Preliminary test method for the determination of surface firmness.

The Americans with Disabilities Act Accessibility Guidelines (ADAAG) specify that ground and floor surfaces should be firm, stable, and slip-resistant. These specifications are subjective; objective methods for assessing surface firmness and stability are lacking. Objective measures are needed to assess the accessibility of walking and wheeling surfaces and to improve accessibility for people with mobility limitations. This research study focused only on the development of an objective wheelchair work measurement method to assess surface firmness. Firmness was quantified in terms of the work per meter required to propel a wheelchair across the surface. Work was determined by using a SMARTwheel to measure the forces applied to the pushrim. This measurement method was evaluated on carpet, hard trail surfaces, and various playground surfacing materials. Measurements were also taken on an adjustable ramp set at different grades, cross slopes, and grade/cross slope combinations. Reliable results were obtained on all test surfaces except two (sand and pea gravel) which could not be negotiated by the test wheelchair rider according to the test protocol. The test method was capable of measuring a wide range of surface types, produced repeatable results on nearly all test surfaces, and was sensitive enough to measure 1% changes in grade and differences in surfacing materials. Comparisons between the measurements made on level surfaces and on various ramp angles demonstrated the feasibility of using the work per meter value for a specific ramp grade as pass/fail performance criteria for short distances of accessible surfaces. For outdoor recreational environments, this work measurement method would provide an objective measure of firmness which could be used to classify surfaces into categories (e.g., hard, firm, soft).