Mount Lassen Drive Bridge Rehabilitation Project

Rosemarie Gaglione, Director, Public Works
Mount Lassen Drive Bridge

Project Description:

The County of Marin has received federal funding to replace/rehabilitation local bridges that have been identified as structurally deficient and functionally obsolete. Mount Lassen Bridge over Miller Creek is one of the bridges identified for rehabilitation and a project has recently been initiated to conduct environmental studies and to begin design work. Protecting the riparian habitat and maintaining traffic will be high priorities for the project.

Mount Lassen Bridge is located just north of Lucas Valley Road in Lucas Valley. Mount Lassen Drive is a two-lane roadway that provides connectivity for local residents to Lucas Valley which is a principal arterial road that connects to Highway 101 . The existing bridge was built in 1925 and is a three-span, reinforced concrete slab structure. The bridge needs to be rehabilitated for the following reasons:

  • Minor cracks in the bridge deck are allowing water intrusion which over time could degrade the structural concrete and steel.
  • Scour from the creek has caused undermining of the structure.

The project improvements will primarily be focused beneath the bridge where the creek scour is undermining the structure. The bridge deck will also be sealed as part of the project. No improvements are federally funded outside of the immediate bridge. Access to the Mount Lassen Drive will be maintained at all times. The neighborhood will be mailed project fact sheets during the design phase, as well as, follow-up notification in advance of any construction on the site.

The project is 100% federally funded through the Highway Bridge Program. The federal funds are being administered through the Caltrans Local Assistance Program.

The anticipated project timeline is as follows:

Summer 2015
Begin Environmental Studies and Preliminary Engineering
Fall 2019
Conclude Environmental Review
Fall 2019
Initiate Detailed Design
Fall 2020 Final Design Plans
Summer 2021 Begin Construction


Community outreach and engagement are fundamental to any project. Since the nature of this project is primarily a bridge repair project we do not anticipate an extensive dialogue about the design repairs. However, project fact sheets will be distributed to the local community and their will be opportunities to ask questions and provide feedback. In relations to the environmental process, any draft environmental documents or findings will be made public in accordance with the California Environmental Quality Act (CEQA) and National Environmental Protection Act (NEPA) before they are finalized. Also, the neighborhood and local businesses will be fully notified of any construction on site well in advance of the work.

Stay Informed:

For more information, contact Chris Good, Associate Civil Engineer.