Here’s what Wayne Stuart wrote: The State of California requires that I provide a contrasting color warning surface, but I can’t find the light reflectance value (LVR) of typical grey concrete as referenced in:
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.
- 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 visually with adjacent walking surfaces. Contrast in percent shall be determined by:
Contrast percent = [(B1-B2)/B1] x 100 where
- B1 = light reflectance value (LRV) of the lighter area and
- B2 = light reflectance value (LRV) of the darker area.
As far as I can tell, this requirement became effective on July 1. If you have any guidance, e-mail firstname.lastname@example.org. Tell Wayne I sent you.
Thank you! And don't forget to submit your entry for our 2015 Polished Concrete Award.