Parking Lot Layout Dimensions 9'-0' stall width (8'-0' for 30° and 0°)
n	S	A	C	U	S'	U'	Spaces per 100ft. of tree	Paved surface per space (sq. ft.)
90°	19'-0'	24'-0'	9'-0'	62'-0'	19'-0'	62'-0'	11.1	279
60°	21'-0'	18'-0'	10'-5'	60'-0'	18'-9'	55'-6'	9.6	313
45°	19'-0'	13'-0'	12'-9'	52'-8'	16'-7'	46'-2'	7.8	338
30°	16'-6'	11'-0'	16'-0'	44'-0'	13'-1'	37'-2'	6.3	349
0°	8'-0'	12'-0'	23'-0'	28'-0'	9'-0'	30'-0'	4.3	326

Parking areas take on many configurations. Parking spaces may be parallel, perpendicular, or angled (30, 45, or 60 degree) to the driving lane, or aisle. A common factor among these various parking layouts is the size of the parking space. The minimum standard automobile parking space should be 6 meters long and 2.75 meters wide. Individual parking stalls should be a minimum of nine feet by nineteen feet (9′ x 19′). However, special sections with slightly smaller stalls may be designated for compact cars to better utilize the area. Two-way traffic lanes have a minimum width of twenty-four feet (24′) and perimeter circulation road lanes should be thirty feet (30′).

A survey made by the Eno Foundation (Parking Lot Operation), showed that the aisle widths of eight parking lots with one-way aisles averaged 14 feet, and ranged from 7.5 to 21 feet. The low figure of 7.5 is amazing when you consider that the largest 1947 car was over 6 feet, 10 inches wide. Compute the paved area required for parking by multiplying the required number of stalls by the estimated land area per stall. As an example, a 200-space parking lot that is estimated to require 325 square feet per stall will need a paved area of 65,000 square feet, or about 1.5 acres. The dimensions of a bike vary by model. In general, most typical bikes will take up a bike parking spot of 30' x 72' x 48' when parked. For the footprint of bikes parked at a horizontal bike rack, additional space will need to be added to the dimensions of the bike.

Slot Hole Dimension

ADA Accessible Parking Space Requirements
Total number of parking spaces provided	Total minimum number of accessible parking spaces (5-foot and 8-foot aisles)	Total van accessible parking spaces with min. 8-foot access aisle	Total additional accessible parking spaces with min. 5-foot access aisle
1 to 25	1	1	0
26 to 50	2	1	1
51 to 75	3	1	2
76 to 100	4	1	3
101 to 150	5	1	4
151 to 200	6	1	5
201 to 300	7	1	6
301 to 400	8	1	7
401 to 500	9	2	7
501 to 1,000	2% of total parking provided	12.5% of 2nd column	87.5% of 2nd column
1,001 and over	20 plus 1% of total parking provided over 1,000 spaces	12.5% of 2nd column	87.5% of 2nd column

Tractor Trailer Parking Space Requirements
Description	Dimension
Parking space length	50 feet	15 meters
Parking space width	9 feet	2.75 meters
Outside turning radii	60 feet	18 meters
Vertical clearance	14 feet	4.25 meters
Backing and maneuvering area	50 feet	15 meters
Loading dock width	10 feet	3 meters
Loading dock height	4 feet	1.2 meters
Loading dock area	2x area of truck bed

Parking Stall Layout Considerations

The objective of the layout design is to maximize the number of stalls, while following the guidelines below.

• The layout of the parking facility must be flexible enough to adapt to future changes in vehicle dimensions.
• The stall and aisle dimensions must be compatible with the type of operation planned for the facility.

The critical dimensions are the width and length of stalls, the width of aisles, the angle of parking, and the radius of turns. All of these dimensions are related to the vehicle dimensions and performance characteristics. In recent years there have been a number of changes in vehicle dimensions. The popularity of minivans and sport utility vehicles has had an impact on the design of parking facilities. For the near future, a wide mix of vehicle sizes should be anticipated. There are three approaches for handling the layout:

1. Design all spaces for large-size vehicles (about 6 feet wide and 17-18 ft long).
2. Design some of the spaces for large vehicles and some for small vehicles (these are about 5 ft wide and 14-15 ft long).
3. Provide a layout with intermediate dimensions (too small for large vehicles and too big for small vehicles).
   

Standard Key Slot Dimensions

For design, it is customary to work with stalls and aisles in combinations called 'modules'. A complete module is one access aisle servicing a row of parking on each side of the aisle. The width of an aisle is usually 12 to 26 feet depending on the angle at which the parking stalls are oriented.

Stall Width

For simplicity, the stall width is measured perpendicular to the vehicle, not parallel to the aisle. If the stall is placed at an angle of less than 90^o, then the width parallel to the aisle will increase while the width perpendicular to the vehicle will remain the same.

Stall Length

The length of the stall should be large enough to accommodate most of the vehicles. The length of the stall refers to the longitudinal dimension of the stall. When the stall is rotated an angle of less than 90^o, the stall depth perpendicular to the aisle increases up to 1 foot or more. It should be noted that the effective stall depth depends on the boundary conditions of the module, which could include walls on each side of the module, curbs with or without overhang, or drive-in versus back-in operations. For parking at angles of less than 90^o, front bumper overhangs beyond the curbing are generally reduced with decreasing angle and, for example, drop to about 2 feet at 45^o angles. The Table 8-3 below gives the standard dimensions for several different layouts as defined by Figure 8-4.

Table 8-3 and Figure 8-4 where taken from:
Weant, R.A. and Levinson, H.S., Parking, Eno Foundation, 1990, page 161.

Interlock Module

A special type of module, the interlock, is possible at angles below 90^o. There are two types of interlock. The most common, and preferable, type is the bumper-to-bumper arrangement. The second type, the 'herringbone' interlock, can be used at 45^o and is produced by adjacent sides having one way movements in the same direction. This arrangement requires the bumper of one car to face the fender of another car. Figure 8-3 shows several different module layouts that are commonly used.

Comparing Angle Efficiencies

The relative efficiencies of various parking angles can be compared by looking at the number of square feet required per car space (including the prorated area of the access aisle and entrances). Where the size and shape of the tract is appropriate, both the 90^o and the 60^o parking layouts tend to require the smallest area per car space. In typical lot layouts for large size vehicles, the average overall area required (including cross aisles and entrances) ranges between 310 and 330 square feet/car. A very flat angle layout is significantly less efficient than other angles.

One-Way Aisles

There are many conditions where one-way aisles are desirable. With parking angles less than 90^o, drivers can be restricted to certain directions. However, the angle should usually be no greater than 75^o. Drivers may be tempted to enter the parking aisles and stalls from the wrong direction when the stall angle is too large. Adjacent aisles generally have opposite driving directions.