The Mare Island Causeway Bridge is more than a way to cross the water. It is one of the most important physical links between mainland Vallejo and Mare Island, carrying residents, employees, visitors, cyclists, and pedestrians between two parts of the city with very different histories and identities.
In 2026, that connection is undergoing a major preventive maintenance project designed to extend the bridge’s serviceable life and improve safety. The work is also creating a temporary traffic pattern that anyone traveling to or from Mare Island should understand before heading out.
According to the City of Vallejo, the current bridge project is expected to continue through March 31, 2027. During the present construction phase, one bridge lane is being maintained for westbound traffic toward Mare Island, while eastbound vehicles leaving the island must use Highway 37 to return to the mainland.
That makes the project especially relevant not only to Mare Island residents but also to workers, businesses, visitors, and anyone exploring one of Vallejo’s fastest-changing areas.
What Is Happening to the Mare Island Causeway Bridge?
The Mare Island Causeway Bridge was originally built in 1934 and has served as a critical connection between Vallejo and Mare Island for decades. Vallejo previously completed an upgrade in 2016 that replaced a section of timber bridge structure with steel, but additional maintenance is now required.
The current work is a preventive maintenance project rather than a completely new bridge. Its purpose is to address aging components, improve pedestrian and driver safety, protect structural elements, and extend the useful life of the existing crossing.
The City lists a construction cost of approximately $19.8 million for the project. More important for everyday travelers, the work involves several different bridge systems rather than one simple resurfacing job.
Why the Historic Bridge Needs Major Maintenance
A bridge operating in a marine environment faces constant exposure to moisture, salt, weather, vehicle traffic, and normal structural aging. Mare Island’s causeway also has a historic lift-span structure and serves pedestrians as well as vehicles, so maintenance has to address multiple components at the same time.
Preserving the bridge matters because Mare Island continues to function as a residential, employment, cultural, industrial, and recreational destination. As discussed in our guide to Mare Island redevelopment in 2026, long-range plans envision significantly more activity on the island over time.
Repairs Go Far Beyond Repaving the Road
The City’s project description includes bridge deck and pile repairs, sidewalk replacement, ADA improvements, lighting work, handrail repairs, concrete crack and spall repairs, and maintenance of marine-safety components.
The steel lift span, towers, and historic bridge logo are also scheduled for repainting. Crews are applying protective treatments to the bridge deck and replacing underwater anodes, which help protect submerged metal components from corrosion. The bridge’s fender system is also being repaired to improve protection around marine traffic.
Taken together, those improvements explain why the work requires an extended construction schedule. Much of the project is about protecting components visitors may never notice when simply driving across the bridge.
The Current Traffic Pattern Is the Biggest Change for Drivers
For most people, the most noticeable impact is traffic circulation. Under the City’s current construction plan, the one available lane across the causeway is being used for westbound traffic at all times.
That means drivers traveling from mainland Vallejo toward Mare Island can continue using the bridge. However, vehicles traveling eastbound from Mare Island back toward mainland Vallejo need to leave via the Highway 37 connection.
This is not the normal two-way bridge pattern, so visitors who are unfamiliar with Mare Island should plan their return route before arriving. A trip that looks simple on a map can require a different path when leaving the island.
The City says Public Works staff are monitoring traffic and may make adjustments when needed. Motorists should follow posted construction signs and allow additional travel time, particularly when they have an appointment, work shift, ferry connection, or other time-sensitive destination.
How to Plan a Visit to Mare Island During Construction
The bridge work should not automatically keep visitors away from Mare Island. The island remains one of Vallejo’s most interesting places to explore, with historic architecture, waterfront views, former naval facilities, open spaces, businesses, and a distinctive industrial landscape.
The key is understanding that your route onto the island may be different from your route back.
Plan Your Westbound Arrival and Eastbound Return Separately
If you are traveling from central Vallejo to Mare Island, the causeway remains an important westbound connection. When it is time to leave, however, expect to use Highway 37 rather than simply retracing your route across the bridge.
Checking navigation immediately before departure is a good idea because construction conditions, traffic backups, incidents, or short-term adjustments can affect travel time. Visitors should also pay attention to official City of Vallejo notices rather than relying only on an older map or social media post.
Once transportation is planned, Mare Island can easily become part of a larger Vallejo day. Explore our Mare Island page for local ideas, then browse restaurants in Vallejo or Vallejo coffee shops for stops before or after your visit.
The bridge project is also worth considering when planning events or appointments on the island. Build extra time into the return trip, particularly if you need to reach downtown Vallejo, the ferry terminal, or another destination immediately afterward.
Why the Bridge Project Matters Beyond Temporary Traffic
It is easy to view road construction only through the inconvenience it creates. In this case, however, the Mare Island Causeway project is closely connected to a much larger question: how Vallejo maintains infrastructure while Mare Island and the nearby waterfront prepare for future growth.
The bridge already serves existing homes, businesses, schools, industrial activity, events, and visitors. At the same time, Mare Island is undergoing a major Specific Plan update that could eventually bring substantially more housing, employment, and activity to the island.
Infrastructure Will Help Shape Mare Island’s Next Chapter
The condition and capacity of transportation infrastructure will influence how successfully future development functions. New neighborhoods and employment centers do not operate independently from bridges, roads, utilities, sidewalks, drainage systems, transit, and emergency access.
That is why the current causeway maintenance project should be viewed alongside other major Vallejo planning discussions rather than as an isolated repair job.
Bridge Work and Redevelopment Are Part of a Bigger Vallejo Story
Mare Island is not the only part of this area receiving renewed planning attention. Mainland Vallejo is also developing a new waterfront planning framework. Our article on Vallejo waterfront revitalization in 2026 looks at efforts to improve the relationship between downtown, the waterfront, transportation, economic activity, public spaces, and Mare Island Strait.
Together, these projects show why reliable connections across and around the strait matter. Someone living or working on Mare Island depends on infrastructure linking the island with the rest of Vallejo. Visitors benefit when destinations are easy to reach. Businesses benefit from predictable access. Emergency services need reliable routes regardless of construction or future growth.
Pedestrian improvements are another important piece of the maintenance project. The bridge carries people on foot as well as vehicles, and the planned sidewalk replacement and ADA upgrades can help create a safer and more accessible connection.
For people exploring Vallejo recreationally, those improvements complement the city’s broader network of outdoor spaces. You can find more ideas through our Vallejo parks and outdoors directory or browse things to do in Vallejo.
short-term
The short-term reality is that bridge construction requires some extra planning. Eastbound drivers leaving Mare Island cannot currently use the bridge in the usual way, and that may add time to everyday trips. Work zones can also change how familiar streets feel.
The longer-term goal, however, is a safer and more reliable historic crossing. The City expects construction to continue through March 31, 2027, with repairs intended to extend the bridge’s serviceable life and improve conditions for drivers and pedestrians.
Anyone traveling to Mare Island during this period should check current City updates, follow posted detours, and avoid assuming that the route used to enter the island will also be available for the return trip.
The inconvenience is temporary, but the infrastructure being repaired plays a lasting role in Vallejo. As Mare Island evolves and the waterfront receives new investment, maintaining this nearly century-old connection is one piece of preparing the city for what comes next.
