Maxwell Bridge Replacement Project

Maxwell Bridge Replacement Project

Caltrans and the City of Napa will replace the existing Maxwell Bridge , an existing vertical lift bridge, with a new four lane, fixed skyway bridge, twin span, immediately upstream of the existing bridge. Each span will be approximately 528 meters long and 13.57 meters wide and will support two lanes of traffic, and emergency shoulder, and pedestrian and bicycle traffic. Prior to the work on the new or existing bridge an existing low-pressure sewer foce main, which runs under the Napa River, will need to be relocated to accommodate the new bridge piers. The new force main will be relocated approximately 30-40 meters north of its existing location. The new 24" force main will be installed under the Napa River using either a microtunneling technique or horizontal directional drilling. The existing bridge will remain in operation until traffic is shifted onto the first of the twin bridges at which time it will be demolished by dismantling its steel segments with saws or cutting torches. The freed segments will be removed by a crane or lowered onto barges in the River and taken to salvage or disposal facilities. At this point the eastern embankment will be removed and the floodplain will be excavated. The second span will then be constructed, and the existing river piers and footings from the old bridge will be removed. The pilings that the old footings rest on will be cut off below the channel bottom. Work within the river on the new bridge will consist of the construction of new columns to support the bridge structure. The column foundations are anticipated to be constructed using sheet pile coffer dams.

Napa

Napa