Route 101 Marin Sonoma Narrows A1

Route 101 Marin Sonoma Narrows A1

To accommodate the Marin Sonoma Narrows High Occupancy Vehicle Widening Project, the bridge at Novato Creek will be widened into its median by ~19 ft. The bridge extension will be a cast-in-place reinforced concrete T-beam superstructure, including new concrete bent caps and abutments. The substructure will consist of Class 140 driven pre-cast concrete piles at the abutments and driven cast-in-steel-shell (CISS) piles at the bents. It is anticipated that four 2 ft diameter CISS piles would be required per bent for a total of 16 piles for the 4 bents. The construction of the CISS piles will include pile driving down the steel pipe pile into the ground, removing the soil inside the steel pile, inserting rebar cages into the pipes and filling the pipes with concrete. To accommodate this work some existing piles will be removed by crane or through use of vibratory methods. To avoid impacts to salmonids, pile installation work will be limited to the June 15 through October 15 dry season. Temporary falsework bents will be placed in the creek with steel beams spanning across the falsework bents. Plywood decking will be placed between the steel beams to allow for the placement of bar reinforcing steel and construction of the superstructure. At the route 101/37 interchange there will be a culvert replaced and a headwall installed with rock slope protection (RSP). As a result ~240 sf of willow thicket and blackberry will be impacted. Approximately 26 cy of native material will be removed and replaced with concrete and RSP for the headwall installation.

Novato, Petaluma

Marin, Sonoma