By Daniel Kelley
PHILADELPHIA (Reuters) - Transit workers in the greater Philadelphia area began a strike over proposed new contracts early on Saturday, after failing in efforts to reach a deal with the regional transit authority before a midnight deadline, officials said.
Unions representing about 400 engineers and electricians who operate trains that connect the city and its suburbs called for a walkout at 12:01 a.m., when a mandatory 30-day cooling off period expired.
The strike will not affect the city's subways or buses, though it could put thousands of cars on the road as residents of small towns dotting the region are left with little choice but to drive to work.
About 126,000 people use the 13 regional rail lines, which stretch from the city's northern suburbs to Wilmington, Delaware.
Pension benefits were the main sticking point in the negotiations, Jerri Williams, a spokeswoman for the Southeastern Pennsylvania Transportation Authority (SEPTA), told reporters.
Both sides had returned to the bargaining table at 8 p.m. on Friday under orders from federal mediators.
SEPTA has issued contingency plans that call for more buses on the road and higher capacity on subways. But they also urged commuters to seek flexibility at work, because lines are already running at capacity during rush hours.
The workers have gone without a contract since 2009, but the issue came to a head this week after SEPTA management said it would impose a new contract.
The unions have balked at the plan because it was not negotiated and does not include retroactive pay increases for the years since the last contract expired.
The region is already suffering major jams on Interstate-95 after I-495, which bypasses Wilmington, was closed because support columns on a bridge had tilted.
Officials have urged commuters to take the regional rail line to Wilmington to alleviate traffic congestion.
Under federal law, the strike could be delayed if President Barack Obama appoints a presidential emergency board to mediate the dispute, which could delay the strike for up to 240 days during negotiations.
"We feel all it does is to continue the possibility of a strike at another date," SEPTA's Williams said of the presidential emergency board.
(Editing by Clarence Fernandez and Elaine Hardcastle)