The South Street bridge shut this morning for a long-awaited reconstruction project expected to take two years and cost $67 million.
The span over the Schuylkill has linked Center City with University City for 85 years and has borne nearly 23,000 vehicles a day. It was closed to traffic at 10:39 a.m., about one hour behind schedule.
Highway engineers have deemed the crumbling bridge "structurally insufficient."
Crews will now begin to prepare it for demolition.
Shortly before 9:30 a.m. a group comprised of about 20 elected officials and community members from the Center City Residents' Association and the South Street Bridge Coalition, formally closed the bridge by walking across it.
At 10 a.m., the eastbound ramp from I-76 to the bridge was closed, then the westbound ramp.
Just after 9 a.m. a group of 50 first and second graders from the Philadelphia School at 25th and Lombard Streets braved the frigid temperatures to walk back and forth on the bridge.
"We might be studying local bridges in the future and it's good for them to see this, one teacher said as the group spent about 10 minutes taking photographs of the trek.
Cathy Von Elm, who works at the library at the University of Pennsylvania, walked across the bridge's pedestrian path this morning. "It's inconveniencing but it's better to have the bridge fixed," she said.
Von Elm said she will now use the Walnut Street Bridge to get to work.
Jogger Catherine Schmitt, 50, of Philadelphia detoured from her regular route to cross the bridge this morning.
"I heard it was closing so I thought I'd take a final run," she said.
Until a more pedestrian-friendly span is unveiled in 2010, traffic will be diverted to the Walnut Street Bridge several blocks north.
Patients and staff headed via I-76 to the sprawling hospital complex are advised to use the University Avenue exit.
Russell Meddin of Bike Share Philadelphia was one of the last people to officially ride over the bridge.
"It was fun, windy and chilly, a very good end for something good to come," Meddin said.
The new bridge will have new bike lanes and a wider pedestrian walkway.
"It will be a more people-friendly bridge," said Alex Doty, of the Bicycle Coalition of Philadelphia.