TEM-202: Transportation Planning

Lecture Series: Parking Planning and Management

Lecture 1: Types of parking and parking studies

Date: 04.03.2013

Instructor: Dr. Zahara Batool

Planning for Parking Introduction

Parking Policy

Parking Method

Parking Studies

Parking measurement and analysis

Key Terms

BackgroundParking is an important urban transportation element.

It affects mode choice (parking availability, accessibility, cost

of parking).

It affects the vitality of communities, commercial and

business centers, transit system and airports as well as the

efficiency of traffic circulation in downtown areas.

It has certain direct economic activities.

Types of Parking Methods The Parking Methods play a major role in controlling traffic and

avoid chaotic confusion and traffic jams because of lack of

Parking facility.

On Street Parking

Off Street Parking

On-Street Parking As the name itself suggests, “On-street Parking” means the

area allotted for Parking purpose at the sides of the roads.

For efficiency in Parking system; the On street Parking is

divided into following types:

Parallel Parking

Angular Parking

Perpendicular Parking (efficient Parking Method)

On-street Parking

Parallel Parking System The vehicles are parked one behind the other.

It has been surveyed that the area required for Parallel

Parking is much lesser that required for Angular Parking.

Therefore, more number of vehicles can be parked in this

Parking System.

For this reason, this Parking system is generally adopted.

Parallel Parking System

Angular Parking The vehicles are parked at an angle. It may be a 30 degree angle or

45 degree.

The vehicles can be easily reversed if parked at an angle. Hence,

proving as an efficient Parking System in case of vehicular

circulation.

The major drawback of “Angular Parking System” is that it requires

larger space for parking than required for Parallel Parking.

Hence this system is adopted where the space is available in plenty.

Angular Parking

Perpendicular Parking The vehicles are parked at right angle to the road.

It is an efficient system of Parking.

Perpendicular Parking

Off Street ParkingAs the name suggests, Off street Parking means a Parking

Area is designed adjacent to the Road or in a place or building

which is not the part of the road.

Parking lots

Bypass road

Multistory Building Garage

Parking Lanes

Supply and DemandParking supply is merely the number and location of all parking

spaces in the study area.

The supply is defined by the parking inventory (described later).

Supply is much easier to quantify than is demand because it is a

physical count.

Supply is generally constant, although there can be some changes

during the day (e.g., tow away zones during peak hours, part-time

loading zones, etc.).

Supply and DemandDemand, on the other hand, is an estimate of the number of drivers who wish

to park in the study area at any given time.

Demand varies by time. In fact, one of the elements to be defined in the study

is the time of peak demand.

In some areas there may be multiple peaks because of the differing uses within the

study area. A simple example is an office complex. The peak employee accumulation

may be by 9:00 A.M., while the peak client or visitor accumulation may be 11:30 A.M.

or 2:30 P.M. Deliveries or service personnel may peak at still different times.

Parking StudiesParking studies are needed to be conducted

in order to collect information about the capacity of existing parking

facilities

in order to collect information about the use of existing parking facilities

in order to collect information about the information about the demand for

parking is needed.

Parking studies may be restricted to

A particular traffic producer or attractor, such as a store, or

They may encompass an entire region, such as a CBD.

Types of Parking Studies Inventory of Parking Facilities

Accumulation Counts

Duration and Turnover Surveys

User Information Surveys

Land Use Method of Determining Demand

Inventory of Parking FacilitiesInformation is collected on the current condition of parking facilities. This

includes:

the location, condition, type, and number of parking spaces.

parking rates if appropriate. These are often related to trip generation or

other land use considerations.

time limits, hours of availability and any other restrictions.

layout of spaces: geometry and other features such as crosswalks and city

services.

ownership of the off-street facilities.

Accumulation Counts These are conducted to obtain data on the number of vehicles

parked in a study area during a specific period of time.

First, the number of vehicles already in that area are counted or

estimated.

Then the number of vehicles entering and exiting during that

specified period are noted, and added or subtracted from the

accumulated number of vehicles.

Accumulation Counts Accumulation data are normally summarized by time period for

the entire study area.

The occupancy can be calculated by taking accumulation/total

spaces.

Peaking characteristics can be determined by graphing the

accumulation data by time of day.

The accumulation graph usually includes cumulative arrival and

cumulative departure graphs as well.

Accumulation CountsPeriod Arrive Cum. Arrive Depart Cum. Depart Accumulation Accumulation

Factor

4 – 6 AM 25 5

6 -8 50 15

8 – 10 250 25

10 – 12 Noon 50 30

12 – 2 PM 100 50

2 - 4 50 75

4 – 6 25 220

6 – 8 25 100

8 - 10 10 65

Total 585 585

Accumulation Counts

Period Arrive Cum. Arrive Depart Cum. Depart Accumulation Accumulation Factor

4 – 6 AM 25 25 5 5 20 0.0341

6 -8 50 75 15 20 55 0.0940

8 – 10 250 325 25 45 280 0.4786

10 – 12 Noon 50 375 30 75 300 0.5128

12 – 2 PM 100 475 50 125 350 0.5982

2 - 4 50 525 75 200 325 0.5585

4 – 6 25 550 220 420 130 0.2222

6 – 8 25 575 100 520 55 0.0940

8 - 10 10 585 65 585 0 0

Total 585 585

Accumulation Counts

0 1 2 3 4 5 6 7 8 9 100

100

200

300

400

500

600

700

Accumulation Diagram

Cum. Arrive

Cum. Depart

Accumulation

Time

vehicles

Accumulation Counts Accumulation data are normally summarized by time period for

the entire study area.

The occupancy can be calculated by taking accumulation/total

spaces.

Peaking characteristics can be determined by graphing the

accumulation data by time of day.

The accumulation graph usually includes cumulative arrival and

cumulative departure graphs as well.

Duration and Turnover SurveysThe accumulation study does not provide information on

parking duration

turnover or

parking violations

This information requires a license plate survey, which is often

very expensive. Instead, modifications are often made to the

field data collection protocols.

Duration and Turnover Surveys In planning a license plate survey, assume that each

patrolling observer can check about four spaces per minute.

The first observer will be slower, because all the license plate

numbers will have to be recorded, but subsequent observers

will be able to work much faster. The form shown below can

be used for a license plate survey.

Duration and Turnover SurveysTypical License Plate Survey Field Form

Street Side Study Date

Data Collector _________________________________________

From ___________________

To: _________________ Direction of Travel:

Stall Type Time at beginning of Patrol

8:00 8:30 9:00 9:30 10:00

User Information Surveys Individual users can provide valuable information that is not

attainable with license plate surveys.

The two major methods for collecting these data are

parking interviews and

postcard studies

For the parking interviews, drivers are interviewed right in the

parking lot. The interviews can gather information about origin

and destination, trip purpose, and trip frequency.

User Information/Characteristics Surveys The postage paid postcard surveys requests the same

information as in the parking interview. Return rates average

about 35%, and may include bias.

The bias can take two forms. Drivers will sometimes overestimate

their parking needs in order to encourage the surveyors to

recommend additional parking.

Or, they may file false reports that they feel are more socially

acceptable.

User Information/Characteristics Surveys

User characteristics analyses are made to assist in parking management in an area.

Such studies are used in establishing time-limit parking, employee parking, loading

zones, etc.

Information is obtained on the magnitude of the various segments of the parking

demand.

In other words, the study is used to project the demand for short-term parking (15 to

20 minutes); for banks, pharmacies, dry cleaners, etc.; for limited parking ( 1 to 2

hours) covering short-term shopping or business appointments; for longer term

parking (8 hours or ore) for employees in the area.

Land Use Method of Determining Demand

Parking generation rates can be used to estimate the demand for parking.

Tabulate the type and intensity of land uses throughout the study area.

Based on reported parking generation rates, estimate the number of

parking spaces needed for each unit of land use.

Determine the demand for parking from questionnaires. A rule of thumb is

to overestimate the demand for parking by about 10%. If the analysis

suggests that the parking demand for a particular facility will be 500

spaces, then the design should be for 550 spaces.

Parking Measurement and Analyses There are four major indices describing the parking utilization

of the area or site of focus.

Occupancy (%) = 100 *

Accumulation = number of vehicles parked at a given time

Turnover = number of vehicles utilizing the same stall over a

given period of time (4 or more during an 8-h period indicates a

high turnover rate)

Average duration = =

Adequacy Analysis The adequacy of a parking facility can be measured by

calculating the probability that an entering vehicle will not be

able to find a parking space.

A high probability of rejection (not finding a space) may indicate

that expansion of the parking facility is warranted.

The probability of rejection can be calculated by comparing the

traffic load to the number of parking stalls as shown below.

Adequacy AnalysisFirst, the traffic load is estimated using:

A = Q*T

Where:

A = traffic load,

Q = incoming vehicle flow rate, and

T = the average parking duration

Adequacy AnalysisNext, calculate the probability of rejection using the following formula:

P = (AM/M!)/(1 + A + A2/2 + . . . + AM/M!)

Where:

P = the probability of rejection,

A = the traffic load, and

M = the number of parking stalls.

If the probability of rejection is high, you may want to consider adding more parking stalls to

the parking facility.

Example Over the course of an 8-hour day, 96 vehicles enter a local

electronics store’s parking lot. The parking lot has 5 spaces

and the average customer stays in the grocery store for 15

minutes. Calculate the probability that an incoming car will be

rejected.

Solutioni. Calculate the incoming flow rate:

Q = 96 vehicles/ 8 hours

Q = 12 vehicles/hour

Since we know the average vehicle is parked for 15 minutes, or 0.25 hours, we can

calculate the traffic load as follows.

A = Q*T

A = 12 vehicles/hour * 0.25 hours

A = 3 vehicle

Solutionii.  Find the probability of rejection using the equation below.

P = (AM/M!)/(1 + A + A2/2 + . . . + AM/M!)

Where:

P = the probability of rejection,

A = the traffic load, and

M = the number of parking stalls.

P = (35/120)/(1 + 3 + 32/2 + 33/6 + 34/24 +35/120)

P = 0.11

Each entering vehicle has an 11% chance of being rejected. As a result, the electronics

store loses one out of each 10 customers entering their lot.

Key Terms Aisle-- the portion of the parking lot devoted to providing immediate

access to the parking stalls. The recommended aisle width is dependent

on the parking angle. A parking angle of 45 o requires an aisle width of 12

feet for a 9.0-foot stall, and a 90o parking angle requires an aisle width of

26 feet for a 9.0-foot stall. These dimensions lead to wall to wall distances

of 47 feet for 45o and 63 feet for 90o.

Parking turnover is the rate of use of a facility. It is determined by

dividing the number of available parking spaces into the number of

vehicles parked in those spaces in a stated time period.

Key Terms Long Term Parking-- parking with a duration of three hours or

more.

Short Term Parking-- parking with a duration of three hours or less.

Parking Accumulation-- the total number of vehicles parked in a

specific area (usually segregated by type of parking facility) at a

specific time.

Parking Space or Stall-- an area large enough to accommodate

one parked vehicle with unrestricted access (no blockage by

another parked vehicle). Stall Length-- The longitudinal dimension of the stall, normally 18.5

feet. Stall Width-- The width of each parking space as measured

crosswise to the vehicle. The most common width is 8.5 to 9.0 feet.

Lecture 4:

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