One of the most congested highways in San Diego, Interstate 805 south of Interstate 8, will be expanded by one lane in each direction thanks to a $100 million grant from the California Transportation Commission.

The new lanes will be reserved for car poolers and mass transit, according to the San Diego Association of Governments, the regional planning agency, which made the announcement June 28.

The grant funds awarded to the San Diego project made up 60 percent of the total money recently given to Southern California. The local project was competing against 12 other transportation improvement proposals in this region, Sandag said.

The commission awarded the funds from Proposition 1B money that state voters approved in 2006, and that authorized $4.5 billion in general obligation bonds to improve congested travel corridors.

The 805 project is slated to begin next year with the contract award for the first phase, between state Route 54 and state Route 94, expected in March.

The contract for the second phase, between Palomar Street and state Route 54, is expected to be awarded in April 2012.

Sandag said it is providing local matching funds on the project, which will go toward building sound mitigation walls and access ramps.

— Mike Allen