2019 California Standards for Accessible Design Guide (effective January 1, 2020 with July 1, 2021 amendments)
11B-705.1 Detectable warnings
11B-705.1.1 General.
Detectable warnings shall consist of a surface of truncated domes and shall comply with Section 11B-705.
11B-705.1.1.1 Dome size.
Truncated domes in a detectable warning surface shall have a base diameter of 0.9 inch (22.9 mm) minimum and 0.92 inch (23.4 mm) maximum, a top diameter of 0.45 inch (11.4 mm) minimum and 0.47 inch (11.9 mm) maximum, and a height of 0.2 inch (5.1 mm).
[2010 ADA Standards] 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).
11B-705.1.1.2 Dome spacing.
Truncated domes in a detectable warning surface shall have a center-to-center spacing of 2.3 inches (58 mm) minimum and 2.4 inches (61 mm) maximum, and a base-to-base spacing of 0.65 inch (16.5 mm) minimum, measured between the most adjacent domes on a square grid.
[2010 ADA Standards] 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.
Exception: Where installed in a radial pattern, truncated domes shall have a center-to-center spacing of 1.6 inches (41 mm) minimum to 2.4 inches (61 mm) maximum.
(a) elevation (enlarged)
(b) plan
FIGURE 11B-705.1 SIZE AND SPACING OF TRUNCATED DOMES ‡‡
11B-705.1.1.3 Color and contrast. Detectable warning surfaces shall comply with Section 11B-705.1.1.3.1. The material used to comply with this section shall be an integral part of the detectable warning surface.
Exceptions:
1. Replacement of less than 20 percent of existing detectable warnings at a single contiguous location shall be permitted to be in-kind at existing curb ramps, islands, or cut-through medians with detectable warnings in compliance with the code requirements in effect at the time of installation.
2. Existing installed detectable warnings at curb ramps, islands, or cut-through medians may comply with Section 11B-705.1.1.3.2 in lieu of Section 11B-705.1.1.3.1.
11B-705.1.1.3.1.
Detectable warning surfaces shall be yellow and approximate 33538 of SAE AMS-STD-595A.
11B-705.1.1.3.2.
Detectable warning surfaces shall provide a 70 percent minimum visual contrast with adjacent walking surfaces. Contrast in percent shall be determined by:
Contrast percent = [(B1-B2)/B1] x 100 percent where
B1 = light reflectance value (LRV) of the lighter area and
B2 = light reflectance value (LRV) of the darker area.
[2010 ADA Standards] 705.1.3 Contrast. Detectable warning surfaces shall contrast visually with adjacent walking surfaces either light-on-dark, or dark-on-light.
Exception: Where the detectable warning surface does not provide a 70 percent minimum contrast with adjacent walking surfaces, a 1 inch (25 mm) wide minimum visually contrasting surface shall separate the detectable warning from adjacent walking surfaces. The visually contrasting surface shall contrast with both the detectable warning and adjacent walking surfaces either light-on-dark, or dark-on-light.
11B-705.1.1.4 Resiliency.
Detectable warning surfaces shall differ from adjoining surfaces in resiliency or sound-on-cane contact.
Exception: Detectable warning surfaces at curb ramps, islands or cut-through medians shall not be required to comply with Section 11B-705.1.1.4.
11B-705.1.2 Locations.
Detectable warnings at the following locations shall comply with Section 11B-705.1.
11B-705.1.2.1 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.
11B-705.1.2.2 Curb ramps.
Detectable warnings at curb ramps shall comply with Section 11B-705.1.2.2.
11B-705.1.2.2.1 Perpendicular curb ramps.
Detectable warnings at perpendicular curb ramps shall extend 36 inches (914 mm) in the direction of travel. Detectable warnings shall extend the full width of the ramp run less 2 inches (51 mm) maximum on each side, excluding any flared sides. Detectable warnings shall be located so the edge nearest the curb is 6 inches (152 mm) minimum and 8 inches (203 mm) maximum from the demarcation line at the face of the curb between the curb and the gutter, street or highway.
11B-705.1.2.2.2 Parallel curb ramps.
Detectable warnings at parallel curb ramps shall be located so the edge nearest the curb is 6 inches (152 mm) minimum and 8 inches (203 mm) maximum from the demarcation line at the face of the curb between the curb and the gutter, street or highway. Detectable warnings shall extend the full width of the turning space at the demarcation between the street and the sidewalk less 2 inches (sic) (51 mm) maximum on each side.
11B-705.1.2.2.2.1 One entrance/exit point.
Where the turning space has one entrance/exit point other than the sloped ramp segments, detectable warnings shall be 36 inches (914 mm) deep, as measured perpendicular to the curb, and the turning space shall provide a minimum 36 inches (914 mm) wide portion without detectable warnings to allow pedestrian travel in the direction of the sidewalk without travelling over the detectable warnings.
Exceptions:
1. Where it is technically infeasible to provide a minimum 72 inches (1828 mm) wide turning space, as measured perpendicular to the curb, the depth of detectable warnings may be reduced to 24 inches (610 mm) minimum.
2. Existing parallel curb ramps with detectable warnings in compliance with the code requirements in effect at the time of installation shall not be required to provide a minimum 36 inches (914 mm) wide portion of the turning space without detectable warnings.
FIGURE 11B-705.1.2.2.2
PARALLEL CURB RAMPS
11B-705.1.2.2.2.2 Two entrance/exit points.
Where the turning space has two entrance/exit points other than the sloped ramp segments, detectable warnings shall be 36 inches (914 mm) deep at both entrance/ exit points, as measured perpendicular to the curb, and the turning space shall provide a minimum 36 inches (914 mm) wide portion without detectable warnings to allow pedestrian travel in the direction of the sidewalk without travelling over the detectable warnings.
Exceptions:
1. Where it is technically infeasible to provide a minimum 108 inches (2743 mm) wide turning space, as measured perpendicular to the curb, the depth of detectable warnings may be reduced to 24 inches (610 mm) minimum.
2. Existing parallel curb ramps with detectable warnings in compliance with the code requirements in effect at the time of installation shall not be required to provide a minimum 36 inches (914 mm) wide portion of the turning space without detectable warnings.
FIGURE 11B-705.1.2.2.2
PARALLEL CURB RAMPS
11B-705.1.2.3 Islands or cut-through medians.
Detectable warnings at pedestrian islands or cut-through medians shall be 36 inches (914 mm) minimum in depth extending the full width of the pedestrian path or cut-through less 2 inches (51 mm) maximum on each side, placed at the edges of the pedestrian island or cut-through median, and shall be separated by 24 inches (610 mm) minimum of walking surface without detectable warnings.
Exception: Detectable warnings shall be 24 inches (610 mm) minimum in depth at pedestrian islands or cut-through medians that are less than 96 inches (2438 mm) in length in the direction of pedestrian travel.
11B-705.1.2.4 Bus stops.
When detectable warnings are provided at bus stop boarding and alighting areas, the detectable warnings shall extend the full width of the boarding/alighting area and shall be 36 inches (914 mm) minimum in depth.
11B-705.1.2.5 Blended transitions. Detectable warnings at blended transitions shall be 36 inches (914 mm) in width.
11B-705.1.2.6 Reflecting pools.
When detectable warnings are provided at reflecting pools, it shall be 24 inches (610 mm) minimum and 36 inches (914 mm) maximum in width.
11B-705.1.2.7 Track crossings.
Detectable warnings at track crossings shall be 36 inches (914 mm) in the direction of pedestrian travel and extend the full width of the circulation path.
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