There is some confusing language in the old ADAAG and the Texas Accessibility Standards regarding passenger loading zones. The words are the same in both documents (emphasis added):
Passenger Loading Zones. Passenger loading zones shall provide an access aisle at least 60 in (1525 mm) wide and 20 ft (240 in)(6100 mm) long adjacent and parallel to the vehicle pull-up space (see Fig. 10). If there are curbs between the access aisle and the vehicle pull-up space, then a curb ramp complying with 4.7 shall be provided. Vehicle standing spaces and access aisles shall be level with surface slopes not exceeding 1:50 (2%) in all directions.
This would seem to permit a layout like this…..
There are a couple of problems with this layout: (1) The access aisle is required to be level, which means that the curb ramp may not be within the access aisle; and (2) the curb ramp is in a location that can be blocked by parked vehicles.
The revised ADA/ABA Guidelines is very specific about the relationship of the vehicle pull-up space and the access aisle:
503.3 Access Aisle. Passenger loading zones shall provide access aisles complying with 503 adjacent to the vehicle pull-up space. Access aisles shall adjoin an accessible route and shall not overlap the vehicular way.
503.4 Floor and Ground Surfaces. Vehicle pull-up spaces and access aisles serving them shall comply with 302. Access aisles shall be at the same level as the vehicle pull-up space they serve. Changes in level are not permitted.
They removed the confusing language about curbs and are specific that the vehicle pull-up space and the access aisle must be at the same level. This is really the only way to build an accessible passenger loading zone.