Figure 8 contains two line drawing perspectives demonstrating the effects of excessive sidewalk
cross slopethat is the slope of the sidewalk across its width, perpendicular to the line of travel
on pedestrians who use wheelchairs. In downhill travel, the forces of gravity tend to pull the
wheelchair towards the curb. The pushing forces required to counteract these effects will be
different on each wheelrim--small on the high side and large on the low side of the sidewalk.
Forward momentum toward the curb may require unequal hand braking on the wheels, leading to
a possible loss of control and balance. In wet or icy conditions, the pedestrian in a wheelchair
may slide toward and over the curb.
In uphill travel, extra effort is required to overcome the cross slope force, effort that might otherwise be used to climb the slope. Icy or wet conditions underfoot may lead to a rearward slide, also toward the curb.
|Figure 7 | Figure 9|