State Route 1 Lagunitas Creek Bridge Project

The State Route 1 Lagunitas Creek Bridge Project, managed by Caltrans District 4, involves the replacement of the existing bridge over Lagunitas Creek from post mile 28.4 to 28.6 in Marin County, California. The scope of work includes the construction of a seismically stable three-span concrete bridge that is longer and wider than the previous structure, along with roadway widening and the lengthening of a triple-box culvert to improve safety for pedestrians and non-motorized users. Technical requirements include the injection of approximately 360 cubic yards of cementitious grout into 1,392 square feet of liquefiable soils to stabilize the creek bank, as well as the adjustment or replacement of roadside ditches and the installation of a gutter system for scupper water. The project is subject to strict environmental compliance, including the California Endangered Species Act under Incidental Take Permit 2081-2024-054-03 and the California Environmental Quality Act. Official notices of determination from the California Department of Fish and Wildlife and the California Transportation Commission confirm that the project will not have a significant environmental effect, provided that adopted mitigation measures and monitoring plans are followed. Construction will utilize a temporary trestle for non-impact pile driving and temporary noise barriers to protect nearby residences and businesses. Key project administration is led by Ronald Sangalang and Chris Pincetich of the California Department of Transportation.