1. School of Civil Engineering
Highway Traffic and Safety Analyses
Lecture 7: Parking Studies
Purdue University
School of Civil Engineering
West Lafayette

2. Lecture Outline Definitions Demand vs. Supply Parking Inventory
Accumulation Studies
License Plate Checks

3. Definitions Parking volume (veh/day) Parking accumulation (veh)
Number of vehicles parking in a study area during a specific length of time (typically a day). Vehicles leaving the parking area and returning are counted twice.
Parking accumulation (veh)
Number of vehicles parking at a specific time
Parking accumulation curve
A curve showing variation of parking accumulation over time

4. Definitions Parking load (veh-hour) Parking duration (hour)
The area under the parking accumulation curve
Parking duration (hour)
Average parking time
Parking turnover (veh/space)
Number of vehicles per parking space during the analyzed period

5. Accumulation Curve Accumulation (veh) Time (hrs)

6. Demand vs. Supply Maximum Demand No. of Legal Spots Accumulation (veh)
Time (hrs)
Accumulation (veh)
No. of Legal Spots
True Demand

7. Demand vs. Supply Hidden Demand Accumulation (veh) Illegal Parking
Time (hrs)
Accumulation (veh)
Hidden Demand
Illegal Parking

8. Parking Inventory Number of parking spaces
Time limits and hours of operation
Type of ownership
Rates and method of fee collection
Parking regulations at curb spaces (loading zones, passenger zones, handicapped zones, taxi zones, bus zones)
Lot or garage
Degree of permanency

9. Parking Inventory Numbering System
Curb Face Number 1 2 4 3
Block Number 6 7 5 6 7 5
Off-Street Facility Number

10. Parking Inventory Summary Sheet6 5 1 2 4 3 7
Block Number
Curb Face Number
Off-Street Facility Number
Parking Inventory Summary Sheet
Block
Facility
Inventory Data
Parking Spaces
Non-public Spaces
Data 3
Data 4
Data 5
….. 5 1 7 2 12 3 6 4

11. Area and Time of Parking Accumulation Studies
Study area – parking area for the studied development
On days when maximum parking is expected
Counting period should include time of intense parking
6 AM to 8 PM for employment and commercial sites (several times)
1 AM to 5 AM should be covered in residential areas (once)

12. Techniques of Parking Demand Studies
Cordon-based without vehicles identification
Cordon-based with vehicles identification
Route-based without vehicles identification
Route-based with vehicles identification

13. Cordon-Based Parking Study without Vehicles Identification
Estimating the initial accumulation by counting along routes
Continuous counting of vehicles entering and exiting the study area
Estimating the final accumulation by counting along routes

14. Cordon-Based Parking Study with Vehicles Identification
Estimating the initial accumulation by counting along routes
Manual recording of license numbers when low flows
Videotaping of license numbers with post-processing when large flows
Estimating the final accumulation by counting along routes

15. Route-Based Accumulation Studies without Vehicles Identification
Counting along a pre-specified route that covers the study area
Careful routes design for large areas (multiple field checkers)
Counting vehicles or empty spaces (what easier)
Counting interval: one or two hours
5-hour shifts
Common starting point helps supervising

16. Route-Based Accumulation Studies with Vehicles Identification
Hand-held computers, tape recorders, or paper worksheets
Counting interval: 1/3 of the average parking duration and not longer than 1-2 hours
1 ½ minutes per one parking space needed
5-hour shifts
Careful routes design for large areas (multiple field checkers)
Common starting point helps supervising

17. Exercise 1 Parking vehicles were counted every two hours
Draw a parking accumulation curve, calculate the parking load based on the parking counts.

18. License Plate Checks Calculations
Turnover = Parking Volume/Parking Spaces
Parking Load =
Av. Accumulation x No. of Intervals x Av. Interval
Average Parking Duration =
Parking Load/Parking Volume

19. Exercise 2 The license plates were noted every two hours.
Determine the parking volume and calculate the parking turnover and the average parking duration.

20. Results Obtainable from Various Parking Study Techniques
Cordon without Identification
Cordon with Identification
Routes without Identification
Routes with Identification
Accumulation
Yes
Volume No
Turnover
Average Duration
Variability of Duration
Space use
Illegal parking
Yes/No
Enforcement