The California Department of Transportation (Caltrans) has started construction on new carpool lanes on the San Bernardino Freeway (Interstate 10).

The $195.5m project will reduce traffic congestion for more than 200,000 motorists, who commute on the route between Baldwin Park and West Covina every day.

Caltrans director Malcolm Dougherty said that investing in I-10 benefits all Californians, because it is a critical link between Santa Monica and the Arizona border, which helps power the state’s economic engine.

"Investing in I-10 benefits all Californians, because it is a critical link between Santa Monica and the Arizona border, which helps power the state’s economic engine."

"Locally, I-10 serves commuters, parents taking children to school and businesses that rely on it to get goods and merchandise to their customers," Dougherty said.

The new project will see the addition of one four-mile-long carpool lane in each direction between Puente Avenue in Baldwin Park and Citrus Street in West Covina.

Soundwalls will also be constructed to lower traffic noise in adjacent neighbourhoods.

The I-10 improvements form the second of three projects, which will create 40 miles of continuous carpool lanes between downtown Los Angeles and San Bernardino County.

The third project is slated to begin in 2015.

760,000 people every day travel on Los Angeles County’s 268 miles of carpool lanes, with an additional 188 miles of lanes currently being planned or under construction.