Parking Studies

Lecture Notes in Transportation Systems Engineering

Prof. Tom V. Mathew∗

Contents
1 Overview 1

2 Parking system 1
2.1 On street parking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
2.2 Off street parking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3 Parking requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.4 Ill effects of parking . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

3 Parking statistics 5

4 Parking surveys 7
4.1 In-out survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2 License plate method of survey . . . . . . . . . . . . . . . . . . . . . . . . . . 9

5 Summary 11

6 Acknowledgments 12

1 Overview
Parking is one of the major problems that is created by the increasing road traffic. It is an
impact of transport development. The availability of less space in urban areas has increased
the demand for parking space especially in areas like Central business district. This affects
the mode choice also. This has a great economical impact.

2 Parking system
∗
IIT Bombay (tvm@civil.iitb.ac.in) March 8, 2017

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 L
5.9
2.5

5.0

Figure 1: Illustration of parallel parking

2.1 On street parking

On street parking means the vehicles are parked on the sides of the street itself. This will be
usually controlled by government agencies itself. Common types of on-street parking are as
listed below. This classification is based on the angle in which the vehicles are parked with
respect to the road alignment. As per IRC the standard dimensions of a car is taken as 5×
2.5 meters and that for a truck is 3.75× 7.5 meters.

1. Parallel parking: The vehicles are parked along the length of the road. Here there
is no backward movement involved while parking or unparking the vehicle. Hence, it
is the most safest parking from the accident perspective. However, it consumes the
maximum curb length and therefore only a minimum number of vehicles can be parked
for a given kerb length. This method of parking produces least obstruction to the on-
going traffic on the road since least road width is used. Parallel parking of cars is
N
shown in figure 1. The length available to park N number of vehicles, L = 5.9

2. 30◦ parking: In thirty degree parking, the vehicles are parked at 30◦ with respect to the
road alignment. In this case, more vehicles can be parked compared to parallel park-
ing. Also there is better maneuverability. Delay caused to the traffic is also minimum in
this type of parking. An example is shown in figure 2. From the figure,

AB = OBsin30◦ = 1.25,
BC = OP cos30◦ = 4.33,
BD = DQcos60◦ = 5,
CD = BD − BC = 5 − 4.33 = 0.67,
AB + BC = 1.25 + 4.33 = 5.58

For N vehicles, L = AC + (N-1)CE =5.58+(N-1)5 =0.58+5N

3. 45◦ parking: As the angle of parking increases, more number of vehicles can be
parked. Hence compared to parallel parking and thirty degree parking, more number
of vehicles can be accommodated in this type of parking. From figure 3, length of
parking space available for parking N number of vehicles in a given kerb is L = 3.54
N+1.77

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 1.25 4.33 L 1.25 m

A B CD E
30
O .... n 4.66 m
1Q 2
P
5m

m
5
2.
Figure 2: Illustration of 30◦ parking
1.77
45
5.31 m
5.
0

m
m

5
2.
Figure 3: Illustration of 45◦ parking

4. 60◦ parking: The vehicles are parked at 60◦ to the direction of road. More number of
vehicles can be accommodated in this parking type. From the figure 4, length available
for parking N vehicles =2.89N+2.16.

5. Right angle parking: In right angle parking or 90◦ parking, the vehicles are parked
perpendicular to the direction of the road. Although it consumes maximum width kerb
length required is very little. In this type of parking, the vehicles need complex ma-
neuvering and this may cause severe accidents. This arrangement causes obstruction
to the road traffic particularly if the road width is less. However, it can accommodate
maximum number of vehicles for a given kerb length. An example is shown in figure 5.
Length available for parking N number of vehicles is L = 2.5N.

60

2.5m

Figure 4: Illustration of 60◦ parking

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 L

2.5

Figure 5: Illustration of 90◦ parking

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Figure 6: Illustration of off-street parking

2.2 Off street parking

In many urban centers, some areas are exclusively allotted for parking which will be at some
distance away from the main stream of traffic. Such a parking is referred to as off-street
parking. They may be operated by either public agencies or private firms. A typical layout of
an off-street parking is shown in figure 6.

2.3 Parking requirements

There are some minimum parking requirements for different types of building. For residential
plot area less than 300 sq.m require only community parking space. For residential plot area
from 500 to 1000 sq.m, minimum one-fourth of the open area should be reserved for parking.
Offices may require at least one space for every 70 sq.m as parking area. One parking space
is enough for 10 seats in a restaurant where as theatres and cinema halls need to keep only
1 parking space for 20 seats. Thus, the parking requirements are different for different land
use zones.

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2.4 Ill effects of parking

Parking has some ill-effects like congestion, accidents, pollution, obstruction to fire-fighting
operations etc.

1. Congestion: Parking takes considerable street space leading to the lowering of the
road capacity. Hence, speed will be reduced, journey time and delay will also sub-
sequently increase. The operational cost of the vehicle increases leading to great
economical loss to the community.

2. Accidents: Careless maneuvering of parking and unparking leads to accidents which

are referred to as parking accidents. Common type of parking accidents occur while
driving out a car from the parking area, careless opening of the doors of parked cars,
and while bringing in the vehicle to the parking lot for parking.

3. Environmental pollution: They also cause pollution to the environment because

stopping and starting of vehicles while parking and unparking results in noise and
fumes. They also affect the aesthetic beauty of the buildings because cars parked at
every available space creates a feeling that building rises from a plinth of cars.

4. Obstruction to fire fighting operations: Parked vehicles may obstruct the move-
ment of firefighting vehicles. Sometimes they block access to hydrants and access to
buildings.

3 Parking statistics
Before taking any measures for the betterment of conditions, data regarding availability of
parking space, extent of its usage and parking demand is essential. It is also required to
estimate the parking fares also. Parking surveys are intended to provide all these informa-
tion. Since the duration of parking varies with different vehicles, several statistics are used
to access the parking need. The following parking statistics are normally important.

1. Parking accumulation: It is defined as the number of vehicles parked at a given

instant of time. Normally this is expressed by accumulation curve. Accumulation curve
is the graph obtained by plotting the number of bays occupied with respect to time.

2. Parking volume: Parking volume is the total number of vehicles parked at a given
duration of time. This does not account for repetition of vehicles. The actual volume of
vehicles entered in the area is recorded.

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 3. Parking load : Parking load gives the area under the accumulation curve. It can also
be obtained by simply multiplying the number of vehicles occupying the parking area
at each time interval with the time interval. It is expressed as vehicle hours.

4. Average parking duration: It is the ratio of total vehicle hours to the number of
vehicles parked.
parking load
parking duration = (1)
parking volume
5. Parking turnover: It is the ratio of number of vehicles parked in a duration to the
number of parking bays available. This can be expressed as number of vehicles per
bay per time duration.
parking volume
parking turnover = (2)
no. of bays available

6. Parking index: Parking index is also called occupancy or efficiency. It is defined as

the ratio of number of bays occupied in a time duration to the total space available. It
gives an aggregate measure of how effectively the parking space is utilized. Parking
index can be found out as follows
parking load
parking index = × 100 (3)
parking capacity

3.0.1 Numerical Example

To illustrate the various measures, consider a small example in figure 7, which shows the
duration for which each of the bays are occupied(shaded portion). Now the accumulation
graph can be plotted by simply noting the number of bays occupied at time interval of 15,
30, 45 etc. minutes is shown in the figure. The various measures are calculated as shown
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Bays and occupancy
No. of vehicles

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2
1

0 15 30 45 60 75 90 105 110 Time

Parking accumulation curve

Figure 7: Parking bays and accumulation curve

below: Parking volume is given as 5 vehicles. Parking load is given as (1 + 2 + 1 + 0 + 1 +

2 + 3 + 1) 15
60
= 11×15
60
= 2.75 veh hour. Average parking duration is computed as 2.75 veh hours
5veh
=
5 veh/2 hours
33 minutes. Parking turnover is obtained as 3bays
= 0.83 veh/hr/bay. Parking index is
2.75 veh hour
calculated as 3×2 veh hours
× 100= 45.83%

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4 Parking surveys
Parking surveys are conducted to collect the above said parking statistics. The most com-
mon parking surveys conducted are in-out survey, fixed period sampling and license plate
method of survey.

4.1 In-out survey

In this survey, the occupancy count in the selected parking lot is taken at the beginning. Then
the number of vehicles that enter the parking lot for a particular time interval is counted. The
number of vehicles that leave the parking lot is also taken. The final occupancy in the parking
lot is also taken. Here the labor required is very less. Only one person may be enough. But
we wont get any data regarding the time duration for which a particular vehicle used that
parking lot. Parking duration and turn over is not obtained. Hence we cannot estimate the
parking fare from this survey. For quick survey purposes, a fixed period sampling can also
be done. This is almost similar to in-out survey. All vehicles are counted at the beginning of
the survey. Then after a fixed time interval that may vary between 15 minutes to i hour, the
count is again taken. Here there are chances of missing the number of vehicles that were
parked for a short duration.

4.1.1 Numerical Example

From an in-out survey conducted for a parking area consisting of 40 bays, the initial count
was found to be 25. Table gives the result of the survey. The number of vehicles coming in
and out of the parking lot for a time interval of 5 minutes is as shown in the table 1. Find the
accumulation, total parking load, average occupancy and efficiency of the parking lot.

Solution The solution is shown in table 2

• Accumulation can be found out as initial count plus number of vehicles that entered the
parking lot till that time minus the number of vehicles that just exited for that particular
time interval. For the first time interval of 5 minutes, accumulation can be found out as
25+3-2 = 26. It is being tabulated in column 4.

• Occupancy or parking index is given by equation For the first time interval of five min-
26
utes, P arking index = 40
× 100 = 65%. The occupancy for the remaining time slot is
similarly calculated and is tabulated in column 5. Average occupancy is the average of
the occupancy values for each time interval. Thus it is the average of all values given
in column 5 and the value is 80.63%.

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 Table 1: In-out survey data
Time In Out
5 3 2
10 2 4
15 4 2
20 5 4
25 7 3
30 8 2
35 2 7
40 4 2
45 6 4
50 4 1
55 3 3
60 2 5

Table 2: In-out parking survey solution

Time In Out Accumulation Occupancy Parking load
(1) (2) (3) (4) (5) (6)
5 3 2 26 65 130
10 2 4 24 60 120
15 4 2 26 65 130
20 5 4 27 67.5 135
25 7 3 31 77.5 155
30 8 2 37 92.5 185
35 2 7 32 80 160
40 4 2 34 85 170
45 6 4 36 90 180
50 4 1 39 97.5 195
55 3 3 39 97.5 195
60 2 5 36 90 180
Total 1735

• Parking load is tabulated in column 6. It is obtained by multiplying accumulation with

the time interval. For the first time interval, parking load = 26 × 5 = 130 vehicle minutes.

• Total parking load is the summation of all the values in column 5 which is equal to 1935

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 vehicle minutes or 32.25 vehicle hours

4.2 License plate method of survey

This results in the most accurate and realistic data. In this case of survey, every parking stall
is monitored at a continuous interval of 15 minutes or so and the license plate number is
noted down. This will give the data regarding the duration for which a particular vehicle was
using the parking bay. This will help in calculating the fare because fare is estimated based
on the duration for which the vehicle was parked. If the time interval is shorter, then there
are less chances of missing short-term parkers. But this method is very labor intensive.

4.2.1 Numerical Example

The parking survey data collected from a parking lot by license plate method is s shown in
the table 3 below. Find the average occupancy, average turn over, parking load, parking
capacity and efficiency of the parking lot.

Table 3: Licence plate parking survey data

Bay Time
0-15 15-30 30-45 45-60
1 1456 9813 - 5678
2 1945 1945 1945 1945
3 3473 5463 5463 5463
4 3741 3741 9758 4825
5 1884 1884 - 7594
6 - 7357 - 7893
7 - 4895 4895 4895
8 8932 8932 8932 -
9 7653 7653 8998 4821
10 7321 - 2789 2789
11 1213 1213 3212 4778
12 5678 6678 7778 8888

Solution See the following table for solution 4. Columns 1 to 5 is the input data. The
parking status in every bay is coded first. If a vehicle occupies that bay for that time interval,
then it has a code 1. This is shown in columns 6, 7, 8 and 9 of the table corresponding to
the time intervals 15, 30, 45 and 60 seconds.

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 Table 4: Licence plate parking survey solution
Bay Time Time
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10)
15 30 45 60 15 30 45 60 Turn over
1 1456 9813 - 5678 1 1 0 1 3
2 1945 1945 1945 1945 1 1 1 1 1
3 3473 5463 5463 5463 1 1 1 1 2
4 3741 3741 9758 4825 1 1 1 1 3
5 1884 1884 - 7594 1 1 0 1 2
6 - 7357 - 7893 0 1 0 1 2
7 - 4895 4895 4895 0 1 1 1 1
8 8932 8932 8932 - 1 1 1 0 1
9 7653 7653 8998 4821 1 1 1 1 3
10 7321 - 2789 2789 1 0 1 1 2
11 1213 1213 3212 4778 1 1 1 1 3
12 5678 6678 7778 8888 1 1 1 1 4
Accumulation 10 11 9 11
Occupancy 0.83 0.92 0.75 0.92 2.25

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 • Turn over is computed as the number of vehicles present in that bay for that particular
hour. For the first bay, it is counted as 3. Similarly, for the second bay, one vehicle is
present throughout that hour and hence turnout is 1 itself. This is being tabulated in
Sum of turn−over
column 10 of the table. Average turn over = Total number of bays
= 2.25

• Accumulation for a time interval is the total of number of vehicles in the bays 1 to 12 for
that time interval. Accumulation for first time interval of 15 minutes = 1+1+1+1+1+0+0+1+1+1+1+1
= 10

• Parking volume = Sum of the turn over in all the bays = 27 vehicles

• Average duration is the average time for which the parking lot was used by the vehicles.
It can be calculated as sum of the accumulation for each time interval × time interval
divided by the parking volume = (10+11+9+11)×15
27
= 22.78 minutes/vehicle.

• Occupancy for that time interval is accumulation in that particular interval divided by
total number of bays. For first time interval of 15 minutes, occupancy = (10×100)/12 =
83% Average occupancy is found out as the average of total number of vehicles occu-
pying the bay for each time interval. It is expressed in percentage. Average occupancy
0.83+0.92+0.75+0.92
= 4
× 100 = 85.42%.

• Parking capacity = number of bays × number of hours = 12× 1 = 12 vehicle hours

• Parking load = total number of vehicles accumulated at the end of each time interval ×
(10+11+9+11)×15
time = 60
= 10.25 vehicle hours

Parking load 10.25

• Efficiency = Total number of bays
= 12
= 85.42%.

5 Summary
Providing suitable parking spaces is a challenge for traffic engineers and planners in the
scenario of ever increasing vehicle population. It is essential to conduct traffic surveys in
order to design the facilities or plan the fares. Different types of parking layout, surveys and
statistics were discussed in this chapter.

Acknowledgments
I wish to thank several of my students and staff of NPTEL for their contribution in this lecture.

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6 Acknowledgments
I wish to thank several of my students and staff of NPTEL for their contribution in this lecture.
I also appreciate your constructive feedback which may be sent to tvm@civil.iitb.ac.in

Prof. Tom V. Mathew

Department of Civil Engineering
Indian Institute of Technology Bombay, India

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