Accessible Exterior Surfaces Technical Article

CONCLUSIONS

The results of this pilot study suggest:

• Surfaces that can be objectively measured as firm and stable generally require less energy, are perceived as less strenuous, allow higher ambulation velocities, and are perceived as less difficult to walk on.

• Ambulation tends to be more difficult (i.e., increased energy consumption, higher ratings of perceived exertion, higher levels of difficulty ratings and decreased velocity) on wood chips (CPBR), engineered wood fiber J (EWFJ), and engineered wood fiber K (EWFK) surfaces.

• Sand (SAND) is the most difficult surface for all user groups, but the difference is particularly dramatic for those using a manual wheelchair.

• Ambulatory subjects with mobility limitations (with and without assistive devices) have higher energy costs on the surfaces that are objectively measured as firm and stable, which may explain in part why their energy costs had a relatively smaller increase on the surfaces that were not objectively measured as firm and stable.

• There is some indication, even with the limited number of subjects in this study, that the softness of a surface can improve the comfort of walking on the surface when using prosthetic technologies. For the same reason that people prefer to run on non-paved surfaces, some users would find walking on non-paved surfaces more comfortable as well.

• The low energy costs for manual wheelchair users on surfaces that were objectively measured as firm and stable increase dramatically on the surfaces that were not measured as firm or stable.

• Community mobility of the subjects as measured by total energy expenditure on the ADAAG course, level of fitness as measured by the PWC170 and grip strength tests, and the type of mobility limitation were significantly related to the “accessibility” of the surfaces (i.e., subjects who had difficulty ambulating in an ADAAG-compliant environment also found it more difficult to ambulate on surfaces that were not objectively measured as firm and stable).

• Energy expenditure increases for ambulation with turns relative to ambulation on a straight course. Further investigation would be required to understand the impact of the type of mobility limitation (particularly for the ambulatory groups), the specific type of disability, and the specific type of assistive device used.

• All subject testing was conducted on surfaces under dry conditions. Conclusions for these types of surfaces under wet conditions could be inferred from the results of objective measurement methods under “wet” conditions.

• Path fines and dirt were significantly less firm and stable under wet conditions. Increased energy expenditure would be expected on these surfaces in a wet condition for people who have increased levels of energy expenditures on less firm and stable surfaces.

• The Wheelchair Work Measurement Method provides reliable measures of the work required to propel a wheelchair across a level surface. However, the test equipment is not portable, and measurements are unreliable on sloped surfaces. Therefore, it is not suitable as a standard test method for exterior surfaces.

• The Rotational Penetrometer test procedure has been proven to provide consistent and repeatable objective measures of both firmness and stability on a full spectrum of surfaces, ranging from very hard and stable to very soft and unstable (i.e., concrete to sand).

• The Rotational Penetrometer is easy to use, portable, provides repeatable results on surfaces that are level within 5%, and is capable of measuring surfaces under both wet and dry conditions.

• Measurements obtained with the Rotational Penetrometer correlated with the results of the Wheelchair Work Measurement Method. They also correlated with the level of difficulty ratings and measures of energy consumption for subjects walking on a variety of surfaces.