Bicycle Railing Height Report - AASHTO - Subcommittee on Design

Chapter 1 - Introduction
DETERMINATION OF APPROPRIATE RAILING HEIGHTS FOR BICYCLISTS
NCHRP 20-7 (168)
Background
The land characteristics and environment surrounding a traveling surface can pose
hazards to users. Specific hazardous conditions consist of bodies of water, steep dropoffs,
or hazardous terrain adjacent to roadways, sidewalks, bikeways, or bridges. To
protect motorists, bicyclists, and pedestrians, railings are often installed along the
traveling surface.
The identification of these and other hazardous conditions adjacent to travel surfaces
influenced a collective consensus among highway officials to develop national railing
height guidelines and specifications. Various railing height recommendations were
subsequently established for multiple users, including motorists, bicyclists, and
pedestrians. However, professionals in the transportation field never reached a common
determination regarding the most appropriate railing heights for all users.
This study focuses on railings along shared use paths and bridges. A bikeway is defined
as a road, path, or way that is specifically designated (in some manner) as being open to
bicycle travel. Bikeways can consist of paths that are exclusively designated for bicycle
travel only, or roads that allow both vehicles and bicycles (i.e., shared-use facility). A
bridge is defined as a structure that allows people or vehicles to cross an obstacle, such as
a river, canal, or railway.
The American Association of State Highway Transportation Officials (<strong>AASHTO</strong>) is at
the forefront of adopting an appropriate railing height for bicyclists. <strong>AASHTO</strong>’s goal is
to foster the development, operation, and maintenance of an integrated national
transportation system. To accomplish this goal, <strong>AASHTO</strong> established several
committees to provide a forum for consideration of transportation issues. The Standing
Committee on Highways oversees the <strong>Subcommittee</strong> on Bridges and Structures and the
Highway <strong>Subcommittee</strong> on Design. The <strong>Subcommittee</strong> on Bridges and Structures
developed the <strong>AASHTO</strong> “Bridge Specifications,” while the Highway <strong>Subcommittee</strong> on
Design developed the “Guide for the Development of <strong>Bicycle</strong> Facilities.”
Currently, the <strong>AASHTO</strong> “Bridge Specifications” require a 1.4-meter (54-inch) bicycle
railing height 1 on bridges. Alternatively, the current <strong>AASHTO</strong> “Guide for the
Development of <strong>Bicycle</strong> Facilities” specifies a minimum bicycle railing height of 1.1
meters (42 inches) on bridges, which is consistent with the height required for pedestrian
railings. The difference in recommended railing heights is a point of discrepancy
between bicycle facility designers and bridge designers. Many bicycle facility designers
prefer the lower height, while bridge designers feel they must specify the higher height to
adequately protect the public. The higher height involves higher costs, requires
additional hardware, and impacts the view and sight distance. However, no empirical
data exists to support the selection of either height for bicycle railing.
1 <strong>Railing</strong> height consists of the distance from the travel surface to the top of the railing.
1