NORTH BAY — The Metropolitan Transportation Commission plans to lend the state up to $200 million to sustain five threatened Bay Area highway projects under construction, including widening of Interstate 80 south of Fairfield and expansion of Highway 101 north of Santa Rosa, three projects with bids to be awarded in coming months including added lanes on Highway 101 north of Rohnert Park, plus traffic monitoring projects.

The commission voted Wednesday to authorize its Bay Area Toll Authority to purchase as much as $200 million in state general obligation bonds to make up for Proposition 1B transportation money the state suspended in mid-December to make up for billions in budget deficit and weak market demand for state bonds.

That funding freeze affected $1 billion going toward 90 Bay Area road projects.

“There still are details to work out,” said MTC spokesman John Goodwin.

Namely, the toll authority and the state will need to negotiate an interest rate for the private placement.

Other terms of the agreement are that bond proceeds would go to Bay Area projects, the Pooled Money Investment Board would continue to reimburse the projects up to the purchase amount and the bond term would not exceed three years.

Caltrans needed $155 million to sustain or start construction on the eight projects covered by the proposed bond purchase, according to the commission.

Projects under construction that would continue are:

High-occupancy vehicle lanes and interchange improvements along 7.5 miles of Highway 101 between Steele Lane in Santa Rosa to the central Windsor exit. State shortfall: $53 million

HOV lanes along Interstate 80 from the Cordelia interchange with Highway 12 and Interstate 680 north through Fairfield. Shortfall: $16.6 million

Two segments of southbound HOV lanes on the Sunol Grade along Interstate 680 in Alameda County. Shortfall: $3.7 million

An eastbound HOV lane on Interstate 580 also in Alameda County. Shortfall: $19.9 million

Traffic monitoring in several counties. Shortfall: $5.8 million

Projects in the process of being awarded are:

HOV lanes on 1.3 miles of Highway 101 from Wilfred Avenue in Rohnert Park north to existing HOV lanes. Shortfall: $41 million

Two more phases of southbound HOV lanes on the Sunol Grade. Shortfall: $15 million

Had work stopped on the projects, the state said it would have faced tens of millions of dollars in shutdown and restart costs.

For example, the lowest bid for the Wilfred project came in at $41 million, about 30 percent, or $19 million, below engineer estimates, according to Suzanne Smith, executive director of the Sonoma County Transportation Authority.

“Had the MTC not provided backup to the state, we would have not only lost the savings to the bids but also had to suspend the job on the north section,” she said. “That would have cost something that was not insignificant.”

She hopes the details of the bond purchase will be completed in time to award the Wilfred contract in mid-February.

However, more than $600 million in other Bay Area projects ready for bid awards in the next six months have an unknown future. That includes widening about six miles of Highway 101 from Rohnert Park to north Petaluma, improvements to the Interstate 580-Highway 101 interchange in San Rafael and more HOV lanes on Interstate 80 in Solano County.