FAIRFIELD — State transportation officials can now speak the words that motorists commuting on Highway 12 through Jameson Canyon have long been waiting to hear.
“We are nearing the end of the project,” state Department of Transportation Senior Transportation Engineer Elias Moussa said Thursday.
The target date to finish major work is Sept. 5, Moussa said. But, he added, the unexpected could happen and this date is tentative.
What’s clear is that, though the precise day might vary, the end of the road is in sight for the Highway 12 widening project.
The $130 million project began construction in spring 2012 and extends 6 miles from Interstate 80 in Solano County to Highway 29 in Napa County. Caltrans is transforming a road that was two lanes for most of its length into one that is four lanes and is adding a concrete median barrier. Its stated goals are to improve traffic flow and safety.
Work on the 3-mile Napa County segment for the most part wrapped up in April and motorists since have been able to use all four lanes there, two in each direction. But the 3-mile Solano County segment is taking longer and remains only two lanes, one in each direction.
The reason: a hill towered above the old version of the highway in Solano County, with the steep slope hugging the roadway’s side. To make room for the extra two lanes and shoulders, workers had to remove a large portion of the hill. They trucked away 340,000 cubic yards of dirt and rock.
“This basically is the project for Solano County,” Moussa said as he stood near the hill.
Workers have created a massive, three-tier retention wall along a half-mile stretch of the carved-out hill. At the highest point, the wall is broken into tiers that are 20 feet tall, 55 feet tall and 55 feet tall, for a total of 130 feet. The cement walls have been sculpted and stained to resemble rock.
Ultimately, two eastbound lanes will run at the base of the lower retention wall and two westbound lanes will run along a shelf carved out along its top. At one point, the eastbound lanes will be 20 feet below the westbound lanes.
Since mid-January, both eastbound and westbound traffic have used the two lanes on the upper shelf. Workers on the lower roadbed section have been largely out of sight as they’ve done such things as work on the lower retention wall and replace a Vallejo water line.
This past week, workers have been paving. Through Thursday morning, they had put down 7,000 tons of asphalt that came from the Syar Industries Lake Herman Quarry near Benicia, with 3,000 tons to go.
The next milestone for motorists is scheduled Aug. 1. Then the one lane of eastbound traffic is to shift to the right-hand lane of the lower section that workers are paving. Westbound traffic will remain in the right-hand lane of the upper shelf. The left-hand lanes on both levels will be used by workers as they top the first-tier retaining wall with a median barrier.
A final step will be putting down a layer of rubber asphalt on the pavement on both levels and doing the permanent striping.
When final paving was done on the Napa County side several months ago, work took place during the day because temperatures were too low at night for paving. That in turn caused traffic delays. On a few of the worst days, it took an hour to drive the 6 miles from Interstate 80 to Highway 29 in the afternoon.
But Moussa expects only minor delays as the Solano County side wraps up. Higher temperatures during the summer allow for paving to be done at night.
Reach Barry Eberling at 427-6929 or [email protected] Follow him on Twitter at www.twitter.com/beberlingdr.