Bicycle Railing Height Report - AASHTO - Subcommittee on Design

DETERMINATION OF APPROPRIATE RAILING HEIGHTS FOR BICYCLISTS
NCHRP 20-7 (168)
Results of the Literature Review
Literature relevant to appropriate railing heights for bicyclists is limited. As such,
research and communication with committee members involved in the adoption of
<strong>AASHTO</strong> bicycle railing height guidelines was performed. This effort determined that
no scientific analysis was conducted to warrant the degree of safety of a 1.1-meter (42-
inch) versus a 1.4-meter (54-inch) railing height. The lack of available <strong>AASHTO</strong>
Committee meeting minutes and documentation outlining the adoption process creates a
challenge for researchers. Due to the lack of empirical data, supplemental resources were
consulted to aid in the determination of an appropriate railing height for bicyclists. The
supplemental resources included documents on bridge design aesthetics, dimensions of
the human body, center of gravity issues, and bicycle crash data.
Several resources discuss the effects of inappropriately introducing a man-made object,
such as a railing, into the foreground of a scenic view. Affected parties include
bicyclists, motorists, and residents of the surrounding area. The Federal Highway
Administration (FHWA) recommends conducting a visual impact analysis (VIA) to study
the change in continuity of a scenic view due to the introduction of a man-made object.
Visual transparency was also identified as an important factor in railing design
guidelines.
Other research material identified the importance of context sensitive design and studying
the surrounding landscape when implementing a bridge project. Good design and
engineering judgment should be used to blend the bridge into the landscape in all
environments. Recommendations include maximizing the view from the bridge through
flexibility in railing design. The design should take into consideration the varying
amount of time required for bicyclists to cross the bridge. Chapter 5 provides a moredetailed
summary of aesthetics and railing design.
Additional resources listed average heights of adult males and females and children,
including eye-level heights of motorists, and heights of bicyclists and pedestrians. These
heights help determine the ability to see over a railing along a bikeway or traffic barrier
within mountainous terrain. Chapter 3, “The Design Bicyclist,” summarizes human
dimensions and provides center-of-gravity analyses.
The literature review revealed that bicycle crash data involving railings is not a widelyreported
event. Crash surveillance systems and informational guides were investigated,
including the National Center for Statistics and Analysis (NCSA) Fatality Analysis
<strong>Report</strong>ing System (FARS), North Carolina Department of Transportation’s Division of
<strong>Bicycle</strong> and Pedestrian Transportation <strong>Bicycle</strong> and Pedestrian Crash Web-database, and
the FHWA “<strong>Bicycle</strong> Crash Types Information Guide.” Chapter 5 discusses the
limitations of available crash data in greater detail.
To supplement the literature review, a bicycle railing height survey was provided to state
bicycle coordinators, bicycle advocates, and bridge engineers. The survey questioned
respondents regarding railing height practices, and solicited information regarding crash
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