Question 311149
ADA says a ramp can go up at most 1 foot for every 12 feet of horizontal distance.A ramp in San Francisco at the Hotel Nikko rises 5.6 inches over a horizontal span of 4'7". Is the ramp to code?Include, the maximum angle of elevation, the minimum ramp length for 12 feet of horizontal and 1 foot of rise. Please show all work.
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1 ft in 12 = 1 inch per foot = 1/12" rise per inch horizontal
4'7" = 71 inches
71*(1/12) = 5.912", the max allowed rise in that horizontal distance.
5.6" is less than that, so it's legal.
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The max angle is the arctan(1/12) =~ 4.76º
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The ramp length is the hypotenuse of the right triangle with legs of 1' and 12'
{{{s = sqrt(1+144) = 12.0416 feet, or 12' 0.449"
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Feet and inches are tedious and inconvenient compared to the metric system.