There are many instances where trails will pass beneath vehicular bridges to create a grade separated path. Vertical clearance is critical, and for longer underpasses lighting may be needed.
- Maintain 8’-0” minimum vertical clearance or higher as required by municipal/partner needs.
- 2% max trail cross slope.
- The typical 3’-0” minimum level shoulder should be maintained on either side of trail.
- Incorporate guardrail or other safety barrier between trail and lower slope, where lower slope is in excess of 3:1, stabilized with hard material or along a wall with a fall of greater than 2’-6”.
- Drainage from overpass above should be routed away from trail. Water should never fall directly on trail.
- Should be designed to withstand potential flooding. Fencing should be cable rail system where likely to flood.
- Design should consider flood debris removal and sediment removal, allowing maintenance equipment access as required by maintenance partner. Design should also consider maintenance requirements for overpass.
Underpass walls provide a valuable opportunity for the installation of visual elements that elevate brand awareness, enhance user experience and communicate interpretive messages. Great Rivers Greenway has created an environmental graphics toolkit that contains various designs and elements that can be considered during the planning and design process.
STANDARD CROSS SECTION
COMPONENTS: Click below for more information on each component.