5.1 This practice provides a means for obtaining a quantitative estimate of a surface property defined as roughness using longitudinal profile measuring equipment.

5.1.1 The WPRI can be obtained from instruments which can capture high-resolution (described in X1.1.2) longitudinal profiles.

5.1.2 The WPRI is stable with time because true WPRI is based on the concept of a true longitudinal profile, rather than the physical properties of a particular type of instrument.

5.2 When profiles are measured simultaneously for multiple traveled wheel tracks, the MWPRI is a better measure of wheelchair pathway surface roughness than the WPRI for either individual wheel track.

5.3 Wheelchair pathway roughness data can be useful in determining the vibration exposure experienced by a wheelchair user. (See Fig. 1.)

FIG. 1 Wheelchair Pathway Roughness Index and Ratings

Note 1: The MWPRI scale is identical to the WPRI scale.

5.3.1 Vibration exposure has been linked to pain and injuries in wheelchair users and the WPRI of traveled surfaces provides the ability to quantify the vibration exposure a wheelchair user will experience when traveling that surface.4^,5

5.3.2 Knowledge of the vibration exposure a wheelchair user will experience on traveled surfaces will allow steps to be taken to minimize their exposure, reducing the likelihood of pain and injury.