36 CFR Part 1190, Proposed Accessibility Guidelines for Pedestrian Facilities in the Public Right-of-Way: Notice of Proposed Rulemaking (NPRM)

R406.3 Unobstructed Side Reach. Where a clear space allows a parallel approach to an element and the side reach is unobstructed, the high side reach shall be 1220 mm (4.0 ft) maximum and the low side reach shall be 380 mm (1.25 ft) minimum above the finish surface. An obstruction shall be permitted between the clear space and the element where the depth of the obstruction is 255 mm (10 in) maximum.