2013 California Standards for Accessible Design Pocket Guide

11B-705.1.1.3 Color and Contrast.

Detectable warning surfaces at transit boarding platform edges, bus stops, hazardous vehicular areas, reflecting pools, and track crossings shall comply with Section 11B-705.1.1.3.1. Detectable warnings at other locations shall comply with either Section 11B-705.1.1.3.1 or Section 11B-705.1.1.3.2.  The material used to provide visual contrast shall be an integral part of the surface.

[2010 ADAS] 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-705.1.1.3.1.

Detectable warning surfaces shall be yellow and approximate FS 33538 of Federal Standard 595C.

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.