Negotiations between Philadelphia's transit agency and the union representing 5,700 workers are ongoing amid a threat of a strike at midnight if an agreement on a new contract isn't reached.
The Southeastern Pennsylvania Transportation Authority and the union met throughout the weekend and were scheduled to continue contract talks Monday.
A strike would affect Philadelphia bus, trolley and subway lines but not regional rail lines and service in areas outside the city. The city system's daily weekday ridership is about 800,000 trips, or about 400,000 people. More than 60,000 public, private and charter school students use the system to get to and from school.
Union officials say pension and health care benefits are key issues, but differences also remain on non-economic issues such as schedules, break time and driver fatigue.