Bicycle Railing Height Report - AASHTO - Subcommittee on Design

DETERMINATION OF APPROPRIATE RAILING HEIGHTS FOR BICYCLISTS
NCHRP 20-7 (168)
The top railing of a bicycle railing should be rigid. A steel mesh or tension cable system
that replaces the intermediate rails may be considered to allow a more transparent look,
as illustrated in Figures 15 and 16.
Figure 15 - Tension Cable <strong>Railing</strong>
Figure 16 - Steel Mesh <strong>Railing</strong>
If the height of a railing is a serious consideration in the obstruction of a view, the top
railing can be lowered by adding an extended top rail at a retracted angle on the outside
of the railing, thus maintaining the effective height of the railing. This type of railing has
been specified for the Clinton River Trail Master Plan in Michigan, and is illustrated in
Figure 17. 14 If a bicyclist were to rotate over the top rail, the extended rail would restrain
the center of gravity. The “effective” height in Figure 17 is a sum of the height of the
railing and the extended railing, which totals 1.4 meters (54 inches).
The design of the bottom rail is another important consideration. One of the crashes
reported in the survey involved a bicyclist losing control and sliding under the railing. A
railing system should have adequate bottom protection to prevent a fallen bicyclist from
sliding underneath the railing.
Another important consideration is the location of railings relative to the path of travel.
<strong>AASHTO</strong> “Guidelines for <strong>Bicycle</strong> Facilities” recommends that, “a minimum 0.6-m (2-
foot) wide graded area with a maximum 1:6 slope be maintained adjacent to both sides of
the path; however, 0.9 m (3 feet) or more is desirable to provide clearance from trees,
poles, walls, fences, guardrails or other lateral obstructions.” 15 <strong>Bicycle</strong> railings are
frequently placed too close to the travel path, thereby reducing the effective width of the
path. Bicyclists will tend to “shy” away from the railing, which increases the risk of a
collision with another path user.
14 The Greenway Collaborative, Inc. “Clinton River Trail Master Plan, Michigan.” November 2003.
15 <strong>AASHTO</strong>. “Guide for the Development of <strong>Bicycle</strong> Facilities,” 1999.
37