According to
US federal building codes, the
maximum height for an access ramp is 30 inches.
To reach entrances that exceed this limit, lifts or an
elevator may be installed.
Most cars cannot climb hills that have a
slope of 30° (or rise about 1 foot for
every 1.7 feet horizontally).
Most local building codes describe a maximum
stair rise of 81/4 inches and a minimum tread
width of 9 inches.
More than nine
out of ten avalanches occur on slopes ranging
from 25° to 45°.


The
ratio for slope is independent of units.
Most black diamond
ski slopes are around 30°
to 35°, while a 40° slope would be
considered the low end of extreme mountaineering.
Parts of Tuckerman’s Ravine on Mt. Washington
have slopes of about 50°.
Slopes are rates
of change, a fundamental idea of calculus.
Another way to express a slope uses the
trigonometry notion of tangent. 