Bonneville Lock and Dam - Navigation Lock 1 Bridge Replacement

The project consists of replacing the existing bridge with a new fixed bridge on a new alignment and to provide for partial demolition of the existing bridge.

The new fixed bridge will be a single-span steel girder bridge with a concrete deck. The bridge width will be 34’4½” out-to-out, with two 11’0” travel lanes, two 2’0” shoulders, a 5’0” sidewalk, and the superstructure will consist of four (4) built-up steel plate girders. The replacement bridge alignment is located immediately downstream of the existing bridge and, at its northern terminus, will fit entirely between the existing bridge and the Bonneville Power Administration transmission tower which is located to the south. Approach roadways will also be constructed to tie into the existing roadway alignment. The new fixed bridge will be located over the existing navigation channel and will provide an under clearance that is larger than is currently present under the existing bridge. The north abutment will be a concrete stub abutment with spread footing anchored into rock. The south abutment will be a concrete abutment that is supported by drilled shafts. To mitigate seismic hazards, portions of the existing bridge will be removed as part of the bridge construction requirement. The existing bridge provides for critical vehicular access to the Bonneville project that must remain open for the entirety of the construction project. This will likely require the contractor to construct the project in phases. In

addition, lead and asbestos removal will be required as part of this requirement. Working within environmental and seasonal restrictions and barge crane lifting will be required in close proximity to a high voltage power line will also be necessary during performance of the required work.