A $4.2-billion project to build a subway between downtown Los Angeles and Westwood took a major step forward Thursday when the Metropolitan Transportation Authority voted to approve a preliminary route plan.

The recommended route would run between the Wilshire/Western Metro station to the Westwood Veterans Administration Hospital, a distance of nine miles. The board expects a one year environmental review period, with constructing starting as soon as 2013.

The plan would extend the current Metro system to Beverly Hills, Century City and Westwood. A one-way trip from downtown to Westwood is forecast to take 25 minutes.

“This day is nothing short of historic,” Los Angeles Mayor Antonio Villaraigosa, who campaigned on the subway project, said in a statement. “Five years ago, everyone thought the subway was just a dream, but today it’s very real and the only question is how fast we can build it.”

Don Knabe, a county supervisor and chairman of the MTA board, called the plan “a major milestone in the history of transit in Los Angeles County.”

The Metro board also approved plans for a $1.32 billion regional connector to link various subway lines together without the congestion of a central hub downtown.

To pay for the construction of both projects, Metro plans to use revenue from Measure R, which raised the county sales tax. Measure R revenue would serve as collateral and repayment for long-term bonds and federal loans.