President Obama has forced striking SEPTA workers to return to the job.
The president granted Gov. Tom Corbett's request to create a presidential emergency board to mediate the dispute between the SEPTA and its engineers and electricians unions.
Mr. Obama called for "a swift and smooth resolution'' of the dispute. More than 400 workers went on strike at midnight on Saturday.
All workers returned o the job at 12:01 a.m. Sunday, according to SEPTA officials. The president's order doesn't force the two sides to resume direct talks with each other. But they must participate with the board's process, which typically involves written submissions and hearings.
After 30 days, the board must recommend to the president how the dispute should be resolved.