Assessment of Detectable Warning Devices for Specification Compliance orEquivalent Facilitation

摘要

The report evaluates the Americans with Disabilities Act Accessibility Guidelines(ADAAG) specification for detectable warnings and the applicability of equivalent facilitation to the development of detectable warning devices. Ambiguities in the specification are identified and solutions are recommended to address these problems. Detectable warnings are intended to aid the visually imparied to detect the presence of hazards on a circulation path. Transit authorities and manufacturers developing detectable warnings for use at rail platforms have requested assistance in interpreting the specification. Lack of precision in the specification language allows different interpretations, resulting in products that vary widely in their designs. The evolution of the detectable warning specification and the human performance considerations that led to changes in the specification are discussed. Recommendations are given for clarifying the language and eliminating the ambiguity in the specification. For transportation authorities unable to comply with the ADA detectable warning specification, the guidelines provide an alternative mechanism by which accessibility requirements may be met. Equivalent Facilitation permits the use of alternative designs provided they give equal or better access. The implications of departures from the specification are discussed and several tests are suggested for determining whether an alternative design meets the equivalent facilitation criterion.