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14. Parking Design

14.1 Introduction

The provision of adequate parking facilities is an essential part of the design and construction of transport infrastructure.

Provision for parking may conveniently be thought of in three categories:

on road parking (kerbside or centre-of-the-road);
off road single level; and
off road multi-level.

Whichever type of facility is to be provided it will be necessary to design for a specific size of vehicle, with certain manoeuvring characteristics. A ‘design vehicle’ must therefore be established as part of the design process.

Geometric design standards for parking facilities should take into account not only the operational disadvantages of under-design but also the financial disadvantages of over-design. In some sections of parking design standards lower than the ideal can be tolerated. Sections of parking facilities can be divided into two categories – critical areas and non-critical areas. Non-critical areas will usually be designed to satisfy about 85% of common vehicles and hence the 85 percentile design vehicle is used. Critical areas must be designed to cater for all vehicles (or, economically, nearly all vehicles) so that a 99 percentile design vehicle is used.

14.2 Design Vehicles

The recommended minimum dimensions for design purposes are the dimension just allowing movement by the appropriate design vehicle plus a clearance around the vehicle. Austroads in its publication "Guide to Traffic Engineering Practice" gives the following guide dimensions of a design vehicle for on-street parking:

Guide Dimensions for a Design Vehicle for Kerbside Parking
Description	Dimension (m) 85 percentile	Dimension (m) 99 percentile
Overall length	4.74	5.37
Overall width	1.86	1.89
Front overhang	0.813	0.996
Rear overhang	1.100	1.300

14.3 Kerbside Parking

The major purpose of a road is to provide for the safe and free movement of road traffic. Another function of many roads is to allow vehicles to park at the kerbside to allow the access of people to adjacent properties. However, the act of parking or unparking can interfere with the free flow of vehicles in the adjacent lane. In addition parked vehicles contribute to pedestrian accidents with persons entering the roadway between or behind parked vehicles. The use of kerbside space on streets to accommodate stationary vehicles therefore should be regulated to provide the optimum conditions for all road users considering safety for motorists and pedestrians, vehicle flow, and the need for on-street parking to serve adjacent properties.

Angle parking is more convenient than parallel parking but it invariably produces a much higher accident rate than parallel parking at the same location. Angle parking is not adaptable to commercial vehicles and requires substantially larger street widths. The angle parking manoeuvre is easier to accomplish and causes less interference to traffic than the parallel parking manoeuvre, but the unparking manoeuvre is not as easily executed. Other disadvantages are that motorists drive more slowly when looking for vacant spaces and the car’s overhang at the kerb is greater interfering with pedestrians, awning posts, and signs on the footway. Angle parking accommodates more cars for a given length of kerb than parallel parking.

The decision on the type of parking allowed in any street must be based on:

the width of road;
the volume and type of traffic;
the turnover expected;
the nature of neighbourhood; and
the road classification.

Taxi stands should be distributed at convenient locations for patrons throughout business centres. Stands should normally be restricted to accommodate no more than four taxis at a time. If the demand is greater the main taxi stand should be fed from feeder stands established nearby. The length of a taxi stand should be (5.5n + 1.5) metres where n is the number of taxis to be accommodated.

Although some establishments provide off-street loading and unloading bays, most loading and unloading takes place at the kerb and provision for loading zones must be made. The length of loading zones can vary greatly depending on the number and type of establishments served by each zone and the usual type of vehicles using the zone. The recommended minimum length is 9 m.

14.4 Centre-of-the-Road Parking

This type of parking can only be considered for very wide streets and should be avoided unless adequate provision is made to separate through traffic from parked vehicles, motorists looking for spaces, and vehicles parking or unparking. One disadvantage is that pedestrians leaving and returning to their vehicles have to cross the main traffic stream to reach the footway.

Where vehicles have direct access to parking spaces from main traffic lanes they may cause unnecessary interference with through traffic, reduce the traffic flow, and produce a greater proportion of accidents.

14.5 Off-Street Parking

Off-street parking requirements normally depend on the extent and type of development in the area, and the availability of on-street parking spaces.

The design problem for off-street parking areas is basically one of layout of parking spaces, both to maximise the number of parking spaces and also to facilitate circulation and access to those spaces. Layouts usually involve either angle or perpendicular parking. Parallel parking is rarely used, except perhaps at the boundaries of the area where insufficient space may remain to allow any alternative arrangement.

The majority of car parks in Australia are constructed with 90° parking because it produces the most efficient layout in most cases.

Design for efficient circulation of vehicles within a parking lot should aim at ease of movement around the site and safety for both vehicles and pedestrians. A definite circulation plan should be developed, taking into account the different activities which occur at the site; for example, the design for a supermarket parking area should allow for pedestrian movements, parcel pickup, deliveries, etc.

Site entry and exit is always an important component of the design. The location of entry and exit points depends not only on conditions and activities within the site, but perhaps even more importantly on interactions with traffic on the road or roads adjacent to the site. In some instances it will be more efficient to combine entry and exit at the one location, while in other cases internal circulation and external traffic considerations will indicate that separate entrances and exits should be provided. Allowance for adequate queue storage space is another issue associated with entry and exit, especially the avoidance of queues extending into the street at entrances.

Special problems may have to be considered in the design of parking areas for public facilities such as sports arenas and concert halls, which have very large demands concentrated over short periods. Circulation and entry/exit design must aim for maximum efficiency to enable rapid evacuation of the parking area as the conclusion of the event attended by the parkers.

14.6 Multi-Level Carparks

Multi-level car parks concentrate a high number of parking spaces into a small area, and also have the potential to concentrate parking problems within the area. However, in some respects they are simpler to design than single level car parks because heavy vehicles and buses are usually excluded from their operation. Also the circulation system for vehicles is often simpler. Multi-level car parks are normally only proposed in areas of high density development where it is economical to construct a multistorey structure rather than to acquire land for single level parking.

The special problems associated with multi-level car parks can be summarised as follows:

Presence of columns in the structure, which restricts access to parking spaces and which may inhibit door opening of vehicles.
The geometry and grades of ramps between parking levels.
The concentration of queuing and circulation problems at the level or levels at which entry and exit take place.
The often long driving paths to a vacant space encouraging operating speeds higher than those desirable.
Provision of ticketing and pay facilities.

14.7 Operation of Off-Street Parking Facilities

Many off-street parking facilities are open to the public free of charge and provide for each driver to park his or her own vehicle. These are usually surface lots and may be provided by municipalities, retail complexes, etc. Such facilities require almost no administration or control once they are established, apart from periodical maintenance and, in some municipal car parks, the same enforcement of parking duration limits as is necessary for on-street parking.

A significant proportion of off-street parking facilities, however, do not fall into the above category and their method of operation depends upon whether self-parking or attendant parking is to be used and involves the administration of parking fees.

LINK TO THE PICTURE GALLERY

The Picture Gallery contains photographs relating to Carparks .

LINKS TO SITES ON PARKING

The International Parking Institute in the USA has some useful and interesting information at their Web site. The Frequently Asked Questions section mentions that there are an estimated 105 million parking spaces in the USA, that there is estimated to be 5 million parking meters worldwide, and that the New York City gains revenue of $300 million per annum from parking related fines!

Brisbane City have information on Carparking within the City. Some people that park in Brisbane are not aware that in the Central Traffic Area (the Central Business District and surrounding areas) the parking time limit is 2 hours, even if the parking space is not designated with a time limit.

Page last modified 25 June 2002.