The WA State DOT's Standard Plans specify yellow for detectable warnings (truncated domes). While the ADAAG (4.29)does not specify color, it does require a light-on-dark, dark-on-light contrast. The contrast must be enough to be discernible to those with low vision (i.e., white is not a good choice unless the surrounding ramp is considerably darker). Many entities use the 70% contrast formula suggested in the ADAAG (A4.29.2), as it appears to provide enough of a contrast to distinguish the walking surface of the curb ramp from the roadway surface.

This city uses RED as the color for various reasons. We also install colored concrete in the pedestrian path in the street in new construction . Asphalt does pose different challenges that we encounter infrequently, mostly on trails.

Florida uses the 'basic' yellow, red & black, depending on the situation and location. Some districts prefer one color over another. We also use the 70% contrast ratio recommended by ADAAG when determining which color to use.

When the new ADAAG is the law of the land will there be a criterion established to help quantify light-on-dark, dark-on-light, such as the 70% formula in A4.29.2?

My understanding from speaking with the Access Board is that the 70% contrast formula was a misapplication of a retroreflectivity requirement from sign sheeting. I also understand that that there is no reliable way to measure the values in the existing formula in the field, that it is a laboratory test not suited to sidewalk color contrast. The use of yellow is also more problematic than most of us realize. Yellow is highly discernable under daylight conditions, but not so under low-light conditions. At night it may look the same color as concrete; sodium-vapor lighting would make it look white. Blue has better nighttime visibility.

But, Blue is difficult/impossible to see for some persons with low vision. My understanding is that blue should NOT be used for detectable warnings as it doesn't provide an appropriate visual cue for persons with low vision. High contrast or yellow are the perferred colors.

Chicago uses Bindan Corporation's BRICK RED precast detectable warningtile as the standard throughout the city.

At ndot the product vendors are responsible for providing a product that meets the applicable specifications. The only time that a certain color is specified would be for aesthetic purposes, such as in a historic district, redevelopment area or other masterplanned area with certain color requirements.

You do not try and keep the color uniform through out your applications?

The short version is we are going to start. The long version is that when the Access Board did not extend the suspension and I began the detectable warning implementation process our aesthetics section did not have an opinion on the matter. Lacking any input from local or federal sources I only required that the same color be used throughout the project. After reading the comments here, however, I revisited the issue with our current Landscape Architect and there is now an opinion on the need for a uniform color that will work with our statewide landscape master plan palettes and generally blend in well with local streetscapes. As of yesterday I will begin modifying our requirements to specify a dark on light (concrete sidewalk/ramp)color range of DE-5117 to DE-5118 and a light on dark (asphalt path/ramp) color range of DE-6255 to DE-6256. The designations are from the Dunn-Edwards color palette. These colors are generally compatible with the color shades chosen through public workshops held around the state as part of the aesthetics master plan corridor studies.

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