variables entered the model. The standard conditions of the model are:
5 DISRUPTION ANALYSIS
Table 8 summarizes the classifications of disruptions and the mean productivity value
determined for each set of data. Due to the small data sets for each noted disruption, the
results appear to be somewhat erratic. It would be expected that a disruption in
production would result in worsening productivity. In some cases the index shown here
would suggest improved productivity. The disruption index is the mean undisrupted
productivity divided by the mean disrupted productivity.
While control charts are quite common in practice for quality control applications, it
was felt that they may provide a more relative measure for understanding project
productivity and variation. For this evaluation, the project with the most consistent
daily work output was selected as the basis for the mean and standard deviation. This
procedure provided more restrictive upper and lower control limits.
Figure 1 is representative of many projects that have only a few incidents that
significantly disrupt production. The average productivity for this project was lower
than the control chart mean, including the disrupted days. A large proportion of the
project data is noted as disrupted. The field notes indicate that this crew had many
tool and material problems, but the data plot would suggest that the crew compensated
for these problems and maintained a degree of control. Figure 2 illustrates a project
that was overwhelmed by disruptions. However, the project did have a series of days,
late in the project, that fall within the control region, which suggests that the project
had the potential to work within the control limits.
Superficially, the control charts can make average projects look fairly good.
Current upper and lower control limits range from 0.62 mh/pc to 3.19 mh/pc. This
wide range of "normal production" may cover a range that is too large for control
purposes. At this time much of the variability within this region is felt to be related to
the process itself and not necessarily to external factors considered by the models.
Whether the control charts can be useful for project control purposes is still
questionable because of the large variations permitted within the upper action limits.
DAIL Y PRODUCTIVITY
PROJECT 6
9 o Disruption Noted
~
.l 8 Within Limits
c:= ,
~
> 5
u
~ 4
·0
UCL~3.190
- 3
0
CL
2 MU~1.904
LCL~0.6176
iJ
n 10 15 20 25 ItJorkday
DAIL Y PRODUCTIVITY
PROJECT 3
10
u
c-- 9
8
7
> 6
U 5
::J
-0
o 4
ct . 3 UCL=3.190
2 MU=1.904
LCL=0.6176
o
o 10 20 30 40
Workday
6 SUMMARY
The control charts show there is a great amount of fluctuation within "normal data"
which is not measured by the factors currently evaluated in the factor model. The
factor model and control charts demonstrate the difficulty of modeling performance
from field data. Large amounts of variation remain to be explained by either model.
However, the combination of techniques provides useful insight into improvements
needed in recording and measuring productivity at the project level for developing
forecasting tools.
7 REFERENCES
2 Smith, G.R. and S. Kilroy, Operations Impact From Temperature and Humidity,
Proceedings of the Canadian Society for Civil Engineers 1994 Annual Meeting,
Winnipeg, Manitoba, Canada
Steel framing crew performance 59
Abstract
This report presents the results of an investigation into the nature, length and cost of
delays, that occurred on thirty (30) building projects in Trinidad and Tobago.
This paper first discusses the circumstances that give rise to delays, the
classification of these according to responsibility and the effects they have on the
project cost and schedule. The data are presented, analysed, and conclusions drawn.
Sommaire
Ce travail present les resultats d'une recherche sur la nature duree et coilt des delais qui
se sont arrivee en trent (30) projets de construction a Trinite et Tobago. Ce travail
debatte premierement les circumstances qui donnent naissance aces delais, classifie
ceux-ci, selon la responsabilite et analyse les effets de ceux-ci sur Ie coilt et Ie progres
de chaque projet. Les donnees sont presentees, analysees et conclusions sont obtenues
1. Introduction
When a piece of work is scheduled to be carried out on a particular day and for some
reason cannot be completed, a delay is said to have occurred. This may be of little
consequence, unless it affects subsequent work when it may become significant in
terms of both its planning and its financial implications. Significant delays that occur
during a construction project will either extend its duration or increase its cost or both.
In addition, if completion is delayed the client may also lose out financially by not
having the facility (and its potential income) available when wanted, and the contractor
may lose out by not having his resources released to take on other work.
Unfortunately, there are all too many factors that can cause delays to construction
work, from those inherent in the technology and its management, to those resulting
from the physical, social and financial environment. Because there are often financial
The Organization and Management of Construction: Shaping theory and practice (Volume Two).
Edited by D.A. Langford and A. Retik. Published in 1996 by E & FN Spon. ISBN 0 419 22240 5.
Analysis of construction delays 61
implications to delays, the parties involved are normally interested in determining their
causes and allocating responsibility. However, it is rarely easy to determine a unique
cause, or to allocate responsibility and this, naturally, leads to disputes between the
parties involved.
An assessment of delays should try to determine as many of the following factors
as possible, as these are inevitably the focus of disputes:
(a) what factor or factors caused the delay,
(b) who was responsible,
(c) how long was the delay attributable to anyone factor
(d) what extra costs were incurred as a result of a delay.
These are the factors that have been concentrated on here.
The standard forms of building contracts do not seem to be particularly well
designed for dealing with delays. As a result delays often lead to disputes, which can
easily lead to litigation aimed at trying to establish legal responsibility and allocate
additional costs. Because litigation is itself such an expensive and long winded
process, it is best avoided. If it is possible to identify the main causes of significant
delays then it may be possible to introduce contractual or policy measures which could
help them be avoided in future.
In order to investigate the structure of delays, their causes and the costs
associated with them, a survey was undertaken into experiences on a number of
construction projects (30) in Trinidad & Tobago over the period from 1979 - 1992. In
all cases, the projects were let by a client, used a design consultant, employed some
form of site supervision and were built by general and specialist contractors selected by
conventional tender methods. Taking a year that had statistics fairly typical of the
period, construction in Trinidad and Tobago for the year 1990 accounted for 8.8% of
the Gross Domestic Product (current prices) and for approximately 11% of the
employed labour force [6][7].
financial complexion. Because every project will have a different set of financial
implications associated with late delivery, little could be learned from attempting to
generalise from a few specifics. As a result, this investigation focuses on the
implications of delays on direct costs during the construction phase of projects.
As a result, because delays are both disruptive and expensive, they merit close
scrutiny.
Any analysis is complicated by details, and when people are involved, details
proliferate. As an example of the sort of complications that can arise, the following
quotation is apposite: " ... suppose the owner failed to supply certain materials on time.
At the same time, the workers who would have installed the materials were on strike.
The contractor cannot claim damages for work that would not have been accomplished
had the owner-caused delay not occurred. He would, however, be entitled to a time
extension for the period of the strike unless it can be proved that the strike was due to
his own actions. This is an example of concurrent compensable and non-compensable
delays. The result is a time extension, but no damages for the contractor". [4]
3.Causes of Delays
(iii) Weather - when weather becomes unusually severe and surpasses the normal
(i.e. average conditions for an area over the previous ten years based on
meteorological data) for that particular locality during a specific season of the
year, it becomes a factor excusing delay.
4. Effects of Delays
A delay tends to act like a virus - very slowly, but with far reaching effects. Like the
symptoms of a virus, there are symptoms which are indicative of a situation developing
which may lead to a delay, they are:
(a) a general slowing down of the job,
(b) inefficient use of the weather, i.e. not using dry weather effectively,
(c) improper sequencing of activities, leading to work stoppages on some tasks
The increased cost of accelerating a job must be carefully considered by both the
client and contractor before the decision is taken. The contractor may favour
acceleration of the job at his own expense if he feels that he may be held responsible
for the delay and:
(i) the liquidated damages are more costly than acceleration,
(ii) certain operations are heading for an unfavourable time of year,
(iii) the same men and equipment are needed on another job,
64 Lewis and Ather/ey
The client may favour acceleration of the job at his own expense if he feels that he
is responsible for the delays and:
(i) he will have to pay penalty costs to the contractor for extending the period,
(ii) the original completion date has special significance,
(iii) the project will suffer a loss of profits greater than the cost of acceleration
In some cases, in the interests of goodwill, and where both parties perceive it to
be to their benefit, the costs of acceleration may be shared between owner and
contractor. It is also possible for delays to have a positive side effect, as when delays
are apparently inescapable, and the effects are sufficiently costly, the parties to the
contract may be inspired to seek new and innovative means of avoiding them. The
solutions that evolve may enable future problems to be avoided.
The worst effect of delays to a construction project is the termination of the
contract by either party. It is normally a last resort action taken by an owner, who
terminates the contract for excessive non-excusable delays. Any such termination must
take place within the legal framework of the contract.
Table 1 lists the clients, the total cost of the contract, the total number, the total
cost and the total length of delays on each contract. All costs and values, are quoted in
Trinidad and Tobago dollars (approximately TT$6 =US$I).
The figures show that on contracts worth $56,626,485, 95 significant delays
occurred, the delays cost $4,561,963 and involved 424 lost weeks of work. The cost
of delays represents approximately 8% of the overall cost of the contracts. The total
cost shown is the cost of the particular contract involved, not of the entire project, for
example, the Hall of Justice (project #21) had an overall cost of over TT$400 million,
while the painting contract reported here was worth TT$1.4 million. All these projects
were professionally designed and supervised.
Table 2 gives a more detailed breakdown of the 95 specific delays that were
reported on the 30 projects. Briefly summarising the data in Table 2, 57 of the delays
were deemed excusable and compensable, and these delays accounted for $4,333,972
of extra cost and 290 extra weeks of work. The delays which were deemed to be non-
compensable numbered 38, and these accounted for $227,991 of extra cost and 132
weeks of extra work.
Included amongst the excusable/compensable figures are two items recorded as
"Claims for loss and expense". These account for $580,000 of extra cost and no extra
time. These were claims put in by the contractors for extra payments against increased
overheads and loss of other work, which were caused by their being delayed on a job
(for reasons deemed excusable/compensable), but not having claimed this
compensation against any other specific delay.
A degree of consistency was achieved in the analysis because in most cases the
description of the details and the nature of the delay were agreed between the
respondentsand the conductor of the survey.
66 Lewis and Atherley
Project/Client
-
TABLE 1 A n allysIS
. 0 f P roJects
Total Cost Total Total Cost Total
($) No. of of Delays Length
Delays ($) of Delay
(wks)
1. Housin1! Development 8,600,000 2 250,000 48
2. Housing Development 8,400,000 2 210,000 36
3. Bus Terminal 7,000,000 5 210,000 48
4. *M.o.W. Drainage Division 35,000 1 2
5. *U.W.I. Inflammable Stores 263,647 3 3
6. *U.w.I. Environmental Lab. 488,782 3 15,836 13
7. *U.W.I. Fluids Lab. 412,734 4 12,000 12
8. *D.W.I. Offices and Classrooms 1,330,716 4 259,724 4
9. *D.W.I. Electrical and Electronic Lab 948,133 5 82,767 13
10. Ghany Site 21,000 2 12,700 4
11. Ishmael Khan 63,000 2 16,000 8
12. Trinidad Cement Limited 63,000 3 8,000 4
13. National Petroleum Ltd. 5,800 1 2.5
14. Print Masters 29,440 1 4
15. Associated Bnmds 12,000 1 3
16. *T.S.T.T. 29,000 1 5
17. *NIHERST 46,000 1 1,285 2
18. Government Health Center 23,530 1 4.5
19. *U.W.I. Offices and Classrooms 2 12,628,046 5 278,591 16
20. Colsort Mall 450,000 6 190,000 14
21. Hall of Justice 1,400,000 5 1,060,000 29
22. Farrell House 150,000 7 75,000 28
23. *U.w.I. Hi1!h Volta1!e Lab. 878,810 8 465,000 43
24. *D.W.I. Food Technolo~ Lab. 3,909,682 7 845,012 36
25. Scotia Bank Not available 4 8
26. Free Zone 1,600,000 2 4
27. Bank of Commerce 2,300,000 2 4
28. *TELCO Head Office 4,800,000 3 500,000 16
29. Hand Arnold 580,000 2 50,000 6
30. *D.W.I. FoodProcessin~Lab. 158,165 2 20,048 4
Totals 56,626,485 95 4,561,963 424
.. ..
*M.o. W. - Ministry of Works, Government of Tnmdad & Tobago
* U. W.1. - University of the west Indies, St. Augustine Campus
*T.S.T.T.- Telecommunications Services of Trinidad and Tobago Limited
*NIHERST - National Institute of Higher Education (Research Science & Technology)
'TELCO - Telephone Company
Analysis of construction delays 67
TABLE 2 (Continued)
Project Nature of Delay Type Cost Length
No. * ($) (wks)
20 Errors in plans & specs. E/C 12,400 1
Ambiguities in plans and specs. E/C 14,600 1
Omissions in plans & specs. E/C 23,700 2
Strike by General Contractor E/C 10,000 4
Additional work E/C 102,300 4
Redo ftnished work NE 27,000 2
21. Ambiguities in plans & specs. E/C 106,000 2
Omissions in plans & specs. E/C 170,000 3.5
Day works E/C 200,000 4.5
Extra painting/variations E/C 500,000 17
Redo ftnished work NE 84,000 2
22. Heavy rains EtNC 1,000 3
Omissions in plans & specs. E/C 4,000 2
Change in sequence by contractor NE 4,000 2
Procurement failures by contractor NE 3,000 2
Strike by main contractor E/C 2,600 8
Redo work damaged by strike E/C 10,000 4
Additional work by client E/C 50,400 7
23. Errors in plans & specs. E/C 20,000 4
Ambiguities in plans & specs E/C 5,000 3
Omissions in plans & specs. E/C 100,000 7
Procurement failures by contractor NE ** 4
Procurement failures by contractor NE ** 4
Additional work by client E/C 260,000 20
Late shop drawing approval by consultant EtC ** 1
aaim for loss & expense E/C 80,000
24. Errors in plans & specs. E/C 17,750 4
Ambiguities in plans & specs. EtC 15,000 4
Omissions in plans & specs. EtC 31,948 2
Heavy rains no work EtNC ** 4
Procurement failures by contractor NE ** 4
Additional work E/C 280,314 18
aairns for loss & expense EtC 500,000
25. Poor means of sequencing by contractor NE 2
Procurement failures by contractor NE 2
Procurement failure by subcontractor NE 3
Poor scheduling of work by contractor NE 1
26. Procurement failures by contractor NE
Lack of manDOwer NE 4
27. Poor work sequencing by contractor NE 2
Lack of space at site meetings ? 2
28. Slow change in project brief requirements E/C 4
Poor work sequencing by contractor NE ** 6
Additional work by client E/C 500,000 6
29. Poor work sequencing by Contractor NE 6,200 3
Additional work E/C 43,800 3
30. Errors in plans & specs. EtC 2,200 2
Additional work bv client E/C 17,848 2
• EtC =Excusable Compensable; EINC =Excusable Non-Compensable; NE =Non-Excusable
** Difficult to quantify
Analysis of construction delays 69
7. Discussion of Results
During the interviews with those involved, it was felt that the projects analysed here
were not untypical of the projects being constructed in Trinidad and Tobago at that
time, in other words, they were neither worse nor better than average in the number of
delays that they suffered.
Although each case study represented a 'project' to the company concerned, they
did not all represent complete projects to the clients involved, e.g. the painting contract
for the Halls of Justice was a project to the contractor, but only a very small element of
the total project to the client. This was not expected to make any difference to the
conduct of the work either by the contractor or by the client or his representative, or to
affect the results of this survey.
It is clear that the majority of the delays which were detailed fell into the category
'compensable excusable'. This bias almost certainly resulted from the fact that the
contractors would have been much more aware of the need to fully document delays
which they felt they could claim compensation for. Equally, the consultants would
have been aware of the contractor's intention to claim and would also have recorded
relevant details.
The non-compensable delays are made up of the portion of the delays that were
claimed for but rejected, as well as the delays that were recorded in diaries and minutes
of meetings but not claimed for. In no cases did the client enforce the 'liquidated
damages' or penalty clauses which were in the contract documents, even though very
significant delays (over 40 weeks) were experienced on some of the contracts.
Where values have been given for non-excusable or non-compensable delays
these figures were either on record as claims or were derived from the actual costs
involved in redoing work, or in accelerating the work to get it back on schedule.
One overall pattern that did emerge was that main contractors suffer more delays,
and more costly delays than subcontractors. This may have simply been a scale related
fact i.e. the more work you do the more likely you are to experience problems (which
seems to be substantiated in the related finding that larger jobs tended to have more
delays than smaller ones), or it may have been to do with the timing of their
participation in the works. The main contractor is likely to be involved earlier in the life
of a project, and hence at a time when it is likely to be least fully finalised, and when
the site is least prepared - subcontractors tend to get involved later on when things have
settled down, and problems causing delays are less likely to arise.
The general economic climate during the period under study was one of recession
and high levels of unemployment, and this generally tended to keep industrial action to
a minimum. Only two projects were affected by strike action, and in both cases it was
the work of the subcontractor being delayed by a strike affecting the main contractor
that was recorded. As a result, in those two instances, what would otherwise have
been an excusable but non-compensable delay became compensable as the
subcontractor claimed against the main contractor.
By far the largest factor leading to delays was the client requiring changes or
additions to be made to the project. If the 'top ten' causes for delays (by additional cost
incurred) are listed (see tabulation below) it will be seen that the quality of the drawings
and specifications that the contractors' had to work with appeared to leave much to be
70 Lewis and Atherley
desired. When the omissions, ambiguities and errors (items 4,7 & 9) in these
documents are added to variations required by the consultants, they accounted for
claims amounting to $1,528,365 and for delays totaling 72.5 weeks.
The consultants who were interviewed indicated that this was not a fair reflection
of their performance or competence as most of the variations and the problems with
drawings and specifications arose because of late design changes that emanated from
the clients. They, the consultants, had to respond and make the desired changes, and it
was this which caused the delays and cost increases.
It should also be added that during recessionary times the process of decision
making on capital investments tends to slow down, as a result of this the period over
which the design process takes place tends to expand. In the projects examined, for
example, the design of project 19 (University buildings) took 5 years from conception
to tender. Given the rate of technological change, it is hardly surprising that the client
required changes to be made to the project definition between the time of the brief and
the tender and before the completion of the building when such time scales are
involved.
In addition to this, as Bromilow has noted "... Variations are needed to help the cost
steering process and to cope with new ideas, changes in technology and mistakes; they
are, contrary to the view of many, an inevitable part of the building process. "[I] We
are dealing with delays rather than variations, but in practice, they tend to be
interdependent. Delays are often a consequence of variations;
During recessionary times the pressure to meet cost targets increases, and this leads
clients to 'tinker' with their projects in order to try to effect savings. For example, on
this particular project, in the original design (carried out during the boom years) all
services were centrally controlled, there were not even light switches in the individual
rooms. With the onset of the recession before building got under way, increasing
awareness of the need to control energy costs led the client to demand a revision of the
design to allow lights to be switched off in each room. Such 'cost steering' variations
led to design changes, which led to delays. Although the effect of such tinkering may
be delays and extra costs in the short term, in the longer term they may well be cost
saving, and hence very cost effective.
8. References
1. Bromilow, F. J. (1969). Measurements and Scheduling of Construction Time
and Cost Performance in the Building Industry. Report of the Division of
Building Research Division. CIRlA: Melbourne.
Analysis of construction delays 71
Abstract
Substantial clients of construction with extensive development programmes invariably
employ a range of contracting organisations. Some clients, notably in the public sector,
may employ widely from an extensive panel of contractors, whereas others may adopt
an approach in which a single or limited number of contractors are engaged for the
completion of a programme, in a manner which has become known as partnering.
Notwithstanding the procurement approach adopted there is an ongoing necessity for
clients to have some means of objectively assessing the performance and reputation of
these contractors as a way of evaluating current activities and also influencing future
procurement directions.
Sommaire
Des clients importants de l'industrie de la Construction, ayant de vastes programmes de
developpement, emploient en general une gamme d'enterprises de sous-traitants.
Certains clients, du secteur public notamnent, peuvent employer a grande echelle a
partir d'un large panneau de sous-traitants, alors que d'autres, peuvent adopter une
approche dans laquelle un seul sous-traitant est engage, ou bien il est fait appel a un
The Organization and Management of Construction: Shaping theory and practice (Volume Two).
Edited by D.A. Langford and A. Retik. Published in 1996 by E & FN Span. ISBN 0 419 22240 5.
Client benchmarking of contractor performance 73
nombre limite de sous-traitants pour terminer un programme, ce qui s'est fait connaitre
sous l'appellation de partenariat. Bien qu'il s'agisse d'approvisionnement, ou demande
d'achat, les clients doivent, en permanence, etre en mesure d'6valuer objectivement
l'execution et 1a reputation de ces sous-traitants, de maniere Ii 6valuer les activites
courantes et aussi Ii influer sur les orientations de l'approvisionnement futuro
L'evaluation des performances a fait son apparition comme moyen par lequel des
participants Ii un processus industriel ou commerciel peuvent piloter les performances,
en se referant a une evidence verifiable Ii partir d'activites comparables, peut-etre
derivee d'un certain accord sur Ie partage mutuel de l'information. La presente
communication examine les fayons dont les employeurs importants de l'industrie de 1a
construction peuvent adopter ce processus en tant que partie integrante de leur prise de
decision d'approvisionnement et d'action, et comme moyen de rehausser les
performances du projet et sa fiabilite.
Mots cles: Evaluation des performances, sous-traitants, performances,
approvisionnement
1 Introduction
"the continuous process of measuring products, services, and practices against the
toughest competitors or those companies recognised as industry leaders"
Ajoint definition from Coopers and Lybrand and the CBI states:
"the process for comparing business practices and performance levels against other
companies"
74 8a/dry
"the process for comparing business and performance levels against others and
providing reassurance as to the validity of existing methods and costs or suggestions
for improvements as appropriate"
The tone and content of these definitions lean heavily towards supply side issues in
terms of references to competition, relative performance, and costs of production, with
an emphasis upon the ongoing continuity of the process. The operational relevance of
so much benchmarking activity may explain the alacrity with which the facilities
management industry has adopted this approach as a means of comparing and
evaluating a plethora of measurable performance indices (Varcoe [2]). However the
respective performance of organisations must extend beyond readily measurable
indicators of performance and present a profile of the totality of an organisation. France
[3] offers a quotation from Manton, an acknowledged expert in the benchmarking field,
who states "A company or industry .......... must focus not just on numerical
comparisons but on business vision, business strategy, management processes and
current best practice".
For a commercial client the process of benchmarking offers the opportunity for a
structured means of comparing and evaluating supplier characteristics as an aid to
developing a procurement strategy capable of delivering reliable and superior
performance. A well considered benchmarking process should allow a client to focus
upon those issues of supplier performance which are critical to the successful
accomplishment of client organisational objectives. For regular or prospective clients of
the construction industry a benchmarking mechanism allows for appropriate weightings
to be applied to contractor performance in terms of price competitiveness, programme
reliability, technical expertise, experience of building type, product quality, claims
awareness, etc., to reflect the significance of these issues for the project sponsors
primary business.
are realised, the selection of supply contractors having a profound influence upon
project performance and outcomes.
The factors which can be identified which will influence the process of contractor
selection by the project sponsor may be stated as:
industry. Codling [6] has identified how three distinct types of benchmarking have
evolved from mutual information sharing relationships:
• Best practice - the seeking out of the undisputed leader in a specific business
process which is critical to organisational success. Competitive forces may mean
that this approach often requires a partnership relationship to be developed with a
leading organisation in an alternative relevant industry to that occupied by the
benchmarking organisation.
It may be recognised from the above that the intensity of benchmarking activity
occurs within organisations which are part of a product or service supply chain, being
both providers and procurers of resources and key components. For an organisation
which is dominantly the end consumer of goods or services, such as the sponsor of
construction project services, the process requires adjustment and refinement to reflect
the external location of the client organisation, its limited direct access to market
intelligence, and its often infrequent and occasional participation in the procurement
process.
As has been noted the application of benchmarking techniques has been widely
adopted in process industries and., in particular, taken up with enthusiastic vigour by the
rapidly expanding facilities management industry which is largely building related in its
activities. Some particular difficulties do emerge however when applying the process to
a project based industry such as construction which do need to be overcome if optimal
benefits are to be derived. An opposing view to this is held by Karlof and Ostblom [7]
who propose that the project form of organisational activity is highly suited to the
application of benchmarking techniques as the formation of an optimal ad hoc team
with specialised qualifications offers flexibility and the ability to operate outside regular
channels without being hampered by organisational formalities. Nevertheless difficulties
do exist which to some degree distinguish construction from other industries and
include:
• very few projects are alike given the variety of locations, participants, and product
content
• projects are invariably conducted by teams of participants assembled for the
duration of the project only and which are broken up on completion
• the supply side of the industry is highly fragmented both in the number and diversity
of available organisations
• some project sponsors are regular and frequent commissioners of construction
services whilst others take part once-in-a-corporate-lifetime
Client benchmarking of contractor performance 77
• the highly competitive and commercial nature of construction activity does not
encourage either supply or purchasing organisations to be forthcoming with
information
• the data generated from construction activity may be complex and variable and
subject to differing interpretation
• the application of benchmarking in construction has only minority penetration to
date resulting in a lack of knowledge and enthusiasm for its potential and often
being limited to cost comparisons only
the ire and contempt of contractors and their trade associations. The conclusion of
Latham is that it would be appropriate for the DOE to develop the CMIS scheme as a
centralised national resource to assist clients and their advisers to determine contractor
competence against a range of performance criteria.
From a client's perspective this paper suggests the following essential elements of an
effective scheme for benchmarking contractor capability:
• Interactive - capable of presenting the client with choices and alternatives with
which the client may engage to customise a search process
• Regularly updated - able to illustrate the most current and meaningful information
of contractor performance and capability
made available to contractors to verify the factual data on record and update if
necessary, and, if deemed appropriate, to examine the performance values placed
against them by contnbuting clients. It is proposed that it would be fair and reasonable,
and probably necessary to promote contractor confidence, to allow contractors full
access to the data file held against them in order to secure feedback on past client views
on their performance, the specific identities of these clients being necessarily concealed.
Latham is of the view that the DOE CMIS scheme could provide the framework for a
central United Kingdom resource for public sector contracts based upon an official
registration of contractors. It is suggested in this paper that such a system would have
limited acceptance into the private sector as the DOE would be too strongly identified
with the government in its role as a major client of the industry. Furthermore the
reluctance of government to directly intervene in commercial relationships in the
construction industry, and the limited capability of the utilisation of such a scheme
without legislative authority, would effectively hamper its widespread acceptance and
participation.
5 Conclusion
Construction clients are seeking to improve their procurement and supplier selection
process to reduce project risk and create conditions for a greater certainty and quality
of contractor performance. This paper has descnbed how the disciplined process of
benchmarking may be adapted from the conventional inter-company supply side
comparator of process activity into a means for the reliable and objective assessment of
contractor competence. Notwithstanding the obstacles presented by the peculiarities of
the construction process, when compared to the manufacturing or service industries,
and the particular necessity of the development of a culture of co-operation, it is
proposed that an effective and workable system meeting certain delivery criteria is
desirable and achievable. The types of organisation which would be suitable to accept
the responsibility for managing such a service have been reviewed and appropriate
bodies proposed. The outcome of the establishment and successful operation of a
contractor petformance benchmarking system is predicted to be a direct positive aid to
client procurement experiences, and it is also speculated that improved contractor
performance may result from the competitive forces arising from participation in a
formalised comparative process.
6 References
4. Chicken, IC. (1994) Managing Risks and Decisions in Major Projects, Chapman
Hall, UK.
Client benchmarking of contractor performance 81
1 Labour productivity
1984 Berger Building & Design Cost File" [8]; "1988 Dodge
Unit Cost Data" [9];
Standards"[ll].
of productivity.
8 Conclusion
338p.
3 Daily information
equivalent amount of form work job for the same day; "T1 +
Tdp", the summation of
5 Modelling
as independent variables:
Coefficient's statistics
Omitting databases
for the "model's" and the six "new" equations can be seen
on Table 5.
7 Conclusion
SOl\1MAIRE
SYNOPSIS
schedule duration.
CAUSES
1 Introduction
Disrupted and interrupted days are set aside from the model
analysis data set to remove
2 PROJECT FACTORS
conventional manner .
• Trusses and Irregular Shaped Members Work involving roof
trusses, composite,
Physical Element
Truss/Irregular Shapes
3 OTHER FACTORS
4 MODEL DEVELOPMENT
Constant 3.45
Medium Temperature,
was felt that they may provide a more relative measure for
understanding project
daily work output was selected as the basis for the mean
and standard deviation. This
~ 8
.l
c:= ~
'" ,
>6
> 5
u 4 ~
·0
0 3
forecasting tools.
scrutiny.
At the same time, the workers who would have installed the
materials were on strike.
3.Causes of Delays
4. Effects of Delays
A delay tends to act like a virus very slowly, but with far
reaching effects. Like the
for the delay and: (i) the liquidated damages are more
costly than acceleration, (ii) certain operations are
heading for an unfavourable time of year, (iii) the same
men and equipment are needed on another job, 64 Lewis and
Ather/ey (iv) specialist trades/services may be delayed
and higher costs incurred. The client may favour
acceleration of the job at his own expense if he feels
that he is responsible for the delays and: (i) he will
have to pay penalty costs to the contractor for extending
the period, (ii) the original completion date has special
significance, (iii) the project will suffer a loss of
profits greater than the cost of acceleration In some
cases, in the interests of goodwill, and where both
parties perceive it to be to their benefit, the costs of
acceleration may be shared between owner and contractor.
It is also possible for delays to have a positive side
effect, as when delays are apparently inescapable, and the
effects are sufficiently costly, the parties to the
contract may be inspired to seek new and innovative means
of avoiding them. The solutions that evolve may enable
future problems to be avoided. The worst effect of delays
to a construction project is the termination of the
Claims can arise for many different reasons and between any
of the parties involved in
The data collected were for projects done between the years
1978 to 1992 inclusive.
other respondent.
of extra cost and 290 extra weeks of work. The delays which
were deemed to be non
fact i.e. the more work you do the more likely you are to
experience problems (which
involved.
1 Introduction
primary business.
include:
following characteristics:
1 Introduction
Organization factor
The safety factor has for the time being only value
K = Ka x Kv
i.e.
Kk = Kak x Kvk
Each of the four factors (Kk, KI, Ko and Ks) can be now
shown as a combination of
(altered) times
initial one.
if Tap1 Tas = Tae1 > 0,5 (0,5 is the time relating to day
rounding up) 188 Petrovic next we carry out the procedure
mentioned above on time Tae1. The time extended in such a
way is also subject to the influence of external
conditions.Tae1 is, therefore a new, lesser extension
Tae2. Then we pose the same question again: if Tap2 Tap1 =
Tae2 < 0,5 then tap = tap2 if Tap2 Tap1 = Tae2> 0,5 then
time Tae2 is treated in likewise manner to get extension
Tae3 etc. The procedure is repeated until! we reach a
state where the length of the extension is less than 0,5.
This is reached in tree steps at most. Use of Computer
Investigation is under way and a program for the
calculation of practical activity (Tap) has not been
completed as yet. The description that follows is done on
the ssumption that such a program is completed. THE
FIRST STEP is a preparation of termed calendar with
coeff.for the entire company. Several sorts of termed
calendare are constantly updated and extended once they are
fed into a computer in planning department of a company.
These could be calenders with monthly, quarterly or even
longe term weather forecasts with date from multi-annual
calendars, logistic factors related to a state zones, or
areas,details concerning general organization patterns or
organizations on the level of company departmens etc. Term
calenders serve the entire compeny and it is up to the
project manager to choose which of them he is going to
use, ie. monitor. Likewise, we can use a calendar of the
actual external conditions. This one is done
subsequently, ie after the occurrance of the actual
external conditions. It is nesessary for us to be able to
check by a subsequent calculation whether the time on a
site is utilized effectively. A subsequent schedule will
help us to determine through a systematic monitoring which
of the factors are the most prominent and to what degree.
The program is conceivaed in such a way that it is
sufficient to indicate the first and the last day of the
influence factor, whereupon the same value is automaticaly
added to all the days inbetween. SECOND STEP in the
calculation of the practical time is the preparation of the
time schedule (let's take a network for an example) with
initial times (standard or theoretical). The network plan
has an innovation in the node. Now the node has nine
instead of eight pieces of information. A field is added
in the centre of the node in which practical time is
displayed. Time planning using the Zagreb method 189 Es
Tas LS Simb. Tap TF EF FF LF Fig. 3 Network node
We can see that the initial plan ends on the 30th day, that
it has 5 columns and cry tical
c K a k 1 C K a ! 2 C K a k 1 C K a l 2 C K a k 1 B K a ! 2
B ! < o k 1 A K a ! 3 8 K a k 2 A K a ! 3 8 K a k 2 8 K a l
3 B K a k 3 A K a o 1 A K a k 3 A K a o 1 8 K a k ] A K a o
1 A K a k I . A K a o 2 8 K a k l . A K a o 2 A K a k l . A
1 < 0 0 2 A K a l 1 A K a s A K c i 1 A K a s A K a ! 1 C K
a s A ' o E F K a k 1 B K a t 2 B K a k 1 C K a t 2 A K a k
t C K a l ] A K a k 2 A K a t 3 B K a k 2 B K a t 3 B K a k
2 B K a l 3 C K a k 3 A K a o 1 A K a k 3 B K a o 1 A K a k
3 A K a o 1 A ! < o k t . A 1 < 0 0 2 A K a k l . A K a o 2
A K d < l . A K o . o 2 A K a ! 1 A K a s A K a l 1 C K a s
A K a t 1 C K a s B ' ~ G H K a k t A K a t 2 A K a k 1 C K
a t 2 A K a k 1 C K a t 2 A 1 J < a k 2 C K a ( 3 B K c i k
2 B K a t 3 B K a k 1 B K a ( 3 A K a k 3 A K o o 1 B K a k
3 C K a o 1 B K a l e 3 C K o o 1 B K a k l . A K a 0 2 A K
a l e L B K a o 2 A K a k l . C K a o ] A K a f 1 C K a s A
K a ! 1 C K a s B K o . ( 1 C K G l . s C i F i g . 6 A c t
i v i t y s e n s i t i v i t y c o e f f i c i e n t s D /
F S ~ M T W T F S v ; t « T W T F S ~ M T W T F S ~ t « T W
T F S ~ t « T W D / I \ 1 2 X L 5 6 7 8 9 r § 1 1 1 1 1 3 l
L 1 5 1 6 ~ 1 8 1 9 1 0 1 1 1 2 2 3 ' 4 2 5 2 6 2 7 2 8 2 9
3 0 ~ 2 J L " " ~ ~ ~ < 0 ~ ~ ; ; ; [ j . . . . . . . . . I
I ' < D t I D ~ a s ; ; ; c . . . . . . . . . . ' " ' ~ < <
0 0 1 8 r ; D / G r ; : ! z I I ' < D c . r ' " 0 0 < 0 0 0
0 0 < 0 0 0 c . 0 1 0 1 0 1 0 1 0 1 < n 0 1 . . . . . ~ c .
K Y K T b b V a V a b b ' / c b V / / K Y K 2 / . v : V ' /
~ K Y K J V ~ v . ' i V / / K Y K L / / / / / V / V K Y L 1
a a / ' a a a a a a V , a Q a a a a ' i a a a a a a ' / a a
a a a a r / . a a ' a K Y L 2 / / b c b b b b V b b b b b b
/ b b b b b b V / b b K Y L 3 c c : / . c : c : c : b b c V
, , c c / / ' / : ' / K Y O 1 a a ~ a a a a a a V a a a G .
a a V ; a a a a a a / / " 7 K Y O 2 b b V b b V ' / v : t /
K Y S a a V / a a b b b b V b b b b b b v : ' / b b V b b b
~ ! J E ~ ~ ~ ~ 1 I ~ I ~ f ' / ~ B r : ; I / E V I I v : I
I [ 7 I I . . . L V . . . ( A I 0 : , F V I ~ I I ' L I I !
, V I r / I ' I V f . A c ' / . i F 7 ; : : I T 1 ' , / v :
~ / ~ o r ) H i . . . ( ~ ~ , / . ! I ~ t ! i ~ 0 I ( / . ~
T . ~ = r / i F i g , 7 T e r m e d c a l e n d a r 194
Petrovic In this instance we shall go for the the maximum
extension of a day per a day of an activity.Accordingly,
the sensitivity coefficients relating to the activities are
as follows A = 0,80 B = 0,90 C = 1,00 We have
likewise decided that the project will be in progres
during Sept. Oct. 1995 somewhere in central Croatia.
Working hours are 8 hours a day, six days a week. The term
calendar with a gantogram of the initial network plan and
the obtained after the calculation Oh practical times
(double line) would look as Fig. 7 It is evident that due
to the external influeces the completition date has been
siginficantly extended. Seing how the times of individual
activities varies until they settled. Initial Tae1 Tae2
Tae3 Tae4 A 4 6 7 B = 2 3 C = 6 9 11 12 0 5 8
10 E = 7 11 13 14 F = 3 4 5 G 2 3 H 10 17 20 21
22 I 7 10 11 Fig.8 Extension of activities Wi can
conclude that longer activies are more likely to be
extended, thus by the addition of new days being sorted
under new factors, which further extend duration of the
activities. The said days are obtained in the computer by
recurring calculations using the following tables. A part
is shown here only, which will suffice for the procedure to
be comprehended. See Figure 9. C 1 b K k l 1 . 5 K l l
0 K k 2 0 K I 3 B l c 1 . 5 7 5 K k 3 0 K o l A l a 1 . 0 K
k 4 0 1 < 0 2 B i b 1 . 1 2 K l l A l a K s D / a 1 . 0 1 .
0 K k 1 0 K l 2 0 K k 2 0 1 < 1 3 B l c K k 3 0 K o l A l a
K k 4 0 1 < 0 2 0 K l 1 A l a K s B I b C l b K k l K l l 0
K k 2 K k 3 K k L K I I K k l K k 2 K k 3 K k L 1 < 1 1 0 1
< 1 3 B l c 0 K o l A l a 0 K o 2 B i b A l a K s B l a 0 1
< 1 2 0 0 K i l B l c 0 K o l A l a 0 K o 2 0 A l a K s B i
b F i g . 9 F a c t o r m u l t i p l i c a t i o n t a b l
e s C i a K k l K I 1 0 K k l 0 K I 2 0 K k 2 0 K I 3 B l c
K k 2 0 K l l B l c K k 3 0 K o l A l a K k 3 0 K o l A l a
0 K o 2 B i b K k L 1 < 0 2 B i b K k L 0 K I I A l a K s B
l a 1 < 1 1 A l a K s B / a K k l 0 K I 2 0 K k 2 0 K i l B
I b K k 3 0 1 < 0 1 A l a K k L 0 K o 2 0 K l l A l a K s B
I b 196 Petrovic The tables are made for each day and the
highest coefficient is the one by which the day is
multiplied (which is to say that in fact the coff.are added
up). Therefore the first day the hihgest result was KI2
(8 x c = 1,575), the second day K01 (8 x a = 1,12) and the
third (extended) Kk1 (C x b = 1,5). The final network
plan shown in the next diagram suggests that the
completition date is much longer, 55 days (the date with
standard times is 30 days), which seems to indicate that
the external influences should not be ignored. In this
instance the influence of bad logistic and organization
were even stronger than rain which tended to prevail at
the time lEGENOA: 7 2 11 19 7 33 ES ti EF ~ B I.
21 rE 11. 13 AK Tat TF 18 8 32 32 13 1.6 lS FF
LF 0 I. 7 ~ 7 6 19 I19 3 11. 21. 2 17 ~ 1.6 7
57 A 7 0 C 12 0 ~ F 5 0 ~ G 1 19 ----..... I
11 0 0 0 7 7 0 19 19 0 11. 1.3 19 1.6 e.6 u 57
7 5 17 11. C 1.6 ~ 0 I() 7 H 12 01== 1£ I()
11. 11. 0 1.6 Fig. 10 Final network plan Conclusion
When making a conclusion it should be kept on mind that the
study carried out within the project New Methods of
Planing is still in progress. The results reported here
have yet to Time planning using the Zagreb method 197
applied.
completition, etc.
Faculty Osijek.
pp 84.
2 Study methodology
award amount and the estimated tender value and (5) number
of bidders. Due to inflation, all prices have been
standardized to the same basis. 1995 was chosen
California, uSA
Abstract
Resume
de sa gestion de projets.
la gestion de projets.
1. Introduction
3.1 Benchmarking
4. Research Methodology
4.3 Variables
proven to be working.
I N
S T
Y J a s e l s k i s [ 2 5 ] c o n s t r u c t i o n R u s s
e l l [ 2 6 ] c o n s t r u c t i o n C I I [ 2 7 ] c o n s
t r u c t i o n H e r b s l e b [ 2 8 ] s o f t w a r e P e
a r c e [ 2 9 ] h i t e c h [ 3 0 ] m a n u f a c t u r i n
g I b b s [ 3 1 ] c o n s t r u c t i o n
I A
L E
S /
F A
T O
S p r o j e c t s u c c e s s p r o j e c t s c h e d u l e
p r o j e c t c o s t p r o j e c t i n p u t c h a r a c t
e r i s t i c s p r o j e c t f a i l u r e , n o n f a i l
u r e p r o j e c t c h a r a c t e r i s t i c s t r u s t
i n d i c a t o r c o s t i m p a c t p r o c e s s i m p r
o v e m e n t c o s t p r o d u c t i v i t y d u r a t i o
n q u a l i t y b u s i n e s s v a l u e t i m e c o s t q
u a l i t y p e r c e n t c o m p l e t e c h a n g e c o s
t b u d g e t p r o d u c t i v i t y 8 P M B O K c r i t e
r i a S p t o j e c t l i / e c y c l e p h a s e s s c h e
d u l e , c o s t a n d q u a l i f J ' c u s t o m e r s a
t i s J a c t i i J n c R O H f t . P M . f J r a c t i c e
s
L O
Y q u a n t i t a t i v e m o d e l s t a t i s t i c a l l
y c o r r e l a t e p e r f o r m a n c e a n d p r o j e c
t i n p u t c h a r a c t e r i s t i c s s t a t i s t i c
a l a n a l y s i s : n u m e r i c a l : s t u d e n t t t
e s t q u a l i t a t i v e : c h i s q u a r e t e s t r e
g r e s s i o n a n a l y s i s b e n c h m a r k c o s t i
m p a c t s t a t i s t i c a l a n a l y s i s e m p i r i
c a l m e t h o d s m i n i c a s e s t u d i e s 1 t o 7 L
i k e r t s c a l e c h i s q u a r e t e s t c o r r e l a
t i o n a n a l y s i s l i n e a r r e g r e s s i o n m o
d e l s t u d e n t ' s t t e s t c o r r e l a t i o n a n
a l y s i s r e g r e s s i o n a n a l y s i s " d e v e w
p . q u a t t t i t a t i v e m o d e l 1 t o 5 L i k e r t
s c a l e b e n c h m a r k P M l e v e l
O
N
T R
I B
T I
N p r o j e c t m a n a g e r s c a n p r e d i c t t h e i
r c h a n c e s o f a c h i e v i n g s u c c e s s f u l p
r o j e c t o u t c o m e s b a s e d o n p r e d i c t e d
r e s o u r c e a l l o c a t i o n s t r a t e g i e s c o
n t r a c t a d m i n i s t r a t o r s c a n b e t t e r u
n d e r s t a n d t h e i m p a c t o f c o n t r a c t o r
f a i l u r e s t a t i s t i c a l l y s u p p o r t t h e
n o t i o n t h a t t h e i n c r e a s e d l e v e l o f t
r u s t b e t w e e n p a r t i e s l e a d s t o p r o j e
c t c o s t b e n e f i t s i d e n t i f y s u b s t a n t
i a l g a i n s i n p r o d u c t i v i t y , e a r l y d e
f e c t d e t e c t i o n , t i m e t o m a r k e t a n d q
u a l i t y b y i m p l e m e n t i n g C M M b a s e d s o
f t w a r e p r o c e s s i m p r o v e m e n t d e m o n s
t r a t e t h a t P M p r a c t i c e s p r o v i d e a t l
e a s t o n e w a y o f m a i n t a i n i n g t h e n e c e
s s a r y f o c u s w h i l e b r o a d e n i n g t h e f i
r m ' s b a s i s u n d e r s t a n d h o w c h a n g e o c
c u r s a n d a f f e c t s p r o j e c t h e t f e r u n d
e r s t a n d t h i ! J i n t l f t c U z I a n d o r g a n
i z a t i o n a t b e n e f i t s o f u s i n g P M p r a c
t i c e s i n c o r p o r { J t e o r g a n w t i o n s T a
b l e 1 . C o m p a r i s o n o f R e l a t e d R e s e a r
c h M e t h o d o l o g i e s
S A
P L
S I
Z E 7 5 p r o j e c t s ! 1 0 7 p r o j e c t s 2 6 2 p r o
j e c t s 1 3 o r g a n i z a t i o n s 3 1 7 f i r m s 1 0
4 p r o j e c t s Impacts of project management 261
5. Expected Results/Contributions
6. Conclusions
3. Kwak, Y.H., Clark, A., Grilo, A., Betts, M., and Ibbs,
C.W. (1995) Contemporary Strategic Planning Tools and
Applications for Construction Managers. First
International Conference on Construction Project
Management, Singapore, January, pp. 25-40.
Canada.
Vancouver, Canada.
Questionnaire.
THE APPLICATION OF
CONSTRUCT ABILITY PRINCIPLES IN
INDUSTRY
Adelaide, Australia
Sommaire
1 Introduction
constructability.
constructability.
en
o FEASIBILITY
z
w
..J
LL
:::i
iIi
<C
strategies.
problem.'
US and has been used as the basis for the research work by
the Construction Industry
3 Australian research
The only research had been by Hon [12] who found some
evidence of application of
industry.
actual savings.
DEFINITION
performance.
over which the project team has little control, but whose
influence can be minimised if
identified early.
study includes:
much progress since 1964 when Sir Harold Banwell said ' .
.in no other industry is the
8 Acknowledgments
T. Michael Lewis
Deogratius D. Mugishagwe
Abstract
Caribbean region.
Sommaire
1 Introduction
2 Scope
inevitable.
common wisdom was that a poor work ethic was the cause.
This was defined to mean
had been encountered and what their effects had been. His
interest was mainly in the
5 The Survey
6 Discussion of Results
involved with the high hire rates and the high custom
charges levied on imported
the recent economic upturn, firms did not have much trouble
finding work, but things
had been much more difficult until just a few years ago.
Recognising that one of the
7 Conclusion
seems clear that more of the blame lies with bad management
than with the bad 'work
INTEGRATING SITE-RELATED
SCHEDULING OF CONSTRUCTION
PROJECTS
Theophilus Adjei-Kumi
Glasgow, UK
Arkady Retik
Glasgow, UK
Aviad Shapira
which does not auger well with the effective planning and
scheduling of the totality of the building
activities' integration.
are required and take them off after they have served their
purpose. Some of these resources can be
values (if the user fails to provide them) which form the
basis of activity duration determination.
of occurrence.
methods.
Acknowledgement
Croatia, pp 375-380.
587-599.
pp.155-164.
1995,pp.172-182.
d h
. S
t n
n t
. = : ; N e t w o r k . . . . . , [ C O t l " f ) u t l . :
! r A p p J . o W B ' 0 C o n s . S c h t ! d . e B a r c h
a r t s ~ E S i l l ~ S i t e b l V . F o m l S n e P h o t
o . J S . V i s i t ~ o t o 2 0 3 0 4 0 5 0 6 0 A u r e g a
t e d P o i n t s F i g . 1 G e n e r a l i t e m s o f o p
e r a t i o n i n F i r m s I r v i a h : : r i a l s J ~ L
a b o u r • : " P l n n t I I Q f h c a d s 1 0 I L I I I I
I I 2 0 3 0 A g g r ~ g l l t ~ d P o i n t s ~ 4 0 5 0 o C
o m p r e h e n s i v e n e l l S • F n : q u e n c y F i g
. 3 C o m p a n y D a t a : C o m p r e h e n s i v e n e s
s a n d F r e q u e n c y o f R e v i s i o n B o q : J I .
S p e c s . ~~ D n l l n S S . Q " . 0 ' S . P l a n . t C
. o f I I I I I 1 0 2 0 3 0 4 0 5 0 6 0 A g g r ~ g l l k d
P o i n t s F i g . 2 I m p o r t a n c e a n d L e v e l o
f S t u d y o f P r o j e c t D o c u m e n t s S . V I S f
t S . V I S ' S ( ) I S ~ c e S i l l . ~ 2 P i n g . 0 . "
~ S I . D l 0 M ( . 1 h . M c t . h . S U l l l t S t n l l
l C o n s . S c h e d . o 2 0 4 0 6 0 2 0 4 0 6 0 8 0 1 0 0
A u " ' g a w d P o i n t s P e r c e n t a g r F i g . 4 T
h e U s e a n d U p d a t e o f D o c u m e n t s F i g . 5
T h e T i m i n g o f O p e r a t i o n s N o t e S . V i s
i t = S i t e V i s i t , S L D = S i t e L a y o u t D r a
w i n g s , L O B = L i n e o f B a l a n c e , C o m p u t
e r A p p l . = C o m p u t e r A p p l i c a t i o n s , M
e t h . S t m n ! . = M e t h o d S t a t e m e n t , S i t
e I n v . F o r m = S i t e I n v e s t i g a t i o n F o r
m , O I S P i n g . = O n s i t e P l a n n i n g , O l h e
a d s = O v e r h e a d s , C . o f C . = C o n d i t i o n
s o f C o n t r a c t , S . P l a n = S i t e P l a n , D r
w g s = D r a w i n g s , S p e c s . = S p e c i f i c a t
i o n s , B O Q = B i l l o f Q u a n t i t i e s , C o n s
. S c h e d . = C o n s t r u c t i o n S c h e d u l e C O
N S T R U C T I O N S C H E D U L E C O N S T R U C T I O N
P R O J E C T I N F O R M A T I O N E 1 1 ' C o n s t u c t
i o n s c h e d u l i n g t o o l ( e g . P r i m a v e r a
P r o j e c t P l a n n e r ) I n f o r m a t i o n e n t e
r e d e i t h e r m a n u a l l y ( u s i n g s c h e d u l
i n g t o o l ) o r s u p p l i e d a u t o m a t i c a l l
y t o s c h e d u l i n g t o o l b y k n o w l e d g e b a
s e S Y S T E M I N T E R F A C E I N T E L L I G E N T I N
T E R F A C E O b j e c t O r i e n t e d K n o w l e d g e
B a s e ( U s i n g K a p p a P C d e v e l o p m e n t A p
p l i c a t i o n ) C o n s t r o c t i o n a c t i v i t i
e s ' r e p r e s e n t a t i o n R e p r e s e n t a t i o
n o f c o n s t n l c t i o n m e t h o d s H e u r i s t i
c s B i d i r e c t i o n a l l i n k a g e t o e x t e m a
l a p p l i c a t i o n s A u t o m a t e d a c t i v i t y
g r a p h i c s l i n k a g e N O N I N T E L L I G E N T I
N T E R F A C E V i s u a l B a s i c I n t e r f a c e ( U
s i n g V i s u a l B a s i c T A l 3 . o d e v e l o p m e
n t a p p l i c a t i o n ) M a n u a l l i n k a g e o f a
c t i v i t i e s t o t h e i r g r a p h i c a l r e p r e
s e n t a t i o n s D e v e l o p m e n t o f u s e r s y s
t e m i n t e r f a c e F i g . 6 T h e m a i n c o m p o n
e n t s o f t h e P r o p o s e d S y s t e m G R A P H I C
S S U B S Y S T E M G r a p h i c a l L i b r a r y o f A c
t i v i t i e s ( U s i n g t h e S h a p e E d i t o r o f
S u p e r s c a p e ' s V R T o o l k i t ) P r e p a r e d
l i b r a r y o f g r a p h i c a l r e p r e s e n t a t i
o n o f c o n s t r o c t i o n a c t i v i t i e s O U T P
U T V I S U A L I S E R P r o j e c t i n a v i r t u a l e
n v i r o n m e n t u s i n g S u p e r s c a p e ' s V R T
V i s u a l u s e r
INFRASTRUCTURAL WORKS IN
RESIDENTIAL DEVELOPMENTS
S. Singh
Abstract
Sommaire
Le present papier discute les tendances en vigueur des
liquidites pour les
1 Introduction
other resources. Cooke & Jepson [1] and Harris & McCaffer
[2] have discussed the usefulness of
s-curves and Singh & Phua [3] have shown the importance of
establishing s-curves
294 Singh
be established.
4 Data Collection
conditions.
gasline installation
other figures.
298 Singh
8 Applications
9 Concluding Remarks
3. Singh, Sand Phua, W.W. (1984) Cash flow trends for high
rise building projects Proceedings oj the 4th
International Symposium on Organisation and Management oj
Construction, Waterloo (Canada), pp. 841-54.
150
100
50 10 20 30 40 50 60 70 80 90 100 CUMULATIVE %
TIME ~ BEST FIT EXCEPTION
120
1 Introduction
1.1 Background
1.2 Evaluation
report (1).
1.3 Terms
tor's responsibility .
2. Functional requirement
318 Hansson
tion as long as the client is aware that one then takes the
functional requirements
ActIVItIes
Actual course
Design
Stage 4.5 10 km
~tage 10 HS km
General contract
IAlternatIve course
IDeslgn
Procurement IIIIIIIIIIIII
l onstrucUon
320 Hansson
was in this case carried out for approx. 1/3 of the road
when work as started. The contractor's point of view
should be set against this, i.e. it is more important
NEWROAD94:
ners:
Advantages
Disadvantages
4. Organisation
Advantages:
Disadvantages:
contractor
tration
Production East +
Skanska
General
client.
Advantages:
Disadvantages:
5. Construction
6. Economic consequences
costs that were not quite SEK 20 million lower than what a
traditional general con
Cost Summary
Knowledge changes
construction contract.
Functional requirement
ence.
Residual value
be studied further.
Administrative experiences
AND PRACTICE
G.S. Birrell
ABSTRACT
French features.
SOMMAIRE
UK.
features.
of contractors.
This can span from economic and financial for the client to
functionality and satisfaction of the users
procurement
bUilding.
Design Phase
client and the project manager with some input from the
conceptual designer. The past experiences
for that position on the project team. Each bidder will bid
for the construction of the whole building
Construction Phase
Design Phase
manager.
deciding factors.
Construction Phase
Design Phase
Then the architect will develop the design and produce the
documents required for
trades works and who knows and is known by all the local
sub contractors. The architect usually
in each trade given their skills, current work load and his
experience of their performance on past
Construction Phase
Complex/Large Approach
Simple/Small Approach
334 Birrell
USA approaches.
Conceptual Design
procurement durations.
Project Management
process.
Design Competition
and experience and then he carries out the design work for
this project which may include writing the
1. Introduction
phases.
involves both the firms leaming who and how they need to
work with others, and how
4. Project integrators
5. Conclusion
2 Resources
2.2 Energy
and considering that iron and steel were excluded from this
calculation it is probable that
the potential saving achievable is significant. Connaugton
(1987) compared energy
2.3 Pollution
material, and the main scope for reducing this comes from
substituting materials with
2.4 Waste
Recycle it.
Treat it.
Dispose of it.
concrete floor.
The paper does not suggest that these figures can be taken
as anything other than a
5 Conclusion.
CONSTRUCTION PROCUREMENT
CONTRACT DISPUTES
Glasgow, UK
P.Kennedy
Summary
Background
1986).
industry.
The research which has been carried out so far into the
extent of construction conflict has been useful
Objectives
The main objective of the research project was to widen the
understanding of conflict in the UK
Sources of Conflict
Causes of Conflict
Effects of ConOict
conflict.
construction industry.
Methodology
use in the UK, the main forms of contract used in the UK, a
range of client types, project values,
Performance
Negligence
project.
subgroup.
working methods(0.50).
Administration
Conclusion
within the delay and time group. It was shown that, within
the delay and time group and negligence
traditional projects.
projects
Spon, London
London.
ARCOM
Tobago et revoit les essais pour obtenir des fonds pour ces
besoins infrastructural. Ce travail discute
1 Introduction
decade and a half ago (1980). the dominant stream was from
publicly guaranteed private loans (50
bilateral loans.
raise rate, inviting the public to peruse and study all the
supporting documentations in their
which new rate and for how long. It has generally been felt
that the reason why rates have not been
1983, the fund was discontinued and the money in the fund
returned to the consolidated fund to deal
fee to permit use of the route. The route was also opened
to VIPs who had to be granted special
376 Suite
378 Suite
borne fruit. The quest for the US$75 million has not been
successful after more than two years since
(ii) Since the driving force for the new philosophy in the
infrastructure/utilities market place must be based on
the ability to pay that priority industrial and commercial
activities, generating foreign exchange say, or involved
in the export thrust or a favoured sector will have
greater access to service before principally
domestic/residential communities. There is the danger
which already has begun to appear that social and
collective needs may not always qualify for priority under
the strict application of market analysis, economic
financial justifiability and return on investment criteria.
resolution.
Sommaire
Pendent des ans 1974 et 1983, Trinite et Tobago eprouve une
grande hausse en construction.
382 Suite
1 Introduction
1. The Architect
While there have been several calls over the last ten years
to APETT to initiate the
conflict.
384 Suite
courts.
2.1 Conciliation
2.2 Mediation
2.3 Mini-Trials
2.4 Adjudication
arrive at a solution.
practice has drifted more and more into being very similar
in form and operation to the high
386 Suite
exchanged.
P
r e
s e
n t
o u
t e
p l
o y
e d r E N D ~ E N D \ I ; t ~ I C o n c i l i a t i o n l ~
I T I M i n i T r i a l ~ R r b i t r a t i o n I ~ E N D D
i s p u t e \ l I E N D ( C o n s u l t a n t C o C o n t r
a c t o r R e s o l u t i o n ) ~ ~ 1 > 1 M e d i a t i o n
I + " ' f ~ \ I I 4 E N D , ~ , . . F i g . 1 . A l t e r n
a t i v e D i s p u t e R e s o l u t i o n F l o w R d j u
d i c a t i o n 1 t \ 4 ' 1 1 1 1 1 1 1 1 1 1 1 1 I > E N D
1 1 1 1 1 11 1 \ V l i t i g a t i o n I ~ E N D
Alternative dispute resolution methods 389
disputes.
390 Suite
R.W. Craig
University, UK
P. Davenport
Sydney, Australia
Abstract
Sommaire
Ce papier approfondit la cause de la maison Pratt
Contractors en Nouvelle-Zelande
1 Introduction
accept Pratt's tender. But the court did not find any
conflict in the several provisions within the tender
4 Quantum of damages
The court had thus found for the plaintiff tenderer against
the Council. It remained only
contract.
price over budget. They also contended that had Pratt been
awarded the contract they
costs.
the gain.
only was this wasted cost expended before the breach but
some part was expended
resultant gain.
contributor disagrees.
7 Conclusion
request for tenders. But what does "within the scope of'
mean? Subsequently a
management.
10 Ibid. at 480116.
15 Ibid. at 483/4.
16 Ibid. at 483/34-41.
20 Ibid. at 489122-26.
25 Ibid. at 692c.
35 Ibid at 486/7.
28. Id.
29. See, e.g., AlA Document A201, supra, note 12, " 4.2,
4.3.
where:
similar to the basic price forecast model for 'P' (Eq. 2).
Costs are usually current with little
section represent?
bills of quantities.
Project value 0 8 0 29 33 29 48 21 19 13
Project size 0 4 0 21 11 17 63 42 26 17
Contract duration 0 4 0 0 11 17 37 29 52 50
Location 0 4 12 4 35 38 35 38 19 17
Expected number 15 33 35 21 39 25 8 17 4 4
of bidders
State of market 0 17 23 25 15 33 27 17 35 8
Quality of tender 0 13 23 33 46 21 31 17 0 17
information
Project timing 0 9 19 9 31 44 31 26 15 13
Project complexity 0 0 4 13 27 21 46 54 23 13
Client organisation 8 8 39 33 54 17 0 29 0 13
accommodation
lighting
Scaffolding 5-10 5
boards
storage facilities)
Cleaning 5 0-5
Conclusions
professional.
4 Research methodology
Having looked the characteristics of both clients and
construction professionals the
4.5 Results
CCI8A++ 1.86 0.02 0.74 0.02 0.40 CCI8B 4.65 0.02 0.00
0.00 0.00 CCI8B+ 1.49 0.02 1.12 0.02 0.75 CCI8C+ 6.98
0.02 0.00 0.00 0.00 CCI9 10.53 0.62 17.67 0.59 0.83 OCV
Original Contract Value 454 Kumaraswamy Table 2(a).
Perceived significance of common categories of construction
claims (as perceived by contractors, clients and
consultants; and listed in descending order of overall
perceived significance) Overall Contractors Clients
Consultants Rank Index Rank Index Rank Index Rank
Index Variations due to site conditions 58.2 1 67.5 2
48.6 4 58.6 Variations due to client changes 2 55.6 2
60.0 4 46.7 1 60.0 Variations due to design errors 3 54.4
3 47.5 1 57.1 3 58.6 Unforeseen ground conditions 4 49.0
4 42.0 5 45.0 2 41.9 Ambiguities in contract documents 5
43.0 6 30.0 3 47.6 9 51.4 Variations due to external
events 6 40.6 5 37.5 7 40.0 10 44.3 Interference with
utility lines 7 40.5 7e 30.0 6 40.0 8 51.4
Exceptional inclement weather 8 40.2 9 30.0 9 36.2 5
54.3 Delayed site possession 9 39.4 7e 30.0 10 35.2 6
52.9 Delayed design information 10 34.5 12 12.5 8 38.1 7
52.9 Table 2(b). Perceived significance of common causes
of claims (as perceived by contractors, clients and
consultants; and listed in descending order of overall
perceived significance) Cause Overall Contractors Clients
Consultants Rank Index Rank Index Rank Index Rank
Index Inaccurate design information 1 57.3 1 62.5 4 45.3
1 64.3 Inadequate design information 2 50.6 4 50.0 2
54.3 5 54.3 Inadequate site investigations 3 49.3 5
50.0 5 42.1 4 55.7 Slow client response (decisions) 4 46.9
3 50.0 11 37.9 6 52.9 Poor communications 5 45.7 10 40.0
12 35.8 2 61.4 Unrealistic time targets 6 45.0 2 52.5
7 41.1 12 41.4 Inadequate contract administration 7 44.6
15 30.0 3 45.3 3 58.6 Uncontrollable external events 8
44.1 12 35.0 1 51.6 10 45.7 Incomplete tender
information 9 41.9 6 42.5 13 34.7 8 48.6 Unclear risk
allocation 10 41.3 7e 40.0 6 41.1 11 42.9 Table 2(c).
Perceived effectiveness of dispute resolution methods (as
perceived by contractors,
them.
3. 1 Project organisation
with its own goals and values, were all drawn together in
the achievement of a task.
be changed.
mechanisms
construction project.
entreprises.
2.1 Questionnaire
• contract administration.
3.2 Communication
3.3 Feedback
The next question asked the SC's to rate the feedback that
they received on their tenders,
from MC's who you do not wish to work for?" 76% (13117) of
the respondents stated that they did get enquiries from
MC's who they did not want to work for. Question 2 asked
the interviewees whether they were invited to tender for
Be or did the enquiry simply arrive unannounced. 53% (9)
of the respondents believed that
same.
Tendering
contracts' .
better than most and (7/16) thought BC were about the same
as the rest. None of the
4.0 Conclusions
It was apparent from this study that there are many areas
in which BC and main
to better relationships.
3 Method
4 Results
Abstract
Resume
controle.
1 Design quality
that product.
implemented.
following [3]:
the building;
design quality.
presented.
design.
technological errors;
design process;
implementing.
4 Conclusion
DESIGN
Bob G. McCuliouch
Indiana, USA
ABSTRACT
510 McCullouch
Sommaire
individuel.
Introduction
etc. [5]
Ardery [8] found they will payoff 10-20 times the cost of
the progr.am. The
512 McCullouch
Tool Description
514 McCullouch
516 McCullouch
Tool Distribution
Windows 3.x but it also runs under Windows 95. It has been
tested on a 486
Final Summary
designer environment.
CONSTRUCTION
Sweden
Abstract
Sommaire
1 Introduction
production [1] [2] [3] [4]. In our first study, the defect
cost in one building project was
also in design [4] [9] [10] [11] [12]. In our first study,
54% of the defect cost could be
2 Frame of reference
Client
Design
Production
Material
Maintenance
2.2.1 Cause
you have gained because you have worked at the job for a
long time [24]. Information
[25].
3 The method
table 2.
4 Results
Average 6 26 12 9 28 10 4 4
Actor Know
Design
Site management
Workmanship
Subcontractors
defects. The method for the study has been chosen with the
intention of collecting a variety
further analyses.
VALUE MANAGEMENT
Abstract
methodology.
Sommaire
1 Introduction
3 Decision-making groups
decision contexts.
8 Research results
9 Conclusion
10 Acknowledgement
acknowledged.
INTERNATIONAL COMPARISON OF
Adelaide, Australia
C.M. Tam
Abstract
Sommaire
1 Introduction
worth correspond".
obtained:
1 . Review of literature.
I Lay days are the free days allowed between the workshop
meetings for in-depth investigation and refinement of
ideas generated or discussed during the workshops.
December 1991. The study lasted for one full day and two
half days with two lay days
in between. It was the client's initiative to have a value
management study for this
major purposes:
implemented.
Shaw and Chan [9]. The study was undertaken when the
design was 100% completed and
workshop by:
7 Conclusion
of organisational members.
improve output.
communication is sought.
contingencies).
professionals development
innovation.
indeterminate fashion.
colleagues.
sample.
7 Summary
9 p.56-67
design team.
vol 9, p.56-67.
p.1l-39, vol 2.
HMSO.
Graham Miller
Abstract
Australia.
design.
Sommaire
architectural certain.
1 Introduction
Client management of the design process can take many
forms, from total
Australia.
2 Summary of Findings
process generally.
similar departments.
b) the architect
to tender.
2.2.8 Costs
etc.
2.3 Time
Inception(28.7%)
Feasibility(13.5%) Outline(7.6%)
Tender Acfn(2.1 %)
570 Miller
3 Conclusion
Scheme 00.(92.9%)
Tender Ac1n(92.9%)
Complotion(65.7%)
PROCESS OF INNOVATION
England, Bristol, UK
D.A. Langford
Glasgow, UK
Abstract
Innovation is the new buzzword in the construction
industry. The importance of
Behaviour.
Sommaire
creativite.
1 Introduction
innovate and develop new ideas does not relate to the old
model of organisations.
4 Discussion
system which has been also developed over the last 30 years
for completely
14. Ibid.
Kegan, London.
of the schedule.
(15).
among a activities.
Methodology:
(Table 2).
Reconstructi on
This study shows that the report system for top management
about construction
1.0 Introduction
2.0 Curriculum
TABLE 1
Education 33 36.26
Public Sectors
Industries 18 19.77
Commerce 17 18.68
Consultants 4 4.39
Others 7 7.69
Total 91 100
5.0 Discussion
Torrance, V.B., Okoroh, M.I., Quah, L.K. & Teo, H.P. (1991)
An Expert System for Tendering and Bidding in
Reforbishment Contracts, Proc. European Symposium on
York.