Proposed Surface Roughness Standard for Pathways used by Wheelchairs

摘要

Over two million people in the United States use a wheelchair for their primary means ofmobility and rely on functional and accessible sidewalks to participate in their communities. TheAmericans with Disabilities Act Accessibility Guidelines (ADAAG) related to roughness aresubjective and not measurable which results in public pathways with many bumps and crackswhich can lead to harmful whole-body vibrations (WBVs) for wheelchair users. ISO standard2631-1 specifies health guidance caution zones for how much vibration exposure can bedangerous, but it is unknown how surface roughness can affect the amount of vibrations thatwheelchair users are exposed to. To develop a standard for surface roughness, subjective ratingsand RMS accelerations were gathered and analyzed from subjects traveling over surfaces withvarious roughnesses in their own wheelchairs. As expected, the results show that as surfaceroughness increased, RMS accelerations increased and subjective ratings decreased. Somesurfaces generated RMS accelerations above the ISO health guidance zone and/or were rated asunacceptable by more than half of the subjects suggesting that some surfaces are causing harmfulvibrations and discomfort to wheelchair users. Based on the combination of RMS data andsubjective feedback from wheelchair users, we are proposing a roughness index threshold of 1.20in/ft for a 5m moving average window, and 0.60 in/ft for a 100m moving average window. Thisproposal will allow for small “transition” rough areas such as detectible warning pads atcrosswalks but will restrict the roughness of the overall long surface or city block.