Mare Island Western Approach

Mare Island Causway BridgeSummary:

The Mare Island Causeway western approach structure is located on “G” Street at the westerly end of the Mare Island Causeway Bridge, originally built in 1934.

The existing western approach is a three-span timber framed structure with two intermediate bents that have been supplemented with temporary shoring to address significant structural deterioration and stress deficiencies.

The proposed replacement bridge is an estimated 52 foot long simple span concrete structure. The purpose of this project is to permanently address the deterioration, stress deficiencies and increase the safety of the traveling public. The project will improve load capacity as well as improve seismic characteristics.

The proposed project includes replacement of approach road asphalt concrete (AC) pavement, sidewalk and installation of new handrails, signing and striping. The work will be broken into two phases.  Please see the Staged Construction Plan for more information.

Traffic pattern during Construction period: One-way traffic onto Mare Island over Causeway & exiting Mare Island thru SR-37.

Budget: $3.5 M Engineer’s Estimate

Status: Under Construction

Traffic Updates

12/31/15 - The new bridge structures on both lanes of the Mare Island Causeway Western approach are complete. The contractor will joint he two sections on Thursday, December 31. The entire causeway will be closed to traffic from 9:00 a.m. to 6:00 p.m. in order to facilitate this work. All vehicles will be detoured across highway 37 to the Walnut Avenue exit. You can view the detour here.

10/7/15 - In order to lift panels into place on the new portion of the causeway, all traffic across the causeway will be suspended from 9 a.m. to 6 p.m. on October 16th. Please view the press release for more information.

9/22/15 - Two (2) of the four (4) Piles/supports have been secured 80 linear feet underground and concrete poured in its place. The remaining two Piles/supports will be installed at 70 linear feet, tested and poured within two weeks. One-way traffic heading west onto Mare Island is still in effect.


  • March 2015 - Bid Opening
  • April 2015 - Project Award
  • July 2015 - Construction Begin
  • February 2016 - Anticipated Construction Completion

Causeway Detour Map

Bridge detour map

 Press Releases and Public Notices

Project Documents

Go to the following location to access project files.  Visit the bids and proposals page for the most current proposal.

If you have questions contact Srinivas Muktevi, Project Manager (707) 651-7107,