Development of Surface Roughness Standards for Pathways Used by Wheelchair Users: Final Report

4. Summary of Practice

4.1 This practice was developed specifically for estimating pathway roughness from longitudinal profile measurements.

4.2 Longitudinal profile measurements for one wheel track are transformed mathematically by a computer program and accumulated to obtain the PRI. The profile must be represented as a series of elevation values taken along with a series of horizontal distance values along the wheel track.

4.3 The PRI scale starts at zero for a surface with no roughness and covers positive numbers that increase in proportion to roughness. Figure 1 provides PRI value descriptors from research conducted at the Human Engineering Research Laboratories for simulated and community surfaces made of wood, segmental paving units, cast-in-place concrete, and asphalt.