The Effects of Truncated Dome Detectable Warnings on Travelers Negotiating Curb Ramps in Wheelchairs

Abstract: Truncated domes on curb ramps benefit travelers with visual impairments. However, concerns associated with the safety and negotiability of such detectable warnings for other travelers have resulted in much controversy. The findings of the study presented here indicate that detectable warnings did not adversely affect the negotiability of ramps by the 21 participants who ambulated by wheelchairs. ********** The Architectural Barriers Act and the Rehabilitation Act of 1973 are key laws that ensure access to public facilities and public rights-of-way by all persons, including those who have disabilities. Physical barriers that prevent individuals with disabilities from gaining access to public facilities are prohibited by law. Because of these laws, such environmental and architectural barriers are occasionally removed to enable individuals with disabilities to more about in the community with increased mobility. The design of buildings, sidewalks, roadways, and vehicles can have a great impact on the mobility of individuals and their ability to access community services and events. The basic concept of universal design is that the built environment should accommodate a wide spectrum of potential users (Stratton, 2001) and not hinder anyone (such as someone with a disability). True universal design can be cost effective and can benefit individuals of all ages and abilities. Curb ramps are perhaps the most common example of universal (or accessible) design because they were designed for individuals who use wheelchairs but are also beneficial for others, such as people with shopping carts or strollers, bicyclists, and workers with utility carts. The curb ramp may be the most important design consideration for individuals who use wheelchairs (Florida Pedestrian Planning and Design Handbook, 1999). Although the installation of ramps benefits individuals with mobility impairments, the absence of curbs results in the loss of information that individuals with visual impairments (that is, those who are blind or have low vision) often use to detect streets (Barlow & Bentzen, 1994; Hauger, Rigby, Safewright, & McAuley, 1996). Consequently, some pedestrians with visual impairments have difficulty locating the boundary between the sidewalk and road, particularly when the slope of the ramp is gradual. Thus, detectable warnings were developed to alert travelers who are visually impaired to potential hazards and vehicular pathways. A detectable warning is "a standardized surface feature built in or applied to walking surfaces or other elements to warn people who are blind or visually impaired of specified hazards" (Public Rights-of-Way Access Advisory Committee, 2001, PROWAAC, p. 5). The only surface that has repeatedly been demonstrated to be detectable to most pedestrians with visual impairments is the truncated dome detectable warning surface. The vast majority of research on detectable warning surfaces has been on the effects of these surfaces on individuals with visual impairments. Research initially focused on identifying surface materials and textures for walking surfaces that would be highly detectable to travelers with visual impairments. The U.S. Access Board published the Americans with Disabilities Act Accessibility Guidelines (ADAAG) in 1991, which the U.S. Department of Justice adopted as the ADA Standard for Accessible Design. Research has suggested that other designs, such as grooves, striations, and exposed aggregate, should not be considered for use because of their similarity to other surface textures in the built environment. Current standards for the dimensions and pattern of detectable warnings are based on research that was conducted in the late 1980s and was subsequently required by the ADA to be installed at all transit stations (Mitchell, 1988; Peck & Bentzen, 1987). The Access Board (2006) stated that the truncated dome is the most reliable surface for detection by cane and underfoot (Bentzen, Nolin, Easton, Desmarais, & Mitchell, 1994; Hauger et al. …