Figure 20 is a line drawing plan of a sidewalk corner with two perpendicular-type curb ramps.
Both curb ramps are noted as incorrectly oriented, since they are not perpendicular to the curbs
they cut through but are skewed to be parallellthat is, in line--with the crosswalks. Thus each
curb ramp has one long and one short side and the top and bottom edges are not parallel to each
other. The difficulties of using ramps such as these are demonstrated by 2 pedestrians using
wheelchairs. If the curb ramp is entered so that both casters start up the ramp at the same time,
then it will be necessary to make a turn on the ramp while ascending, which is difficult. If one
caster enters before the other, then the wheelchair will be unstable, with one caster off the ground.