OAKLAND — BART and its major employee unions on Monday announced a labor deal that would give workers a 10.5 percent pay hike over four years, avoid the threat of another crippling strike and pave the way for the transit agency to float a $3.5 billion bond measure in November to modernize the aging system.

BART management on Monday called the tentative agreement a win that moves aside labor negotiations so they can focus on repairing a system that was disrupted by painful worker strikes in 2013 and mechanical failures in recent months.

“Both sides acknowledged that we need to focus on rebuilding this system,” General Manager Grace Crunican said. “Both sides agree that we need to focus on service to our riders. We need to keep the Bay Area moving, and we know it.”

The deal with unions representing some 3,000 employees includes pay raises of 2.5 percent over two years beginning in 2017, followed by two years of 2.75 percent hikes. It extends a 2013 contract in which employees received a 16.4 percent raise over four years.

That earlier contract also increased pension and health care contributions from employees, which will remain the same under the new agreement. In addition, BART employees continue to receive a $1,000 bonus if ridership exceeds expectations.

The timing of the agreement ahead of the current contract’s expiration next year and the November election drew its skeptics, who speculated the deal could be a bow to pressure from local and state politicians and boost the chances of the bond measure passing.

In February, state Sen. Steve Glazer, D-Orinda, and other local leaders penned a letter urging BART to come up with an agreement before the measure is placed before voters.

BART Director Zakhary Mallett voted against the 2013 contract in an 8-1 vote and said he will do the same this time.

“Extending a bad contract is a bad thing to do,” Mallett said Monday. “What this board has a history of doing is kicking the can down the road by caving to striking workers. I would not pass it by my colleagues to be swayed by those ultimatums” from political leaders.

Assemblywoman Catharine Baker, R-Dublin, said she is glad BART negotiated a contract extension early but disappointed the deal preserves overly generous pay and benefits for workers.

“I see this as a very small baby step heeding our call to get a labor deal done early to avoid strikes. They should be applauded for that,” Baker said. “But there is a lot more work to be done. This agreement extends a contract that was too generous.”

Joe Tuman, a professor of political and legal communications studies at San Francisco State University, said BART management made a politically smart move before the election.

“It’s very clear that the 2013 strike woke up a lot of voters,” said Tuman. “Most people, whether they held labor or management responsible the last time around, were equal parts angry at everybody. It was very unlikely, I think, that you could convince voters about the viability of this bond measure in large numbers if you also had the threat of another strike looming on the horizon.”

Joel Keller, a BART board member from Brentwood, said he can’t decide whether the deal is a good one until all the details of the pact are aired publicly and analyzed. BART officials did not release how much the agreement will cost taxpayers.

“There are some good things, like buying five years of labor peace,” Keller said. “But I need to understand what the full costs of the agreement are to say whether we’re giving up too much for labor peace.”

Both Keller and Mallett questioned why the negotiations were held behind closed doors.

“I want to hear from the public and our riders, who have been cut out of the process so far,” Keller said.

Members of the ATU Local 15555, SEIU 1021, SEIU Local 1021 Professional Chapter and AFSCME Local 3993 need to ratify the contract before it is officially approved by the BART Board of Directors. The contract does not include BART’s police union.

Staff writer Denis Cuff contributed to this story. Contact David DeBolt at 510-208-6453. Follow him at Twitter.com/daviddebolt.