Pedestrian bridge design standards in Illinois, Iowa and Wisconsin
Pedestrian bridges can be constructed in several ways — over divided highways, expressways, freeways and waterways, under roadways, through roadway embankments, and over and under railroad tracks. These bridges generally fall under the following four categories.- Truss. These can be used at almost any site and should be built with a camber (upward bow) to limit the risks of a downward bow under loading. Truss bridges are a cost-efficient design with the ability to span short and moderate lengths (up to 250 feet for pedestrian use). Typical applications include bridges over roadways or large bodies of water. Simple truss bridges can also be manufactured and assembled off-site, simplifying the construction process.
- Girder (Beam). Most bridges are built with girders or beams, with the load being taken by the girders underneath the deck carrying the pedestrian traffic. For recreational or trail bridges over roadways, a girder bridge with a concrete deck and proper fencing is often used. Engineers also tend to combine multiple bridge structure types, such as concrete slab approach spans with steel girder center spans.
- Arch. These bridges are visually aesthetic but are not always a feasible option because of budget and space constraints. Arch bridges are best suited for locations where the bridge is substantially higher than the river or roadway – picture a deep gorge or canyon. With the relatively flat midwest topography, arch bridges are not typically seen in Illinois, Iowa and Wisconsin.
- Long span. Large and long pedestrian bridges include cable-stayed bridges and suspension bridges. The most famous example is the Golden Gate Bridge in San Francisco. While these bridges are aesthetically pleasing, they are expensive to construct and maintain. By incorporating innovative engineering and inspiring design, these pedestrian bridges are functional works of art. Some unique cable-stayed footbridges and suspension bridges across Illinois, Iowa and Wisconsin are listed on the National Register of Historic Places.
The following table highlights some general pedestrian bridge design requirements as defined by the standards in Illinois, Iowa and Wisconsin.
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General pedestrian bridge design requirements in Illinois, Iowa and Wisconsin |
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Features |
General features include bridge span (straight line dimension), width, bridge system type, member components and camber. |
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Engineering |
Engineering requirements include loading, specifically the design approach, wind load, seismic load, serviceability criteria and snow load. |
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Geometry and clearances |
Consider the geometry and clearances for pedestrian bridge cover profile and grade, and ramps and other physical requirements following the ADA Standards for Accessible Design guidelines. Depending on the anticipated usage of a pedestrian bridge, vertical and horizontal clearances should also be considered. |
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Materials |
Concrete, steel, aluminum, wood and Fiber Reinforced Plastic or Polymer (FRP) are common materials for pedestrian bridges. All mounting devices and bolted connections should be made of corrosion-resistant materials. |
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Fabrication |
Components can be manufactured off-site or assembled at the jobsite. All cutting, drilling and welding fabrication should be done by experienced tradespeople using the proper tools and equipment per industry standards. |
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Railings |
For bridges for pedestrian and bicycle use, railings should be installed at a minimum of 42 inches above the bridge deck. For equestrian use, railings should be installed at a minimum of 54 inches above the floor deck. For grades greater than 5%, handrails should be provided for all stairs and ramps. |
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Decking |
Depending on the intended use of the bridge, decking materials should be wood (pressure-treated timber/composite decking), precast concrete or high-strength fiberglass. All pedestrian bridge decks should have non-skid surfaces. |
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Lighting |
The length of the pedestrian bridge, its location and concerns about pedestrian safety should determine the lighting requirements. Lighting should be energy efficient and consideration should be given to the impacts to the natural environment. |
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Submittals |
All submittal drawings, diagrams and calculations should be signed and sealed by a licensed professional or structural engineer to be submitted to the client. |
Please note that this is not a comprehensive list. You should consider state-specific code requirements and bridge standards while developing a pedestrian bridge design. The pedestrian bridge design standards also require you to procure information about the site and soil conditions, conduct soil tests and geotechnical analysis, develop an abutment plan and secure permits before building a bridge. Partnering with a team of licensed transportation and structural engineers can provide you with the needed information and guidance on your bridge design project – from conception to completion.
Partner with Fehr Graham for pedestrian bridge development
At Fehr Graham, our experienced transportation and structural engineers are committed to ensuring pedestrian safety across the Midwest and beyond. From conducting traffic studies and developing pedestrian bridge designs to construction management and securing funding, we help communities build robust infrastructure that complies with local regulatory standards. We have been featured in the Roads and Bridges magazine because of our extensive work on transportation projects across Illinois, Iowa and Wisconsin. To learn more about how Fehr Graham can help your community design bridges that comply with pedestrian bridge design standards, contact us or call 815.562.9087.
| As the firm’s Lead Transportation Engineer, Fehr Graham Principal Noah Carmichael, PE, leads notable, complex and high-profile transportation infrastructure engineering projects. He works closely with municipal and governmental partners on public infrastructure planning and identifies funding opportunities to support community capital investment goals. Reach him at This email address is being protected from spambots. You need JavaScript enabled to view it.. |