The L.A. County Metro board of directors approved a $679.4 million total budget for the Interstate 5 North County Enhancement Project in the Santa Clarita Valley on Thursday, setting the stage for the project to move forward with construction of new carpool lanes.

The I-5 North County Enhancement Project is designed to improve the operations and safety of the freeway corridor, improve the movement of freight and passenger vehicles, and accommodate expected growth between Santa Clarita and Castaic, in large part through the addition of one HOV lane in each direction, along with other improvements along the 14-mile corridor, according to a statement released by L.A. County Supervisor Kathryn Barger’s office.

“This project has been many years in coming and was deemed to be the highest priority for the north Los Angeles County during the bottom-up Measure M process,” Barger, whose 5th District includes the SCV, said in the statement. “I am happy to see these critical mobility improvements moving forward and want to thank our local Santa Clarita Valley stakeholders who have advocated for these enhancements. The I-5 is the backbone for trade in the western U.S. and our federal and state partners recognized the importance of this project by providing significant funding.”

Improvements will also include a 2-mile extension of truck lanes, improvements to auxiliary lanes at multiple locations, and widening or upgrading seven bridges, including the replacement of the Weldon Canyon Bridge in the Newhall Pass.

Measure M, a half-cent sales tax approved by county voters in 2018, accounts for a little more than half of the funding for the I-5 corridor improvements. Local, state and federal revenues contribute to the total budget, which includes an unallocated $101 million for potential risks related to the construction.

Metro — the L.A. County Metropolitan Transportation Authority — has received three bids for the project. Skanska Construction and Santa Clarita’s C.A. Rassmussen Inc. together submitted the highest proposal at $513.6 million. Flatiron Security Paving submitted a bid of $406 million, while OHL placed the apparent lowest bid of just under $390 million.

Brian Hass, a Metro communications manager, said the contract is expected to be awarded to the lowest responsive bidder, and such contracts are typically awarded about 30-45 days after the board’s approval of the project budget. Thursday’s vote authorizes Metro CEO Phillip A. Washington “to negotiate and execute project-related agreements, including contract modifications, up to the authorized life-of-project budget.”

Victor Lindenheim, executive director of the Golden State Gateway Coalition, which has worked to help facilitate the freeway improvement project since the early 2000s, told The Signal earlier this week that the adoption of the budget represents the culmination of years of outreach and advocacy.

“It’s taken 17-18 years to get to where we are,” Lindenheim said. “A lot is being done to prepare for this construction project.”