Truncated domes in a detectable warning surface shall have a base diameter of 0.9 inches
(23 mm) minimum to 1.4 inches
(36 mm) maximum, a top diameter of 50% of the base diameter minimum to 65% of the base diameter maximum, and a height of 0.2 inches
(5 mm)
Frank Synoground, October 24, 2002
I would like to offer the following comments on the draft regulations and thank the committee for its considerable efforts. I am blind and am particularly interested in tactile warnings.
Detectable Warnings (1104.3.2)
Detectable warnings should only be required where the ramp slope was 1:15
In reference to sections as cited below:
1108.1 General.
Detectable warnings shall consist of a surface of truncated domes aligned in a square grid pattern and shall comply with 1108.
1108.1.1 Dome Size.
Truncated domes in a detectable warning surface shall have a base diameter of 0.9 inches
The above listed specifications would seem to eliminate or at least not acknowledge parallel tactile warnings that would act as wayfinding as well as warning. I am blind and consider wayfinding in some cases an important safety issue as well.
Frank Synoground
Portland, OR