Shaker Boulevard over the Knox River Engineering Study

In 2011, Tropical Storm Irene washed out the existing bridge that carried Shaker Boulevard over the Knox River. The existing substructures were removed, and the bridge was replaced by a temporary steel truss bridge with concrete foundations. The channel slopes at the bridge were regraded to form an approximate 15-foot-wide channel with rip-rap-covered slopes. The temporary bridge is approximately 72 feet long and spans beyond the top of the new channel slopes.

The travel lane of the temporary bridge is just 14 feet wide, which only allows one car at a time to pass over the bridge. The approach roadway leading to the bridge is approximately 19 feet wide. The roadway profile was raised a few feet to accommodate the temporary bridge.

BETA is currently developing an engineering study that explores options for completely replacing the existing truss with a new permanent bridge. An approximate 60-foot span bridge will widen the channel at the existing bridge in order to restore the natural bank’s full width of the river. A hydrologic and hydraulic analysis is being performed to determine a proposed bridge opening size that will meet NHDOT standards.

Soils at the site are soft and may require pile foundations. A jointless integral abutment bridge on piles is being evaluated as part of the study. The superstructure will consist of steel or precast concrete stringers.