Reported yesterday in the Marin Independent Journal
Opening up the Alto Tunnel for bike and pedestrian use could cost as much as $52 million, according to a new report that looks at ways to better connect Corte Madera and Mill Valley.
The county commissioned San Rafael-based Alta/LandPeople to conduct a study of three specific bicycle and pedestrian routes connecting the cities, a key segment of the county's north-south bikeway in Marin.
The $225,000 study, paid for with federal funds, will be discussed at a meeting Wednesday in Mill Valley.
It estimates reopening the half-mile Alto Tunnel between the two communities would cost $48 million to $52 million, which would include adding a 10-foot-wide bike path and an 8-foot-wide pedestrian walkway.
"We definitely question the high price tag on the tunnel and are wondering why it has come in so high," said Kim Baenisch, executive director of the Marin County Bicycle Coalition, who thought a high contingency budget might have driven up the figure.
She noted the Cal Park Hill Tunnel, which is being repaired to connect San Rafael and Larkspur for rail as well as bike and pedestrian access, has a budget of $25 million.
But that tunnel is about half the length of the Alto Tunnel, which was built in 1884 and is in the former Northwestern Pacific Railroad right-of-way.
The tunnel is 16 feet wide, 20 feet tall and approximately 2,200 feet long, and served as a single-track rail tunnel for nearly 90 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 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. The middle 1,600 feet of the tunnel remains sealed off, according to the bike coalition, which supports the reopening of the tunnel.
"It provides a flat, easy route for everyone, even the least skilled cyclists," Baenisch said.
The study also looks at ways to improve the existing connectors, the Horse Hill route and the Camino Alto route, which require steep climbs and force bicycles to mix with car traffic.
"Those hills and traffic can be intimidating," Baenisch said.
For Horse Hill, the study suggests adding a parallel pedestrian path and designating an existing path for bikes along East Blithedale Avenue, and the possibility of a sunken and raised pathway to reduce grades and separate traffic, as well as other improvements. Basic improvements would cost about $5 million, a sunken path about $10 million.
Improvements for Camino Alto might involve widening bike paths and extending existing sidewalks, for about $5 million.
"Marin has some unique topography in this area, so we wanted to look at these three options," said Craig Tackaberry, assistant director for the Marin County Department of Public Works. "Now we are looking for some comment and feedback on the report."
A meeting on bike and pedestrian connections between Corte Madera and Mill Valley is set for 6:30 to 8:30 p.m. Wednesday at Edna Maguire Elementary School, 80 Lomita Drive, Mill Valley.