Strike against San Francisco region's mass transit over

Updated 2:20 a.m. ET

OAKLAND, Calif. The San Francisco Bay Area's main commuter train system and its unions reached a tentative agreement on a new contract Monday night, ending a crippling four-day strike.

The deal, which still requires the approval of union members, was announced by oOfficials representing BART unions, Lt. Gov. Gavin Newsom and BART President Grace Crunican, reports CBS San Francisco station KPIX-TV.

BART spokeswoman Alicia Trost said limited service was to begin Tuesday at 4 a.m. local time on all lines. Trains will likely be running at full strength in time for the afternoon commute.

BART is the nation's fifth-largest rail system, with an average weekday ridership of 400,000.

Workers walked off the job Friday after talks broke down. Commuters endured jammed roadways and long lines for buses and ferries, as they looked for alternate ways around the region.

The contentious talks between BART and its two largest unions dragged on for six months -- a period that saw two chaotic days-long strikes, contentious negotiations and frazzled commuters wondering if they would wake up to find the trains running or not.

"The public expects us to resolve our differences and to keep the Bay Area moving," Crunican said Monday night.

Crunican said there would be no announcements on the details of the accord, but she added, "This deal is more than we wanted to pay."

The key issues were salaries and worker contributions to their health and pension plans.

Talks began in April, three months before the June 30 contract expirations, but both sides were far apart. The unions initially asked for 23.2 percent in raises over three years. BART countered, offering a four-year contract with 1 percent raises contingent on the agency meeting economic goals.

The unions contended that members made $100 million in concessions when they agreed to a deal in 2009 as BART faced a $310 million deficit. And they said they wanted their members to get their share of a $125 million operating surplus produced through increased ridership.

But the transit agency countered that it needed to control costs to help pay for new rail cars and other improvements.

BART workers also walked off the job in early July, shutting down train service for nearly five days.

On Saturday, a BART commuter train returning from routine maintenance struck and killed two workers who were inspecting the tracks.

The National Transportation Safety Board is investigating.

BART officials said in a statement that the manager who was operating the train was an "experienced operator," and the four-car train was being run in automatic mode under computer control at the time of the incident.

NTSB investigators say the BART employee who was operating a train during the accident was a trainee.

James Southworth, the NTSB's lead investigator, said at a briefing Monday that the train was carrying six BART employees who were on maintenance and training duties during a strike by thousands of BART workers. The train was going 60 to 70 mph during Saturday's accident.

Southworth would not say whether the operator was a manager learning to operate the train to provide service during the strike. He did say the trainee had held other positions with BART.