🚨 MAJOR TRAFFIC IMPACT — THIS AFFECTS ALL OF SOUTHERN MARIN
Caltrans is proposing to reduce Highway 1 in Tam Junction to one lane and detour traffic through Tam Valley neighborhood streets for over four months starting in summer 2027

Caltrans plans to reroute Highway 1 traffic onto local roads between Tennessee Valley Road and Flamingo Road, using one-way detours that alternate directions as construction advances.

⚠️ The proposed detour passes through a designated High Fire Severity Zone during peak fire season—raising serious emergency access and evacuation concerns.

This will not just impact Tam Valley—it will impact all of Mill Valley and Southern Marin commuters.

• Daily backups in Tam Junction will worsen and extend further into Mill Valley
• The Blithedale exit will see increased congestion as drivers divert off Highway 1
• Commutes could increase by 20–30+ minutes during peak hours
• This detour will directly impact the safe access of 335 students at Tam Valley Elementary School, many of whom walk and bike.
• Neighborhood streets will become cut-through routes for regional traffic across Mill Valley to avoid Tam Junction 
• West Marin–bound drivers are likely to continue up Marin Avenue and cut through the Tree Streets rather than follow the intended detour
• The project does not add bike lanes to the Coyote Creek Bridge. 
• This is not a local inconvenience—it is a regional traffic disruption and safety issue.

🎯 WHAT WE ARE ASKING FOR
We are asking Caltrans to hold a new, well-noticed community meeting before advancing the current detour plan to evaluate safer alternatives—specifically the feasibility of night work and maintaining two lanes of traffic during the day.

✅ This responsible alternative keeps vehicles on infrastructure designed to carry them, protects school children and families using local streets, avoids impacts to critical flood control infrastructure, preserves emergency access, and maintains this essential evacuation corridor.

A community meeting was held by Caltrans on June 13, 2023, where this detour was first presented. However, no members of the local Tam Valley and Mill Valley community were in attendance... suggesting the outreach failed to reach the people most affected.

Link to community meeting: State Route 1 Bridge Rail Replacement Project Public Meeting

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The project includes removing and replacing the existing bridge rails at Coyote Creek Bridge on State Route 1 (Shoreline Highway), along with widening the bridge by 2 feet on each side—work that does not justify the scale of the proposed impact on the community.

The work does not include replacement of the closed Coyote Creek Pedestrian bridge 

The proposed detour onto Tennessee Valley Road, Marin Avenue and Flamingo Road is unsafe and unnecessary.

Stay updated about this Caltrans project by visiting tamjunction.org and learn more

This petition will be delivered to Caltrans District 4, Marin County Board of Supervisors, and our state representatives. 

Link to Caltrans Project Documents: State Route 1 Bridge Rail Replacement Project EA

🚸 SAFE ROUTES TO SCHOOL — THIS IS THE TOP PRIORITY

Flamingo Road and Marin Avenue are narrow residential streets that serve as Safe Routes to School for Tam Valley Elementary.

🚸 No centerline
🚸 Bike sharrows
🚸 Daily use by children walking and biking

Tennessee Valley Road is also constrained, with limited shoulders and a 35-foot vehicle length limit.

Routing highway traffic onto these streets for several months would create dangerous daily conditions for children and families. It would increase conflicts between vehicles, bikes, and pedestrians and introduce high-speed, high-volume traffic into a neighborhood environment.

This is fundamentally unsafe.

  
🚗 THE SCALE OF IMPACT IS EXTREME

🚗 SR-1 carries ~34,000 vehicles per day
🚗 Flamingo Road is designed for ~1,700 vehicles

That’s an 18× increase on neighborhood streets.

🌊 FLOOD CONTROL AND LEVEE RISK

Flamingo Road sits on and alongside a critical flood control levee system (Zone 3) that protects homes and infrastructure in Tam Valley - Bird Land neighborhood 

🌊 Built on soft bay mud
🌊 Already experiencing settlement in the roadway, homes and levee 
🌊 Actively being stabilized today by Flood Control District 

Routing heavy traffic for months would:

🌊 Accelerate damage to the Cardinal Road levee, which is already planned for reinforcement with a new flood protection wall.
🌊 Increase flood risk during king tides and storms
🌊 Threaten homes, infrastructure, and public safety

This is not just a traffic issue—it is a flood protection issue for the entire community.

 
🔥 WILDFIRE EVACUATION AND EMERGENCY ACCESS

State Route 1 is a critical wildfire evacuation corridor.

🔥 Diverting traffic off SR-1 would impact and slow down evacuation routes
🔥 Emergency response times would be impacted
🔥 Congestion would increase in unsafe locations

At a time of increasing wildfire risk, we must protect—not weaken—this corridor.

 
⚖️ ENVIRONMENTAL REVIEW FAILED (CEQA ISSUE)

The detour was not included in the environmental review.

📅 Negative Declaration: April 14, 2023
📅 Detour introduced: June 13, 2023

This means:

⚖️ No safety analysis
⚖️ No flood risk analysis
⚖️ No public review

This is a clear gap in CEQA compliance.

 
🚫 LEGAL AND INFRASTRUCTURE LIMITS

🚫 7-ton weight limit on Flamingo Road
🚫 Most SR-1 commercial vehicles exceed this
🚫 Roads and bridge not designed for this load

 
✅ A SAFER ALTERNATIVE EXISTS

Night work with lane closures on SR-1:

✅ Keeps traffic on appropriate infrastructure
✅ Maintains evacuation and emergency access
✅ Protects neighborhood streets
✅ Avoids damage to levees and roads

 
🤝 OUR COMMUNITY IS UNITED

Residents, families, and the Tam Valley Elementary community support the project—but oppose this unsafe detour.

 
📢 TAKE ACTION

We urge Caltrans and Marin County to:

🚸 Protect Safe Routes to School
🌊 Protect flood control infrastructure
🔥 Protect wildfire evacuation routes
⚖️ Conduct proper environmental review
🚫 Reject the Flamingo Road detour

 
✍️ SIGN THIS PETITION

Tam Valley is not a detour route.
It is a community—and it must be protected.

 

 

 

 

 

 

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