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Parking surveys are conducted to collect the above said parking statistics.
The most common parking surveys conducted are in-out survey, fixed period
sampling and license plate method of 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.
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.
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 |
The solution is shown in table 2
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 |
- 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 minutes,
 = 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%.
- 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 vehicle minutes or 32.25 vehicle hours
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