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Parking Lot Design: Glossary

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Accessible Path-- a barrier-free path that persons with mobility or sensory impairments can safely follow without obstacles or obstructions. Accessible paths are at least 5 feet wide and level.

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.

CBD-- Central Business District, typically ranging from an average size of 27 blocks (10,000-25,000 population cities) to over 200 blocks (cities over 1,000,000 population).

CBD Core-- the heart of business, commercial, financial and administrative activity. Typically ranges in size from an average of 7 blocks (10,000-25,000 population cities) to over 60 blocks (cities over 1,000,000 population).

CBD Fringe-- the area immediately surrounding the CBD, usually within 2-3 blocks.

Change of Mode-- the transfer from one form of transportation to another. A park and ride lot is an example of a change of mode, where an auto driver parks the vehicle and rides public transportation for the remainder of the trip.

Cordon Count-- the simultaneous counting of all traffic entering and leaving a given area such as a CBD. It is generally a manual vehicle classification count, supplemented with automatic traffic recorder counts.

Duration-- the length of time a vehicle remains in one parking space.

Long Term Parking-- parking with a duration of three hours or more.

Module-- a complete module is one access aisle, servicing a row of parking on each side of the aisle. Both the access aisle and the parking stalls serviced by that aisle are part of the module.

Outlying Business District-- commercial area generally removed by a mile or more from a central CBD.

Parking Accumulation-- the total number of vehicles parked in a specific area (usually segregated by type of parking facility) at a specific time.

Parking Demand-- the number of vehicles with drivers desiring to park at a specific location or in a general area. It is usually expressed as the number of vehicles during the peak-parking hour.

Parking Space or Stall-- an area large enough to accommodate one parked vehicle with unrestricted access (no blockage by another parked vehicle).

Parking Supply-- the number of spaces available for use, usually classified by on-street curb (metered and unmetered), lot and garage. Further differentiation of the types of parking is useful, such as those available to the general public, and private spaces earmarked for a specific purpose such as loading.

Parking Volume-- the total number of vehicles that park in a study area during a specific length of time.

Partial Module-- one access aisle combined with a single one-side row of parking.

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

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.

Study Period-- the time during which the parking study is conducted, usually between 10:00 A.M. and 6:00 P.M. Increasing emphasis, however, is being placed on inclusion of the morning and evening periods within the length of the study. Certain uses, such a theatres, may peak in the evening hours, while residential parking demand peaks around 3:00 A.M.

Trip Purpose-- the primary reason for the individual’s journey to the study area. Typical purposes include shopping, working, business, and recreation.

Turning Radii-- The radius of the circle that is traveled by the design vehicle when completing a turn. Large turning radii should be provided. These are a function of the parking angle and end island design, but in general the turning radii should be at least 18 feet.

Turnover-- the number of different vehicles parked at a specific parking space or facility during the study period. Parking turnover measures utilization.

Van Accessible-- a parking space that is at least 8 feet wide, with a minimum access aisle of 5 feet along the right side of the parking space.