Characteristics of Emerging Road and Trail Users and Their Safety

Horizontal Alignment

The minimum clearance to an obstruction that should be provided along a horizontal curve is a function of the stopping sight distance and radius of the curve. The critical user for this dimension would be the inline skater. For example, using the 85^th percentile stopping distance, the minimum offset required for a 15.8-m (50-ft) radius curve would be 3.4 m (11 ft).

In contrast, the AASHTO minimum offset for a bicyclist with its presumed 38.7-m (127-ft) stopping sight distance is 10.7 m (35 ft). However, using the observed 85^th percentile stopping sight distance for bicyclists, 12.4 m (41 ft), yields a required length offset of only 1.3 m (4.1 ft).