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

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

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

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

Accumulation Curve Accumulation (veh) Time (hrs) 6 9 12 15 18 21 24 3 6

Demand vs. Supply Maximum Demand No. of Legal Spots Accumulation (veh) Time (hrs) Accumulation (veh) 6 9 12 15 18 21 24 3 6 No. of Legal Spots True Demand

Demand vs. Supply Hidden Demand Accumulation (veh) Illegal Parking Time (hrs) Accumulation (veh) 6 9 12 15 18 21 24 3 6 Hidden Demand Illegal Parking

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

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

Parking Inventory Summary Sheet 6 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

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)

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

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

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

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

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

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

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

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

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