The goal of the Highway 12 Jameson Canyon Road project was to widen two sections of Highway 12, a heavily traveled road connecting the Highway 80 corridor to Napa and the northern counties of California.
The road was open throughout all phases of construction, which made the project all the more challenging. Bringing in materials and hauling them off, as well as mobilizing operations, was difficult due to the road being open. To work around this issue, all major haul-off operations took place at night, when traffic was heavily reduced.
Because this section of Highway 12 passes through a canyon/ravine area, three large soil nail retaining walls had to be built. Each wall was over 2,000 ft long and altogether totaled 120 ft in height. With the highway open throughout construction, a rock/debris catch fence capable of stopping car-sized boulders had to be designed and installed before the wall installation could get under way.
“What was unique about the project is that not only did it involve extensive excavations and extremely tall soil nail retaining walls, but they also needed to be aesthetically pleasing, including sculpted concrete and staining to mimic the surrounding landscape,” Jared Herrington, project manager for Ghilotti Construction Co., told Roads & Bridges.
Coordination of many moving parts was an important part of making this project a success. The Solano and Napa county sections of the project were managed by two different project teams and had to be in sync as much as possible. In addition, as a part of this project, almost 5,000 ft of 36-in. welded steel pipe waterline was replaced for the city of Vallejo, adding an extra level of coordination.
Landowner and homeowner communication also was an important component of this project, because residents up and down Highway 12 dealt with many access modifications to their driveways, etc., and all parties wanted to keep impacts to a minimum.
The project is located within multiple environmentally sensitive areas, which meant that it had to remain within strict constraints. No major environmental impacts resulted from the project. R&B
Project: Highway 12 Jameson Canyon Road
Location: Napa/Solano County, Calif.
Owner: California Department of Transportation
Designer: California Department of Transportation
Contractor: Ghilotti Construction Co.
Cost: $35.6 million
Start Date: May 2012
Completion Date: August 2014