ADA parking space and access aisle layout

Choose the space and aisle configuration

Accessible parking is a connected layout: vehicle space, access aisle, accessible route, entrance, and required signs. The ADA Standards set a typical minimum width of 96 inches for a car space and 132 inches for a van space. A van space may instead be 96 inches wide when paired with a 96-inch-wide access aisle. The access aisle serving either space is generally at least 60 inches wide, runs the full length of the space, and can be shared by two adjacent spaces. Confirm the required number and distribution of accessible spaces under the applicable scoping rules.

When parking spaces are angled, orient the access aisle so a person using a ramp or lift can deploy it without entering another parked vehicle’s space. Angled van spaces have specific passenger-side aisle requirements. Aisles cannot overlap the vehicular way. Coordinate striping, wheel stops, curbs, columns, and signs so the measured usable dimensions remain after construction. The Standards measure widths to the centerline of markings when spaces or aisles are striped next to one another, so line thickness should not be used to reduce clear width.

Keep the aisle level and connected

Parking spaces and access aisles must have stable, firm, slip-resistant surfaces and meet the floor and ground surface criteria. The aisle is at the same level as the space it serves, with slopes no steeper than 1:48 permitted for drainage. Built-up curb ramps cannot project into the space or aisle because they create excessive slope and interfere with vehicle transfer. If a curb separates the aisle from an accessible route, place the curb ramp outside the aisle and protect the level transfer area.

The aisle must adjoin an accessible route to an accessible entrance. Trace that route on the site plan across sidewalks, drive lanes, gates, and grade changes. A space can have all the correct striping and still fail as a usable parking location if the aisle ends at a curb, loading zone, landscape bed, or inaccessible door. Where the route crosses vehicle traffic, the Access Board recommends a clearly marked crossing where appropriate and, where possible, avoiding a path behind parked vehicles.

Van clearance and vertical obstructions

Van-accessible spaces, the access aisles serving them, and the vehicular routes serving those spaces need at least 98 inches of vertical clearance. Check canopies, beams, signs, sprinkler piping, garage equipment, tree branches, and overhead doors. The clearance needs to cover the vehicle route into the space as well as the space and aisle; a clear stall below a low beam does not solve a low approach route. Include vertical clearance dimensions in garage plans and coordinate them with structural and mechanical systems.

The required number of van spaces and their distribution depends on the facility and applicable scoping provisions. Mark spaces with signs and pavement markings in accordance with federal and state/local requirements. The ADA Standards require accessible parking signs to be mounted so the bottom edge is at least 60 inches above the ground, subject to specified exceptions. Local rules may set sign design, colors, additional wording, or penalties; check the jurisdiction’s requirements in addition to ADA dimensions.

Mark the aisle so it stays available

Access aisles must be marked to discourage parking in them. The ADA Standards do not prescribe a single marking color or pattern, but state or local codes may. Mark the full length so drivers understand the area is not another parking stall. Keep bollards, sign posts, wheel stops, and protective posts out of the usable aisle unless a specific design maintains the required clear width. A stripe layout that looks wide on paper can narrow after posts and curbs are installed.

Access aisle location depends on the space arrangement. Aisles may be placed on either side of a standard accessible space, and two spaces may share an aisle. For angled van parking, the aisle must be on the passenger side. Verify that sharing an aisle does not place a column, sign post, or curb ramp in the center. Keep the route and aisle clear of snow storage, deliveries, carts, and construction staging after turnover.

Coordinate grading and drainage

The 1:48 maximum slope in any direction is a tight grading limit. The civil plan should show spot elevations at corners of spaces and aisles, transitions, curb ramps, and adjacent accessible route. Surface water should drain without creating a cross-slope or ponding. A trench patch, asphalt overlay, settlement, or concrete lip can change the finished slope and create a level change. Survey the built condition after paving rather than relying only on design contours.

Transitions between the aisle and the route should not introduce an abrupt level change. Drainage inlets and utility covers need to be coordinated so grates do not block the route or create an unstable surface. If the accessible route passes behind parked cars, consider the risk of vehicle overhang and backing movements. The layout should provide a direct, legible route to the entrance with curb ramps aligned to the crossing direction.

Example: review a van space in a garage

A plan calls for a 96-inch van space beside a 60-inch aisle. That combination does not meet the optional narrow-space alternative, which requires a 96-inch aisle. The layout can be revised to a 132-inch space with a 60-inch aisle, or retained at 96 inches with the aisle widened to 96 inches. The reviewer then checks the full-length aisle, passenger-side location if angled, 98-inch overhead clearance along the space and route, marking, 1:48 maximum slope, route to the entrance, and signage. Each piece is necessary for the intended van access.