Bicycle Railing Height Report - AASHTO - Subcommittee on Design

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DETERMINATION OF APPROPRIATE RAILING HEIGHTS FOR BICYCLISTS NCHRP 20-7 (168) highway rail. A smooth termination or transition should be provided to reduce the possibility of the vehicle “goring” onto the end of the rail. The railing should also be smooth on the structure, with no protruding materials that could potentially snag the vehicle during a collision. Pedestrian and <strong>Bicycle</strong> <strong>Railing</strong> Design The 2002 <strong>AASHTO</strong> “Standard Specifications for Highway Bridges” has imposed more stringent requirements for railing height. Section 2.7.2.2.1 of the specifications states, “The minimum height of a railing used to protect a bicyclist shall be 54-inches, measured from the top of the surface on which the bicycle rides to the top of the top rail.” Section 2.7.3.2.1 states, “The minimum height of a pedestrian railing shall be 42-inches measured from the top of the walkway to the top of the upper rail member.” s opposed to the “Guide for the Development of <strong>Bicycle</strong> Facilities,” the “Standard Specifications for Highway Bridges” and “LRFD Bridge Design Specifications” use the word “shall” instead of “should” when specifying the minimum height requirement for bicycle and pedestrian railing (1.4 meters (54 inches) and 1.1 meters (42 inches) respectively). The use of the word “shall” signifies that the heights represent requirements rather than design guidelines. The 1989 <strong>AASHTO</strong> “Guide Specification for Bridge <strong>Railing</strong>” also requires a height of 1.4 meters (54 inches) for bicycle railing and a height of 1.1 meters (42 inches) for pedestrian railing. Section G2.7.2.2.1 states, “The minimum height of a railing used to protect a bicyclist shall be 54 inches, measured from the top of the surface on which the bicycle rides to the top of the top rail.” Additionally, Section G2.7.3.2.1 states, “The minimum height of a Figure 3 - Golden Gate Bridge <strong>Railing</strong>s Source: John Allen. pedestrian railing shall be 3 feet 6 inches measured from the top of the walkway to the top of the upper rail member.” The use of the word “shall” signifies that the heights represent requirements rather than design guidelines. According to the guide specification, the design of the rail shall include “consideration to safety, appearance, and freedom of view.” These considerations are similar to those in the Standard Specification for Highway Bridges, with the latter providing more detail: “when the bridge carries mixed traffic freedom of view from passing vehicles.” 9
DETERMINATION OF APPROPRIATE RAILING HEIGHTS FOR BICYCLISTS NCHRP 20-7 (168) Both specifications indicate that the critical requirement for bicycle railing is providing a height that protects the bicyclist. Aesthetics and providing a view from the travel lanes represent secondary requirements. The project engineer can use his/her discretion when meeting these last two requirements. The height specifications for pedestrian and bicycle railings are consistent with the <strong>AASHTO</strong> “LRFD Bridge Design Specifications.” Requirements also exist that limit the size of the openings between horizontal and vertical elements. In accordance with the “LRFD Bridge Design Specifications,” the requirements prevent objects from falling or being pushed through the railing onto the travel way below. Section 2.7.2.2 of the 2002 “Standard Specifications for Highway Bridges,” which supercedes all other bridge guidelines, states “Within a band bordered by the bikeway surface and a line 27 inches above it, all elements of the railing assembly shall be spaced such that a 6-inch sphere will not pass through any opening. Within a band bordered by lines 27 and 54-inches, elements shall be spaced such that an 8-inch sphere will not pass through any opening.” <strong>AASHTO</strong> Guidelines for the Development of <strong>Bicycle</strong> Facilities The 1999 <strong>AASHTO</strong> “Guide for the Development of <strong>Bicycle</strong> Facilities” addresses three conditions where railings should be installed. The conditions include: structures (i.e., bridges), two-way shared-use paths adjacent to a roadway, and shared-use paths adjacent to slopes and/or waterways. The “Guide for the Development of <strong>Bicycle</strong> Facilities” was not intended to set forth strict standards, but to provide sound guidelines for the planning and design of bicycle facilities. As such, planners, engineers, and designers will not find the word “shall” when reviewing the recommendations for designing bicycle facilities. The word “shall” implies a mandatory condition. Traditionally, when certain requirements in design or application are described with the word “shall,” it is mandatory that these requirements be met. Conversely, the word “should” is used when certain design or application recommendations are intended for guidance or directional purposes. Chapter 2 of the 1999 <strong>AASHTO</strong> bicycle guide states, “<strong>Railing</strong>s, fences or barriers on both sides of a path on a structure should be a minimum of 1.1 meters (42 inches) high.” The chapter provides no guidance regarding the conditions adjacent to the structure, such as the distance of the dropoffs. It is assumed that every 1.1-m(42-in) Figure 4 - <strong>Bicycle</strong> <strong>Railing</strong> - 1.1 Meter High <strong>Railing</strong> Crossings of Colonie Park, Town of Colonie, New York 10
Page 1 and 2: NCHRP NATIONAL COOPERATIVE HIGHWAY
Page 3 and 4: DETERMINATION OF APPROPRIATE RAILIN
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Page 53 and 54: BICYCLE RAILING HEIGHT SURVEY STATE
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BICYCLE RAILING HEIGHT SURVEY STATE
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BICYCLE RAILING HEIGHT SURVEY ADVOC
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2-6. What was the serverity of the
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APPENDIX B
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Bicycle Railing Height Report - AASHTO - Subcommittee on Design

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