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ADA 2010 Standards

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705 Detectable Warnings

705.1 General. Detectable warnings shall consist of a surface of truncated domes and shall comply with 705.

705.1.1 Dome Size. Truncated domes in a detectable warning surface shall have a base diameter of 0.9 inch (23 mm) minimum and 1.4 inches (36 mm) maximum, a top diameter of 50 percent of the base diameter minimum to 65 percent of the base diameter maximum, and a height of 0.2 inch (5.1 mm).

705.1.2 Dome Spacing. Truncated domes in a detectable warning surface shall have a center-to-center spacing of 1.6 inches (41 mm) minimum and 2.4 inches (61 mm) maximum, and a base-to-base spacing of 0.65 inch (17 mm) minimum, measured between the most adjacent domes on a square grid.

705.1.3 Contrast. Detectable warning surfaces shall contrast visually with adjacent walking surfaces either light-on-dark, or dark-on-light.

Figure (a) is an enlarged elevation drawing of a single dome showing the base diameter as 0.9 to 1.4 inches (23 to 36 mm) and the top surface as having a diameter of 50% to 65% of the bas.  The dome height is 0.2 inch (5.1 mm).  Figure (b) is a plan view of a detectable warning surface showing the center-to-center dome spacing of 1.6 to 2.4 inches (41 to 61 mm) with a base-to-base separation of 0.65 inch (17 mm) minimum.  

Figure 705.1 Size and Spacing of Truncated Domes

705.2 Platform Edges. Detectable warning surfaces at platform boarding edges shall be 24 inches (610 mm) wide and shall extend the full length of the public use areas of the platform.