After about three month's work, the planned 140-foot tunnel is 20 percent complete, contractors say. It is being fashioned from more than 200 tons of steel and concrete in a process they describe as "quite a task."
To build the $3.4 million tunnel, workers are digging down from the top, then pouring concrete into reinforced molds that shape a 15-foot-wide passage.
In a few days, workers will pour asphalt over the first tunnel section and move the operation into the middle of the street. But before that can be done, massive steel plates must be jiggled from the perimeter of the project area by a backhoe attached to a huge, vibrating clamp. The plates keep the street and surrounding earth from caving in on the project. Gravel and asphalt will then be poured in and traffic will be redirected over the new tunnel section.
Coordinating the effort has been a challenge, said project manager Rodrigo Macaraeg, partly because high pressure gas lines had to be relocated, as well as water mains and fiber-optic lines. The work on the tunnel is being done by a crew of five workers, while another four people work on the trail itself.
Meanwhile, a more pedestrian-friendly southbound Highway 85 onramp may be completed by next week, giving cars a side lane to slow down in before making a right turn off of El Camino Real.
By next spring, the city hopes to have the tunnel complete, though winter rains may upset the schedule, said Chris Halvorsen, construction engineer. The trail has already been extended from the former trail head at Yuba Drive to El Camino Real — though it has yet to be paved.
The current trail stops at the tunnel, where at least 15 acres of open space along Highway 85 will remain gated off until 2009, when the next phase is complete, said Bob Kagiyama, the city's principal engineer. The open space winds between the freeway and the creek, and has historically been a campsite for the homeless, as evidenced by tents and bags of belongings scattered around the area. City workers said the homeless are moving farther upstream as trail construction progresses.
The post-tunnel phase begins in the summer of 2008 and will take the trail to a prefabricated bridge over the creek to Sleeper Avenue, encouraging access from the Waverly Park neighborhood.
From there, Stevens Creek winds its way under Highway 85, where it runs near open spaces that can seen on the east side of 85. To connect the trail, an unfunded bridge over the highway will cost $7.1 million to construct — but has already been designed. The trail will cross back over Highway 85 at the site of the former water tower behind Mountain View High School.
The grand vision for a Stevens Creek Trail going from the Bay to the Santa Cruz Mountains is nearly complete in Mountain View, but the final bridge to Mountain View High is a long-term goal at this point, Kagiyama said. An environmental impact report and feasibility study for the final trail section was approved in 2004.
"We've made some substantial progress to date," Kagiyama said. "It is pretty amazing."
Farther upstream, Cupertino, Sunnyvale and Los Altos have preliminary plans to continue the trail, though private property extends into much of the creek, meaning that public streets will have to connect the trail through certain areas. Just upstream from there in Stevens Creek Park, the trail continues climbing into the Santa Cruz Mountains.