NRCS Maine State Office - Low Volume Road Application Bridge Design

The Maine Natural Resources Conservation Service (NRCS) requires the services of an Architect-Engineer (A-E) firm to develop bridge design criteria according to the current American Association of State Highway and Transportation Officials (AASHTO) Load Resistance Factor Design (LRFD) Bridge Design Specifications for low volume road applications in Maine.

The Maine NRCS are replacing failing, undersized culverts with “stream smart” structures that will allow for aquatic organism passage while still allowing landowners access to farm and forest land.  Typical bridge designs completed by the Maine NRCS are for local and privately owned roads with low traffic volumes and low speeds.  Occasionally bridges are designed for pedestrian and/or livestock crossing only.

All bridge design loads shall be designed in accordance with the current AASHTO LRFD design specifications with a minimum design vehicle load of HL-93.  Bridges will be used by farm equipment, logging equipment and road vehicles; logging equipment on privately owned roads will typically be considered overloaded vehicles.  

Typical bridges are built for a single landowner in remote areas.  Therefore, these bridges can be considered low speeds and low volume use. Bridges are built by local small contractors with light equipment to include excavators up to 30 ton.  Consider building bridges from locally available materials including sawn lumber.  The proposed bridge design procedure will accommodate bridge designs for various sizes, loads and materials to custom fit any application in Maine.