You are assuming that the only reason someone in a wheelchair might have to go between the sidewalk and the street is to access a crosswalk to cross the street. That is an incorrect assumption.<p>Vehicles that carry wheelchairs often load and unload the wheelchair from the street in the rear of the vehicle. Ramps in the middle of the street help people in wheelchairs to enter and leave such vehicles without having to go all the way to a crosswalk.