Truncated Dome Effective Warning Systems

The truncated dome is a kind of detectable warning system installed on roads, curb ramps and other hazardous areas to enable safe movement for visually impaired people. Most detectable warning systems make use of textural differences or bold contrast in colors to warn those with limited or impaired vision of dangerous zones which require special care or assistance to navigate. The Americans with Disabilities Act has lad down certain guidelines to be followed when constructing commercial and public facilities

Intersections where vehicles and people come into close interaction are complex environments especially for those with impaired or limited vision. To travel safely and independently such people rely on environmental cues such as curbs, texture changes underfoot, ambient sounds and other physical elements that can be sensed with a cane. In such case detectable warning systems as that provide by truncated dome surfaces go a long way in enabling safe and independent travel for visually impaired people.

In 1990 the Americans with Disabilities Act was passed and next year the U.S Department of Transportation and the U.S. Department of Justice developed a set of regulations for new construction and alterations. These regulations followed recommendations from U.S Access Board which is an independent federal agency devoted to promoting accessibility for people with disabilities. The guidelines laid down that detectable warning systems like truncated dome surfaces be installed on sidewalks, street crossings, curb ramps, hazardous vehicular routes and transit platform edges.

A detectable warning system such as the truncated dome surface is a texturally unique and standardized feature intended to function in the same way as a stop sign does for general traffic. Such features are built in or applied to walking surfaces and other elements so that the visually impaired pedestrians are alerted to the presence of danger in the line of travel. The warning system requires them to stop and determine the nature of the hazard before proceeding further.

The truncated dome has been functioning as the standard design requirement in detectable warning systems ever since 1991. The small flattened dome provides a surface that is distinguishable underfoot and by cane. Moreover they are closely spaced so that pedestrians can maintain stability and the color of the dome also contrasts with the surrounding pedestrian ramp to alert low-vision persons to imminent traffic dangers.
Research conducted by the U.S. Access Board in the 1980s showed that other warning designs such as grooves, striations and exposed aggregate are not immediately detectable in the roadside environment because of similarities to other surface textures and defects.

A truncated dome surface on the other hand provides a distinctive pattern which is easily capable of being detected by cane and underfoot. There are mainly three types truncated warning domes – inset, glued and stamped. Currently the guidelines for public rights-of-way in the United States, published in June 2002, describe detectable warnings as a surface of truncated domes arranged in a square grid pattern. Tfhrc