Introduction
Trail bridges that are constructed in a poor location or that are the wrong size are more susceptible to failure. Bridges typically are the most expensive item on a trail, so it's important to get them right the first time. Good bridge siting involves many disciplines. It requires careful attention to preliminary engineering, hydraulics and hydrology, trail alignment, and environmental and geomorphic concerns. All of these concerns must be addressed to make sure that the structure is appropriate for the site.
This report focuses on locating new single-span trail bridges shorter than 50 feet (figure 1), but the same considerations can be used for relocating or reconstructing trail bridges. The National Environmental Protection Act (NEPA) requirements, landownership issues, Federal and State permitting requirements, and trail bridge types are beyond the scope of this report and will not be discussed. You can find more information on trail bridge types, decks, rail systems, materials, and abutments on the Trail Bridge Catalog Web Site http://www.fs.fed.us/eng/bridges/.
Highlights...
- Siting trail bridges properly will increase the likelihood that the stream will continue functioning properly and that the bridge will be useful throughout its planned life.
- Knowledge of the Rosgen stream classification system can help resource managers choose suitable sites for trail bridges.
- Trail bridges that are sited properly are less likely to be damaged or destroyed during a major flood.
Figure 1—A new fiber-reinforced polymer trail bridge in the Sam Houston National Forest.
