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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 hieght of 0.2 inch (51 mm).
705.1.2 Dome Spacing -
Truncated domes in a detectable warning surface shall have a cent-to-center spacing of 1.6 inches (41 mm) minimum and a 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.
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.