The Metropolitan Transportation Commission and Caltrans are now both recommending that the state make Highway 12 through Jamieson Canyon Road a four-lane road funded by new congestion relief bonds.

MTC staff had recommended a less costly three-lane option, but on Wednesday morning commissioners representing the nine Bay Area counties said four lanes made for a better project.

“This is really great news,” said Napa County Supervisor Bill Dodd, who intends to lobby to get final sign-off from the California Transportation Commission on Feb. 28.

Jamieson Canyon Road is a major commute bottleneck between Napa and Solano counties. Proposals for local transportation sales taxes in Solano and Napa counties that would have widened this stretch of highway were defeated by voters in June.

The MTC considers Jamieson Canyon widening its No. 2-rated Bay Area project for funding from Proposition 1B, Gov. Arnold Schwarzenegger’s transportation bond approved in the November election, Dodd said.

Both the MTC and Caltrans support a trimmed-down four-lane connection from Interstate 80 to Highway 29. By leaving some curves on the Solano side and installing a median barrier on only half of the six-mile length, the cost can be cut from $190 million to $133 million, said Jim Leddy, executive director of the Napa County Transportation Planning Agency.

State bonds would cover $84 million, with Napa and Solano counties expected to come up with the remaining $49 million from other highway funds, Dodd said.

The Napa County Transportation Planning Agency and MTC staff had proposed a $107 million three-lane option, with two westbound lanes and just one eastbound.

By keeping the cost down, they hoped that the project might win the favor of the California Transportation Commission, which won’t have enough money to fund all the recommended projects statewide.

Caltrans convinced the MTC that a three-lane Jamieson Canyon wasn’t an adequate solution, Dodd said. “They want to do it right,” he said.

It should strengthen Jamieson Canyon’s chances for bond funding if Caltrans and the MTC have a unified request, Dodd said.

Prior to the MTC meeting at the end of February, Dodd said he would enlist community leaders to write letters to the CTC supporting the project.

Besides being a big bottleneck during morning and evening rush hours, Jamieson Canyon slows the movement of goods, which harms the wine industry, he said.

Leddy, who worked for two state senators before taking his NCTPA job in December, has political connections in Sacramento to strengthen Napa’s case, Dodd said.

The proposed four-lane design would save money by not realigning as much roadway on the curvy stretch in Solano County, Leddy said. More funds would be saved by installing a median barrier along half the highway. The barrier would be placed in the areas with the highest accident rates, Leddy said.

If the scaled back design is funded by the CTC, Napa gets improved traffic flows as well as greater safety, he said.

Solano County and Caltrans have a multi-phase plan to improve the I-80/I-680 connection and route Highway 12 through traffic off the interstate.

Projects that receive state bond money must be under construction by 2012. Local sponsors are hoping for a 2010 start.