Foresthill Bridge seismic retrofit update

Work on a Placer County icon: the Foresthill Bridge, continues as the seismic retrofit and painting progresses. The $75 million project began in February. The bridge spans the North Fork of the American River. At this point, the bridge work is about 40 percent complete.

While the retrofit operations are underway, the bridge is closed to permit weight loads. It is important for these above-legal-load drivers to know that this restriction is in force at all times and is not limited to times in which the contractor is actively performing the work. When removing structural steel and replacing it with stronger steel, it is not always possible to get the new piece bolted into place during the same shift.  Legal weight traffic is perfectly safe.

The first work done for the project was the installation of two work platforms under the bridge, in addition to installing a catwalk. These platforms have allowed the Golden State Bridge, the contractor, to begin the retrofit and painting.

Additional structural steel is being installed on the bridge using new and stronger bolts. The abutments at either end of the 2,428-foot span are being strengthened to perform better should a seismic even take place in the area. The contractor has created openings beneath the bridge deck in the concrete boxes at both ends of the bridge that house the abutments. These openings are necessary to get equipment to the abutments to perform the work. Additionally, the contractor has widened the bridge deck, filling in the previously open center median with reinforced concrete. Currently, both traffic lanes have been routed into the north deck; the south deck is reserved for staging equipment.

There are two wind monitors on the bridge. Certain work cannot be performed when winds exceed 50 MPH and other work cannot be performed when winds reach 60 MPH.

Analysis of how the bridge will be affected by the placement of the combined loads (contractors’ equipment, platforms, traffic) has been has been carefully checked and rechecked by registered engineers. Equipment placement on the bridge has been carefully determined and prescribed by analysis. Parking has been affected by construction. However, trailheads remain accessible where it is safe to do so.

“Share the Road” signs are being used during construction to remind motorists to use caution around bicyclists. While the project will not result in new bike lanes, there will be 8-foot shoulders on the bridge, in addition to a separated 5′ sidewalk when the project is complete.

The project is expected to be completed in late 2013 or early 2014.