FAIRFIELD — A $130 million push to widen Highway 12 to four lanes for the 6 miles through Jameson Canyon will see some milestones in coming days and weeks.
What appears to be one project is really two separate projects with separate contractors, one in Napa County and one in Solano County. State Department of Transportation Senior Resident Engineer Elias Moussa said the Napa County side is 90 percent finished and the Solano County side is 70 percent finished.
Workers on the Solano County side over the past year have carved away a large chunk of a hill that stood in the way of the widening. They’ve put two new lanes on a terrace along what’s left of this hill, some 20 feet above the existing two lanes at the highest point and extending for about a half-mile.
Caltrans has scheduled those two new lanes on the terrace to open to traffic at 5 a.m. Thursday. Someday, they will carry westbound traffic only. But when they open, one lane will carry eastbound traffic and one lane will carry westbound traffic.
That will allow Caltrans to close the existing two lanes, which will someday carry eastbound traffic only. Workers can then carve away the final section of hillside, add the final retaining wall, locate a Vallejo water line under the existing road and put in new pavement.
Caltrans wants to get the word out to drivers to expect the lane shift Thursday morning.
“It’s a mini-milestone within the big milestone,” Moussa said.
Another smaller milestone could happen in mid-February in the Napa County segment of the project. That’s when Highway 12 could have all four lanes open from Highway 29 to near the Napa-Solano County line, a distance of almost 3 miles.
This stretch has been paved, Moussa said. Remaining work includes striping the lanes and installing signs.
The biggest milestone, of course, is when the entire Jameson Canyon project is finished. Moussa said that could be as soon as August, weather permitting.
Moussa on Tuesday gave a tour to the media of Highway 12. He showed an animal tunnel where a creek crosses under the highway using a culvert. The animal tunnel is 12 feet tall and 12 feet wide.
Footprints of deer could be seen in the dirt at the tunnel’s entrance.
“See? There’s an underground highway,” Moussa said.
He showed a “waterfall” feature that runs between terraces on the carved-out hill. These are rocks put together in such a way as to resemble a cascade. Water will tumble down the feature only when storms hit and there is enough water draining from the hill.
Highway 12 through Jameson Canyon is a major link between Interstate 80 in Solano County and Highway 29 in Napa County, carrying an average of 32,000 vehicles daily. It has done this with only two narrow lanes for most of its length.
Caltrans, the Solano Transportation Authority and the Napa Transportation and Planning Agency have worked to change this. On April 4, 2012, they had a groundbreaking ceremony to kick off the four-lane widening project.
Since then, Highway 12 through Jameson Canyon has been a construction zone. Motorists have had to put up with slower speeds at times and the periodic overnight closures.
But the end is in sight, perhaps by this summer. Much of the heavy lifting for the project is completed.
Reach Barry Eberling at 427-6929 or firstname.lastname@example.org. Follow him on Twitter at www.twitter.com/beberlingdr.