Opening the Alto Tunnel

Closing the Safety Gap: Marin County Bicycle Coalition releases report
on the Mill Valley to Corte Madera Bicycle and Pedestrian Study

Photo-simulation by Doug Nelson - RHAA

During open time at the Marin County Board of Supervisors’ meeting on January 26, 2010, the Marin County Bicycle Coalition provided a 64 page report recommending changes and pointing out omissions associated with the draft Mill Valley to Corte Madera Bicycle and Pedstrain Corridor Study which was completed by consultants Alta/LandPeople at a cost of $225,000 to the County. Final comments on the Study are due on Friday, January 29 to clando@co.marin.ca.us. 

The three routes analyzed were the Horse Hill route, Alto Tunnel, and Camino Alto. The stated purpose of the Study is “to facilitate planning and public participation and conduct preliminary engineering and design work to identify the relative feasibility of each route.” It is intended to “provide useful information for future discussions and decisions” about building bicycle and pedestrian improvement between Mill Valley and Corte Madera, which represents one of the biggest non-motorized transportation gaps and safety hazards in all of Marin. 

The County of Marin worked for 10 years to secure the funding necessary for this important study, but unfortunately, the draft provided by the consultants raises as many questions as it answers, and does not provide adequate information about the methodologies used to draw conclusions about projected costs and about the proposed use of the facilities. The Study fails to analyze the potential hazards and liabilities associated with a possible Alto Tunnel collapse if nothing is done to stabilize the degrading tunnel built in 1884. The Study also does not adequately address economic, health, public safety, and emergency egress issues and benefits, all of which could be maximized if the Alto Tunnel were opened.

The Marin Countywide Plan, adopted in 2007 includes a focus on sustainability, climate protection and health, and contains a goal for 20% of trips in the County to be made by walking and bicycling by the year 2020. In 2006, Marin’s bicycle and pedestrian mode share was already at 13.6%, and a fall 2009 County study showed that bicycling has more than doubled in Marin over the past decade. As transportation represents 62% of greenhouse gas emissions in Marin, and state law now requires the region to cut emissions, there is increasing attention on reducing our ecological footprint. We can make a dent in reducing carbon emissions by building facilities that will get a maximum number of people out of cars. 

To get its money’s worth and to fulfill the stated purpose of the Study, MCBC respectfully requests that the County of Marin instruct consultants Alta/LandPeople to conduct a major revision of the Study and to address and answer all of the comments and questions raised in the MCBC Report. We should take advantage of the opportunity and get the Study completed properly. 

The MCBC looks forward to continuing to work with the County of Marin to make Marin a model bicycle and pedestrian community for the nation. This will improve public health, reduce traffic, increase safety, decrease greenhouse gas emissions, and benefit communities, residents, and the economy throughout Marin.

Where is the Alto Tunnel and what is its history?

The Alto Tunnel was built in 1884 and is located in Marin County along the former Northwestern Pacific Railroad right-of-way, connecting Mill Valley and Corte Madera. The tunnel is 16-feet wide and 20-feet high, approximately 2200 feet (0.4 miles) long, and served as a single-track rail tunnel for nearly ninety years. In 1958, there was a substantial upgrade to the northern portal, which remains intact and in good condition today. The tunnel remained open until 1971, when substantial bulkheads were added at each portal to prevent entry. In 1975, a plug extending approximately 125-feet was added near the north end of the tunnel and in 1981, there was a collapse at the southern portal. The southern portal area was stabilized in 1982 with gravel and earth fill, which remains today. The middle 1600-feet of the tunnel remains sealed off.

FAQs

Read the MCBC’s letter to the County, 3/31/09

On Tuesday, November 18, 2008, the Marin County Board of Supervisors approved of a $225,000 contract with Land People to conduct the Mill Valley to Corte Madera Bike and Pedestrian Corridor Study, which is part of Marin County’s Nonmotorized Transportation Pilot Program (NTPP). The study will be focused on three corridors between Mill Valley and Corte Madera: Camino Alto/Corte Madera Avenue, Alto Tunnel, and Highway 101 via the “Horse Hill” path.

The contract is providing for corridor planning and geotechnical feasibility work, public outreach, bicycle and pedestrian use projections, and preliminary design work. Current public outreach includes (or will include) a project website, fact sheets, an e-newsletter, press releases, presentations at public meetings, informational meetings with neighborhood groups, and an online survey. The Alto Tunnel analysis will build on lessons learned from the Cal Park Tunnel Multi-Use Path project.

The first public meeting took place on March 4, 2009 as part of this study.  The County solicited public comment regarding existing conditions, concerns and opportunities for each of the 3 routes.  The Marin County Bicycle Coalition submitted comments that focused on, amongst other things, the criteria for evaluating each of the three routes.  

The completed report will indicate the additional costs necessary to move to the next level of accuracy for the Alto Tunnel rehabilitation as a subsequent phase.

For more information about this study (timeline and scoping documents) along with previous scoping documents, including the 2001 Alto Tunnel Scoping Study prepared by Quincy Engineering for the Marin County Department of Public Works, please visit:
http://www.walkbikemarin.org/projects_millvalley.php

The Marin County Bicycle Coalition thanks the Board of Supervisors for moving forward with the Mill Valley – Corte Madera Gap Closure study; this project is an important component of the North-South Greenway, a plan to create a flat and direct bikeway separated from cars, parallel to Highway 101, from Sausalito through Sonoma County.

For more information, email andy@marinbike.org

• How many people are projected to use the Alto Tunnel on a daily basis?
• Why would the County of Marin want to restore Alto Tunnel?
• What have been the experiences when other bicycle and pedestrian tunnels have been opened throughout the United States?
• What is the condition of the Alto Tunnel today?
• How much would it cost to re-open the Alto Tunnel and make it a part of the North-South Greenway?
• Where would the money come from to open the Alto Tunnel?
• Would funds to open Alto Tunnel take away from schools, parks, emergency services, or other projects?
• How would security and maintenance be handled?
• How will opening Alto Tunnel affect the neighbors?
• Are there any environmental considerations?
• How can I help?

Download this FAQ sheet in PDF form

How many people are projected to use the Alto Tunnel on a daily basis?

The March 2008 Marin County Bicycle and Pedestrian Master Plan indicates that the tunnel would essentially provide a level, separated connection from Sausalito to Corte Madera, Larkspur the upper Ross Valley, and central San Rafael. Preliminary 2001 estimates indicate that the tunnel could attract an additional 800 bicyclists during a typical weekday, many of whom were driving previously. This is approximately 33 bicyclists per hour, based on a 24 hour time line, or 50 bicyclists per hour if the concentration of use takes place between 7 AM and 10 PM.

Why would the County of Marin want to restore Alto Tunnel?

The County of Marin owns the property on either side of the tunnel, and the railroad right-of-way has always been slated for use as a transportation corridor. Since the 1970s, the County has had plans for a North-South Greenway which would run along the Northwestern Pacific Railroad right-of-way, spanning Marin County from North to South, providing access to transit centers, businesses, schools, and town centers. There is currently a well-used multi-use pathway that extends for three miles, from Sausalito and through Mill Valley, leading right up to the south portal of Alto Tunnel. Another pathway continues north from the north portal of Alto Tunnel, through Corte Madera and Larkspur, approaching the Larkspur trestle. Here are some benefits of "closing the gap" in the North-South Greenway through opening the Alto Tunnel for bicycle and pedestrian use:

• Improved Safety: Currently, bicyclists and pedestrians have two choices for traveling between Mill Valley and Corte Madera, neither of which are appealing. They can go out of their way to the "Horse Hill" (Alto Hill)/Highway 101 Freeway path (which includes 200 total feet of climbing and carbon monoxide fumes from the freeway traffic), or travel over Camino Alto, which is a 320 foot climb along a busy, narrow, winding road. Police statistics from Corte Madera indicate that there have been numerous injuries of non-motorized users along Camino Alto over the past ten years.
• Decreased Traffic Congestion: Opening Alto Tunnel would create a straight, flat pathway that would be accessible to people of all ages and physical abilities. People would be able to commute to San Francisco, access the Manzanita Transit station, shop at businesses on either side of the hill, attend soccer practice and other after-school activities, go to the Mill Valley Community Center and the pool, and to commute to the College of Marin. Many auto trips could easily be replaced with bicycle or pedestrian trips once the tunnel is open.
• A Route for People in Wheelchairs: Opening the Alto Tunnel would provide a socially-equitable transportation option for people in wheelchairs; there are two residential communities that support disabled people in the vicinity of the Alto Tunnel in Mill Valley.
• Physical Health Benefits: The U.S. Centers for Disease Control and Prevention estimate that 300,000 Americans die each year due to complications associated with obesity and sedentary lifestyles, and that 67% of US adults are overweight or obese. The CDC recommends 30 minutes of physical exercise, five times a week, for adults and states that replacing trips by automobile with walking or cycling is one of the best ways the get this exercise.
• Environmental Health Benefits: The useful route provided by the tunnel will replace motor-vehicle trips, reducing air and water pollution.
• Emergency egress benefits of Alto Tunnel: There has been much attention placed on the slogan “Get Ready Marin” which urges residents to be prepared in the event of a disaster. The tunnel would provide an important emergency egress should there be a fire or other emergency.

What have been the experiences when other bicycle and pedestrian tunnels have been opened throughout the United States?

Several years ago, the County of Marin commissioned the Rails-to-Trails Conservancy to do a study of tunnels, which have been opened throughout the United States for use by bicyclists and pedestrians. The report concludes that tunnels are overwhelmingly safe, that they are valued by communities, and that there is a trend throughout the United States to open more tunnels to non-motorized use. "Tunnels on Trails, A Study of 78 Tunnels on 36 Trails in the United States" covers issues related to: safety, liability, costs of tunnel restoration, construction, maintenance, and the impacts of tunnels on the existing transportation network and surrounding communities. The study also found that property values often increased, and that while all neighborhoods had concerns before the tunnels were opened, some of the most vocal opponents of the tunnels came to be the most frequent users and supporters of the tunnels once they were opened. Click here to read the RTC study on-line in PDF format.

What is the condition of the Alto Tunnel today?

The northern 170-feet was inspected in June, 2001 and determined to be in good structural condition. The exact condition of the middle 1600-feet of the tunnel is unknown at this time; however, further investigations are being proposed to better determine the condition in this zone. The existing redwood timbers may be in various stages of decay, depending on the amount of moisture in the sealed portion of the tunnel. Regardless of the existing conditions, the existing redwood timber support system will have to be replaced and augmented with a new concrete liner for both structural safety, aesthetics, and to eliminate any fire danger. The Southern 350-feet was backfilled with gravel in 1982 and will have to be excavated and supported with a new concrete structure.

How much would it cost to re-open the Alto Tunnel and make it a part of the North-South Greenway?

No one knows exactly how much it would cost to re-open the Alto Tunnel, which is one reason that the County of Marin’s Mill Valley – Corte Madera Gap Closure study was undertaken in 2009. The study is analyzing Alto Tunnel, the Horse Hill route and Camino Alto, and should provide more information about estimated costs, projected use, and more. A draft of the study should be released in the fall of 2009.

Where would the money come from to open the Alto Tunnel?

There are a variety of potential transportation funding sources for the project. In addition, once a commitment is made to making a capital project a reality, new funding sources often emerge. The 1100 foot long Cal Park Hill Tunnel is being funded by the Bicycle Transportation Account, Transportation Funds for Clean Air Program, Transportation Enhancements, and Regional Measure 2, through a collaborative effort by the County of Marin and Sonoma Marin Area Rail Transit (SMART). When assessing the costs for Alto Tunnel, it is important to also look at the costs for other transportation projects. The HOV gap closure project which added one traffic lane along Highway 101 for 4 1/2 miles from Terra Linda to Larkspur cost more than $150 million. It will cost $800 million to widen the Highway one lane in each direction from Novato to Petaluma.

Would funds to open Alto Tunnel take away from schools, parks, emergency services, or other projects?

No. The funds that would be used to open the Alto Tunnel would be transportation project funds; they would not take away from schools, parks, emergency services, etc.

How would security and maintenance be handled?

Once the Alto Tunnel is opened, there will be annual costs to maintain and operate this facility. Some security measures that have been used in other tunnels and are planned for Cal Park Hill Tunnel include: security cameras, police patrols, and lighting. These are likely the types of features that we would see if Alto Tunnel were reopened. Because the portals to Alto Tunnel enter and exit in Mill Valley and Corte Madera, cooperation and coordination among the towns and the County of Marin would be essential.

How will opening Alto Tunnel affect the neighbors?

There are some neighbors near Alto Tunnel who want to see the tunnel re-opened, and some who are against the project and have major concerns. It will be important to open up more of a dialog with the communities immediately near the portal. There are many ways to minimize any possible negative impacts that an open the tunnel may have. Landscaping can create a visual barrier to the pathway, and sound mitigation can help to reduce any errant noise. Signs can be posted urging tunnel users to please be quiet and respect the neighbors. In addition, as with any transportation or development project, neighbors’ concerns must be weighed against the benefits of the project to the community at large.

Are there any environmental considerations?

All transportation projects have environmental considerations; the Alto Tunnel project would need to go through review under CEQA, the California Environmental Quality Act. If the County of Marin were to determine that they were ready to move forward with opening the Alto Tunnel, the appropriate departments within the County of Marin would determine the type of environmental review necessary. Because this project is a "replacement or reconstruction of existing structures or facilities" it has a different status of review than an entirely new transportation project.

Overall, opening the Alto Tunnel would produce significant health and environmental benefits for Marin County. People's health would benefit from increased walking/jogging/cycling, and environmental benefits would be accrued from motor vehicle trip reduction. The existence of a flat, straight, car-free route would attract people who might walk or bicycle today, but are dissuaded due to the hills and current levels of automobile traffic on surface streets.

How can I help?
For more information on how you can help get the Alto Tunnel opened, please contact Andy Peri at andy@marinbike.org or visit the Marin County Bicycle Coalition website.

Last updated July 2009