Guide for the Development of Bicycle Facilities - The Industrialized ...

guide for development of bicycle facilities 39
However, when a lean angle of 20 o is used, more horizontal space will
be taken up by the bicyclist taking the curve and more width needs to be
provided. In these cases the pathway width should be increased and a
center line placed down the middle of the path.
When curve radii smaller than those shown in Table 2 must be used because
of limited right-of-way, topographical features or other
considerations, standard curve warning signs and supplemental pavement
markings should be installed in accordance with the MUTCD 2 .
The negative effects of sharper curves can also be partially offset by widening
the pavement through the curves.
Grade
Grades on shared use paths should be kept to a minimum, especially on
long inclines. Grades greater than 5 percent are undesirable because the
ascents are difficult for many bicyclists to climb and the descents cause
some bicyclists to exceed the speeds at which they are competent or
comfortable. On some shared use paths, where terrain dictates, designers
may need to exceed the 5 percent grade recommended for bicycles
for some short sections. As a general guide, the following grade restrictions
and grade lengths are suggested:*
5-6% for up to 240 m (800 ft)
7% for up to 120 m (400 ft)
8% for up to 90 m (300 ft)
9% for up to 60 m (200 ft)
10% for up to 30 m (100 ft)
11+% for up to 15 m (50 ft)
Grades steeper than 3 percent may not be practical for shared use paths
with crushed stone or other unpaved surfaces for both handling and
drainage erosion reasons.
Options to mitigate excessive grades:
❍ When using a longer grade, an additional 1.2-1.8 m (4-6 feet) of
width to permit slower speed bicyclists to dismount and walk may
be considered.
❍ Provide signing that alerts bicyclists to the maximum percent of
grade (MUTCD 2 ).
❍ Provide recommended descent speed signing.
❍ Exceed minimum stopping sight distances.
❍ Exceed minimum horizontal clearances, recovery area and/or protective
bike rails.
*See Chapter 2—Other Design Considerations, Accessibility Requirements, p. 69.
Design
Shared Use Paths