Characteristics of Emerging Road and Trail Users and Their Safety

Path Width

AASHTO (pp. 35-36) recommends a minimum path width of 3 m (10 ft), notwithstanding the procedures given in the Highway Capacity Manual for calculating the number and effects of passing events.⁽²⁶⁾ The AASHTO recommendation does not explicitly account for user volumes and passing hindrance resulting from user encounters. AASHTO recommends a greater width if there is a substantial use by a mix of users. In a few instances, a lower width may be adequate.

Section 4.2.1 of the ADAAG requires a minimum clear width of 0.815 m (32 inches) at a point, and 0.915 m (36 inches) continuously, for single wheelchair passage. All of the "solo" manual and power wheelchair users (i.e., not accompanied by a dog or pulling another wheelchair) had sweep widths of 0.69 m (27 inches) or less, and would therefore be accommodated by ADAAG.

In addition, Section 4.2.2 of the ADAAG requires that the minimum width for two wheelchairs to pass is 1.525 m (60 inches). This assumes that both wheelchair users are traveling in parallel paths to each other and to the edges of the path.

With respect to sweep width, the critical user is the inline skater. With 85^th percentile sweep widths of 1.51 m (4.96 ft), two individuals passing in opposite directions would only just fit a 3m (10-foot) wide path. Additionally, this research only addressed individual users. Users traveling abreast in pairs or groups would likely require additional space. Examples of these include parents and children together, a wheelchair user with his/her dog, and a runner who is visually impaired with a lead.

Several user types, including bicycles, recumbent bicycles, and hand cycles, required more than 3 m (10 ft) of width (at the 85^th percentile level) to execute a three-point turn. Hand cyclists are the critical users, requiring 5.40 m (17.8 ft) (at the 85^th percentile level) to perform a three-point turn and not having other options for completing a shorter radius turn.

^26. Transportation Research Board. Highway Capacity Manual 2000. Transportation Research Board, National Academy of Sciences, Washington, DC, 2000.