I-95 bridge collapse repair efforts are underway. See renderings of the temporary rebuild
PHILADELPHIA (CBS) -- Crews continue to work around the clock repairing the portion of I-95 in Philadelphia that collapsed on Sunday.
UPDATE: Collapsed portion of I-95 will reopen within 2 weeks, Shapiro says
Crews were out all night Thursday into Friday morning preparing to build temporary lanes to get traffic flowing through the area again. Plans are underway to reopen a portion of the highway once the crews build three temporary north and southbound lanes.
The debris from the northbound and southbound lanes is cleared, making way for this work. But it's still unclear just how long this fix will take to get I-95 back open to drivers.
The materials needed to do the job are now in place. A police-escorted caravan of trucks carrying recycled materials arrived Thursday at the collapse site from Aero Aggregates in Eddystone, Delaware County.
That company is producing thousands of rock-like chunks made out of recycled glass that will be used to temporarily fill the roughly 100-foot-long gap where the Cottman Avenue overpass used to stand.
Workers will fill that area up to highway level before paving over it. How long is this expected to take? CBS News Philadelphia asked a professor of civil engineering, who says the most time-consuming work will be framing out the retaining walls.
"Once you have that, it becomes like a box, and then you just fill it in layers," Rutgers Professor of Civil Engineering Doctor Husam Najm said.
"I would say to be probably less than four weeks," he said.
PennDOT Secretary Mike Carroll wouldn't give a clearer timeline in a news conference this week.
"We're building it as fast as we can, we're working 24/7, we've made tremendous progress this far," he said.
Here's what construction will look like: Those three temporary lanes north and southbound are highlighted by the red arrows. They're the inside lanes.
Once those lanes are in place and open to traffic, crews will then start to build a permanent bridge from the outside in. We've highlighted those lanes in orange.