County of Marin - News Releases - Alto Tunnel Ownership Study

For Immediate Release
November 10, 2015

Update Provided on Alto Tunnel Ownership Study

Work continues on proposal to turn 131-year-old tunnel into bike/pedestrian corridor

San Rafael, CA – New information is being presented about the Alto Tunnel, a long-closed railroad passageway that could become a key pedestrian and bicycle link between Corte Madera and Mill Valley.

The boarded-up north entrance to the Alto TunnelStaff with the Marin County Department of Public Works (DPW) released new details on their project webpage and will be presenting the findings of the research at a meeting set for 5:30 p.m. November 17 at the Mill Valley Community Center. The purpose of the meeting is to provide an update to the community part way through the Alto Tunnel Study on the results of the right-of-way research.  Next up is a geotechnical evaluation of the Alto tunnel to refine the cost estimates for possible reconstruction of the tunnel for use as bicycle and pedestrian pathway.

The 2,220-foot tunnel, built in 1884, served as a railroad tunnel for almost 90 years before it was closed in 1971. It experienced several interior collapses and subsequent engineered stabilizations. A movement to reopen the tunnel for non-motorized transportation has gained steam over the past few decades, and in 2006 the Alto Tunnel connection was identified as one of the top-priority non-motorized transportation projects in the county based on public input. All but three short segments of the tunnel are held by the County; two easements are owned by the Northwestern Pacific railroad and one by a private party.

Today, bicyclists use either Camino Alto/Corte Madera Avenue or the Highway 101 “Horse Hill” bike path through neighborhood streets to get between Corte Madera and Mill Valley. The steep topography, lack of facilities and speed of vehicles have made these routes a challenge. Just this year, Mill Valley added a new uphill bike lane on Camino Alto by widening the shoulders and repaving the road to provide more width on the uphill side. Although the new lane improved the safety for bicyclists, the topography is still too much for many people to use it as a suitable route between Mill Valley and Corte Madera. The option of having a relatively flat route between the two communities by way of the Alto Tunnel is more attractive to people who aren’t comfortable bicycling or walking with cars on steep, winding roads.

The November 17 meeting is designed to be an informal way for the project staff to inform stakeholders about the latest facts on the project. Later, a geotechnical feasibility phase to further refine the cost estimates and the proposal would be brought back to the community for more in depth input.

“We’re not at a decision point on the Alto Tunnel right now,” said DPW Principal Civil Engineer Bob Goralka. “We’d like to report out what we’ve found in our research about the right-of-ways part way through the study. People interested in the topic of right-of-ways are welcome to attend the informal meeting. In the meantime, everyone can review all the information that will be at the November 17 meeting on the project webpage.”

Two studies – the Mill Valley to Corte Madera Bicycle and Pedestrian Corridor Study and the Alto Tunnel Study – were funded by Marin’s $25 million federal Nonmotorized Transportation Pilot Program (NTPP), part of the U.S. Department of Transportation. The NTPP projects serve people of all ages and abilities, and provided safe, convenient places to walk or ride. In addition to reduced greenhouse gas emissions, Marin benefitted with traffic congestion relief, low-cost travel alternatives and improved public health.

Since the NTPP program was launched in 2006, many Marin projects have benefited from the federal support, including the Cal Park Hill Tunnel, Enfrente-Commuter Connection in Novato, Los Ranchitos/Las Gallinas Bike Lanes in San Rafael, and several stairway and sidewalk projects.

The Mill Valley Community Center is at 180 Camino Alto. If you can’t attend the meeting but remain interested, email Senior Project Planner Carey Lando at before December 1.


Carey Lando
Senior Project Planner
Public Works

Marin County Civic Center
3501 Civic Center Drive
Suite 304
San Rafael, CA 94903
(415) 473-5078
CRS Dial 711

Email: Carey Lando