Bicycle Safety Guide and Countermeasure Selection System


Example of shared-use path between two highway bridges. - Margaret Gibbs

Illustration from Oregon Bicycle and Pedestrian Design Guide, Oregon DOT Ramp allowing bicycle access to sidewalk on bridge.
Illustration from Oregon Bicycle and Pedestrian Design Guide, Oregon DOT


Illustration from North Carolina Complete Streets Guidelines, North Carolina DOT Sample bridge cross-section with bicycle lanes and sidewalks
Illustration from North Carolina Complete Streets Guidelines, North Carolina DOT



Bridge and Overpass Access

Barriers to movement such as rivers, freeways, canyons, and railways may present severe impediments to bicyclist travel. Bridges built to accommodate all modes of travel are typically preferable since they connect with the existing street network. If separated bicyclist/pedestrian facilities are provided, security issues must be addressed. Bridges must be properly designed to provide safe, accessible approaches, with sufficient space for bicyclists to navigate ascents and descents as well as across the overpass, and safe riding surfaces that take into consideration expansion grate design and seam placement that minimizes hazards to bicyclists. Bridges should also be well-lit. The traffic volumes and speed, as well as bridge length, will all help determine the appropriate accommodation for bicyclists. In locations where bicyclists are expected to ride in the travel lane, a shared-lane marking may be appropriate. It is important to also consider the future growth to the area as bridges are built to last over 50 years.

If retrofit measures are needed for existing structures, space on the bridge may be provided on the street; on walkways if they are wide enough to safely accommodate pedestrians and bicyclists; or even on a separate deck as was done on the Steel Bridge in Portland (see case study). If sidewalk access is provided, ramps should provide bicyclists direct access from the street. Sidewalk access may be desirable if traffic volumes and speeds are high, the bridge is long, and there is insufficient roadway space (outside lanes or shoulders are narrow) to safely accommodate bicyclists.

When bicyclist space is provided near bridge railings or near motorized traffic, extra horizontal width or a buffer of two feet or more is recommended to protect bicyclists in the event of a crash or wind blast, especially on higher speed bridges or high spans where wind gusts may be strong. Railings should also be provided. The American Association of State Highway and Transportation Officials (AASHTO) recommends a railing height of at least 42 inches.

Access from adjoining streets should be as direct as possible to reduce out-of-the-way detours for bicyclists, and designs should endeavor to minimize conflict points at entrances and exits.


Bridges and overpasses built for all modes of travel provide continuity of access for bicyclists and prevent significant detours for bicyclists due to unsurpassable natural or built barriers.


  • Width of travel lanes and existing walkways; length and height of span; and motor vehicle travel speeds and volume should all be considered when determining the best place to provide space for bicyclists.
  • Extra buffers may be needed for "shy distance" from railings or from traffic to protect bicyclists from sudden wind blasts or gusts.
  • Bicyclist access on multimodal bridges should be provided since these bridges connect with the existing street network. Separate facilities may be desirable to prevent long detours for bicyclists (if additional multimodal bridges are infeasible) or to connect multi-use paths or separate corridors.
  • Ideally, similar bicycle facilities should be provided on both sides of the bridge to reduce wrong-way riding and minimize conflicts at each end of the structure.

Estimated Cost

Varies widely, depending on whether a new bridge is constructed or a retrofit of existing installation is provided. The type of facilities and changes implemented also affect cost.

For retrofit treatments, Portland examples include from $20,000 for restriping to add bike lanes on an existing deck cross section to $10 million for adding a cantilevered shared path to an existing bridge.

Bicycle and pedestrian overpasses are generally very expensive, though some cost savings can be realized depending on the materials used. Cost information is typically provided as a lump sum cost, but can also be presented as a cost per square foot.

Overpasses (not included in table below) have a range from $150 to $250 per square foot or $1,073,000 to $5,366,000 per complete installation, depending on site conditions.

Min. Low
Max. High
Cost Unit
# of Sources (Observations)
Wooden Bridge
Pre-Fab Steel Bridge

The cost for specific types of bridges can vary substantially, based on the specific situation, materials, and other factors, as demonstrated in the table above for wooden and pre-fab steel bridges.


To view references for this countermeasure group click here.

Case Studies

Portland, Oregon
Ithaca, New York
Pulaski County, Arkansas