PHILADELPHIA (AP) - The city's largest transit union said Friday that no progress has been made in contract negotiations, tamping down hopes of an end to a strike that has idled subways, buses and trolleys for four days.

Gov. Ed Rendell, who has been brokering negotiations, said early Friday that Transport Workers Union Local 234 was reviewing a new contract proposal from the Southeastern Pennsylvania Transportation Authority and that he was hopeful there would be an agreement by nighttime. A transit agency spokesman also said union leaders were examining a proposed agreement.

But union spokesman Jamie Horwitz said that, while both sides met until 2 a.m., no progress was made. Horwitz declined to say if the union was reviewing a new proposal and said that the union didn't plan any public announcements Friday.

The union represents about 5,000 bus drivers, subway and trolley operators and mechanics. They walked out early Tuesday in a dispute largely centered on pension benefits.

As the strike drags on, city officials plan to closely monitor attendance at schools, as well as the number of visits to emergency rooms and community health centers, said Douglas Oliver, a spokesman for Mayor Michael Nutter.

The city declared a health emergency over swine flu last week. If hospital visits and school attendance are down significantly, Oliver said, Nutter could decide to seek a court injunction to halt the strike on the basis of a public health danger; students are getting swine flu vaccines at school.

The union had threatened to strike while the World Series was in town last weekend, but negotiators continued bargaining after Rendell threatened "significant consequences" if that happened. The union went on strike hours after the series between the Phillies and Yankees shifted back to New York.

SEPTA's regional railroad is still running because those workers are represented by a different union, but that system has experienced problems of its own this week.

On Wednesday, a railcar caught fire as it headed downtown, causing delays and confusion but no serious injuries. On Thursday, a packed commuter train struck and killed a rail worker during the morning rush, stranding hundreds of riders as lines had to be shut down for hours.

Neither accident was related to increased volume due to the strike, SEPTA said.