Whenever I read 'wheelchair' in a script my rolling-light goes on. Usually the wheelchair will be in action on camera. As a result, often I find myself drafting up a set with a practical ramp.
Depending on the Production Designer, this can bring up some tricky set design issues. Not all PD's are well rehearsed in architectural standards, as they come from all walks of life. Some were Interior Designers, some were Graphic Artists etc. The good PD's are aware of their deficiencies, after all, who knows about everything? They hire people who can fill in the gaps for them, thereby building a solid team. They listen to their set designers, whose job it is to look the data up, and explain to the PD that his/her design must be reconfigured due to the wheelchair ramp requiring a lineal length of 38 feet.
The wheelchair ramp grade can be found in the stairs & ramps chart in any Graphic Standards book.