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

3. Terminology

3.1 Definitions:

3.1.1 Terminology used in this practice conforms to the definitions included in Terminology E867.

3.1.1.1 longitudinal profile measurement, n—a series of elevation values taken at a constant interval along a wheel track.

3.1.1.1.1 Discussion—Elevation measurements may be taken statically, as with rod and level per Test Method E1364 or dynamically using a rolling inclinometer per Test Method E2133.

3.1.1.2 traveled surface roughness—the deviations of a surface from a true planar surface with characteristics dimensions that affect vehicle dynamics, ride quality, dynamic loads, and drainage, for example, longitudinal profile, transverse profile, and cross slope.

3.1.1.3 wave number, n—the inverse of wavelength.

3.1.1.3.1 Discussion—Wave number, sometimes called spatial frequency, typically has units of cycle/m or cycle/ft.

3.1.2 Definitions of Terms Specific to This Standard:

3.1.2.1 Pathway Roughness Index (PRI), n—an index computed from a longitudinal profile measurement using a standard 70 mm (2.5 in.) diameter wheel with no deformation and no affects from speed. The index will be a representation of the total vertical deflection of that wheel as it would travel over the surface.

3.1.2.1.1 Discussion—PRI is reported in either millimeters per meter (mm/m) or inches per foot (in./ft).

3.1.2.2 Mean Pathway Roughness Index (MPRI), n—the average of the PRI values for multiple trials

3.1.2.2.1 Discussion—Units are in millimeters per meter or inches per foot.

3.1.2.3 true Pathway Roughness Index, n—the value of PRI that would be computed for a longitudinal profile measurement with the constant interval approaching zero.

3.1.2.4 wheel path, n—a line or path followed by a non-deformable tire of a wheeled vehicle on a traveled surface as it approaches zero speed.