705.1-2 – Detectable Warnings

705.1 General.

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

705.1.2 Dome Spacing.
Truncated domes in a detectable warning surface shall have a center-to-center spacing of 41 mm (1.6″) minimum and 61 mm (2.4″) maximum, and a base-to-base spacing of 17 mm (2/3″) 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 (610mm) wide and shall extend the full length of the public use areas of the platform.