Operational Design Elements

The following excerpt was taken from the1992 edition of the Traffic Engineering Handbook, published by the Institute of Transportation Engineers (pp. 204-205).

The design of a parking facility is very strongly influenced by its intended operation. The basic design elements and their associated operational features may be identified in successive steps as follows:

1. Vehicular access from the street system (entry driveway);
2. Search for a parking stall (circulation and/or access aisles);
3. Maneuver space to enter the stall (access aisles);
4. Sufficient stall size to accommodate the vehicle’s length and width plus space to open car doors wide enough to enter and leave vehicle (stall dimensions);
5. Pedestrian access to and from the facility boundary (usually via the aisles) and vertically by stairs, escalators, or elevators in multilevel facilities;
6. Maneuver space to exit form the parking stall (access aisles);
7. Routing to leave facility (access and circulation aisles);
8. Vehicular egress to the street system (exit driveway); and
9. Any revenue-control system (may involve elements of entry, exit, or both).

The simplest form of off-street parking is a single stall at home. Assuming a straight driveway, steps 1 and 8 above use the same lane and curb cut, and step 9 does not apply. Steps 2 and 7 are rudimentary. Thus, a driveway serving a one-car parking stall or garage cannot be considered as representing a second parking space, if such parking would block continuous access to the basic stall. Step 6 usually involves backing out into the public street or alley, as part of steps 7 and 8. Herein lies the essential difference between low-volume parking and what generally should be practiced in facilities designed to handle more than a few cars. Except along alleys, the larger lots should have all parking and unparking maneuvers contained off-street. Frequent backing of cars across sidewalks and into public streets increases congestion and creates hazards.

For the large facilities, and particularly garages, an operational concept necessarily precedes structural, architectural, and other design elements. The concept begins with the question, "What do we plan to serve?" From answers to this question, design features emerge such as user ease of access, security, vehicle circulation and walk patterns, signing, lighting, and equipment needs.