Pennsylvania will truck in 2,000 tons of lightweight glass nuggets to help quickly rebuild a collapsed section of Interstate 95 in Philadelphia and crews will work 24 hours a day until they can reopen the critical commercial artery, officials said Wednesday.

Instead of rebuilding the overpass right away, crews will use the recycled glass to fill in the collapsed area to avoid supply-chain delays for other materials, Gov. Josh Shapiro said.

But Shapiro repeatedly declined to estimate how long it will take to get traffic flowing again on the busy East Coast highway.

“We’re going to get this job done as quickly as possible,” Shapiro said at a news conference near the site, over the sounds of heavy machinery working to clear wreckage. He said the work would be done with union labor.

Investigators continued to look into why a truck hauling gasoline went out of control on an off-ramp and flipped on its side, igniting a fire early Sunday that caused the collapse of the northbound lanes of Interstate 95 and severely damaged the southbound lanes.

Workers will fill the gap — which is roughly 100 feet (30 meters) long and 150 feet wide — by piling recycled foam glass aggregate into the underpass area, bringing it up to surface level and then paving it over so that three lanes of traffic can reopen each way, Shapiro said.

“This approach will allow us to avoid delays due to shipping and supply chain issues and pursue a simple, quicker path,” Shapiro said.

After that, a replacement bridge will be built next to it to reroute traffic while crews excavate the fill to restore the exit ramp, officials said.

The Biden administration is pledging its aid as the collapse snarls traffic in Philadelphia while the summer travel season starts. It has upended hundreds of thousands of morning commutes, disrupted countless businesses and forced trucking companies to find different routes.

Demolition of both the northbound and southbound lanes in the overpass was expected to finish Thursday. Trucks hauling glass aggregate could start arriving the same day and will have a state police escort, officials said.

The company supplying the glass aggregate, AeroAggregates of North America, has a production site just south of Philadelphia along the Delaware River. There, it mills glass bottles and jars diverted from landfills into a powder and heats it into a foam to produce small, lightweight nuggets that are gray and look like rocks — but are as light as Styrofoam, said CEO Archie Filshill.

Each one is about an inch or inch-and-a-half wide.

Filshill estimated that it will take about 100 box-truck loads to haul about 10,000 cubic yards (7,600 cubic meters) of the glass nuggets required for the I-95 project. The total weight is around 2,000 tons, a fraction of the weight of regular sand or dirt, meaning that it will take many fewer trucks to bring it to the site, Filshill said.

PennDOT was the first to use his company’s product after he began making it in 2017, and it is now approved for use by 23 state transportation departments around the country, Filshill said. AeroAggregates will divert material bound for other, less urgent projects to the I-95 project, he said.

The disruption is likely raise the cost of consumer goods because truckers must now travel longer routes, U.S. Transportation Secretary Pete Buttigieg said.

Of the 160,000 vehicles a day that travel that section, 8% are trucks, Buttigieg said.

Police say the driver died in the accident. The Philadelphia medical examiner identified him Tuesday night as Nathan Moody, 53.

State police officials said the trucking company had contacted them and has been cooperating, but declined to identify the company or say whether it was properly licensed for hauling gasoline.

Authorities say the driver was headed northbound on his way to deliver fuel to a convenience store when the truck lost control on a curving off-ramp, landing on its side and rupturing the tank.