R305 — Detectable Warning Surfaces

R305.1 General. Detectable warning surfaces shall consist of truncated domes in a square or radial grid pattern and shall comply with R305. R305.1.1 Dome Size. The truncated domes shall have a base diameter of 0.9 inches (23 mm) minimum and 1.4 inches (36 mm) maximum, a top diameter of 50 percent of the base diameter minimum and 65 percent of the base diameter maximum, and a height of 0.2 inches (5.1 mm). When detectable warning surface tiles are cut to fit, partial domes are permitted along the cut edges. R305.1.2 Dome Spacing. The truncated domes 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 inches (17 mm) minimum, measured between the most adjacent domes. Exceptions: 1. When detectable warning surfaces are cut to fit, center-to-center spacing measured between domes adjacent to cut edges shall not exceed twice the normal spacing between domes not adjacent to cut edges. 2. Dome spacing requirements do not apply at a gap in a detectable warning surface at an expansion joint provided that the detectable warning surface aligns with both edges of the expansion joint. R305.1.3 Contrast. Detectable warning surfaces shall contrast visually with adjacent walking surfaces, either light-on-dark or dark-on-light. R305.1.4 Surface Size. Detectable warning surfaces shall extend 24 inches (610 mm) minimum in the direction of pedestrian travel. The width of detectable warning surfaces shall be as follows: A. At curb ramps and blended transitions, detectable warning surfaces shall extend the full width of the curb ramp run (excluding any flared sides), blended transition, or landing. B. At cut-through pedestrian refuge islands, detectable warning surfaces shall extend the full width of the pedestrian circulation path opening. C. At pedestrian at-grade rail crossings not located within a street, detectable warning surfaces shall extend the full width of the pedestrian circulation path. D. Where required at boarding platforms, detectable warning surfaces shall extend the full length of the unprotected areas of the platform. E. At boarding and alighting areas at sidewalk or street level transit stops for rail vehicles, detectable warning surfaces shall extend the full length of the unprotected area of the transit stop. R305.2 Location. The location of detectable warning surfaces shall comply with R305.2. Where a concrete border is required for proper installation of a detectable warning surface, a concrete border not exceeding 2 inches (51 mm) shall be permitted on all sides of the detectable warning surface except between the detectable warning surface and the edge of pavement where a setback is already permitted. R305.2.1 Perpendicular Curb Ramps. On perpendicular curb ramps, detectable warning surfaces shall be located as follows: A. Where the ends of the bottom grade break are in front of the back of curb or at the edge of pavement where there is no curb, the detectable warning surface shall be placed at the back of curb or no greater than 6 inches (150 mm) from the edge of pavement where there is no curb. B. Where the ends of the bottom grade break are behind the back of curb or edge of pavement where there is no curb and the distance from both ends of the bottom grade break to the back of curb or edge of pavement where there is no curb is 60 inches (1525 mm) or less, the detectable warning surface shall be placed on the ramp run at the bottom grade break. C. Where the ends of the bottom grade break are behind the back of curb or edge of pavement where there is no curb and the distance from either end of the bottom grade break to the back of curb or edge of pavement where there is no curb is more than 60 inches (1525 mm), the detectable warning surface shall be placed on the clear area so that both front corners of the detectable warning surfaces are at the back of curb or no greater than 6 inches (150 mm) from the edge of pavement where there is no curb. R305.2.2 Parallel Curb Ramps. On parallel curb ramps, detectable warning surfaces shall be located on the landing at either the back of curb or the edge of pavement where there is no curb. R305.2.3 Blended Transitions. On blended transitions, detectable warning surfaces shall be located on the blended transition so that both front corners of the detectable warning surfaces are at the back of curb or no greater than 6 inches (150 mm) from the edge pavement where there is no curb. R305.2.4 Pedestrian Refuge Islands. At cut-through pedestrian refuge islands, detectable warning surfaces shall be located no greater than 6 inches (150 mm) from the edges of the pedestrian refuge island or at back of curb and shall be separated by a 24 inch (610 mm) minimum length of surface in the direction of travel without detectable warning surfaces. R305.2.5 Pedestrian At-Grade Rail Crossings. At pedestrian at-grade rail crossings not located within a street, detectable warning surfaces shall be located on each side of the rail crossing. The edge of the detectable warning surface nearest the rail crossing shall be 6 feet (1.8 m) minimum and 15 feet (4.6 m) maximum from the centerline of the nearest rail. Where pedestrian gates are provided, detectable warning surfaces shall be located on the side of the gate opposite the rail. Pedestrian gates shall not overlap detectable warning surfaces. R305.2.6 Boarding Platforms. At boarding platforms for transit vehicles, detectable warning surfaces shall be located at the boarding edge of the platform. Exception: Where a curb is present at the boarding edge of the platform, the detectable warning surface may be placed at the back of curb. R305.2.7 Sidewalk and Street-Level Rail Boarding and Alighting Areas. At boarding and alighting areas at sidewalk or street-level transit stops for rail vehicles, detectable warning surfaces shall be located at the edge of the boarding and alighting area closest to the rail vehicles. R305.2.8 Driveways. Where driveways are controlled with yield or stop control devices or traffic signals, detectable warning surfaces shall be provided on the pedestrian circulation path where the pedestrian circulation path meets the driveway.