Q&A: How did an I-95 overpass collapse in Pennsylvania?

Collapses like the one on I-95 in Philadelphia aren't unheard of, but they're rare
Rebuilding a bridge can be a lengthy and involved process
Preventing crashes might be more effective than fireproofing roads

Updated: Jun 13, 2023 / 05:11 PM CDT

This image provided by the Office of Emergency Management shows firefighters standing near the collapsed part of I-95 in Philadelphia, Sunday, June 11, 2023. The elevated section of Interstate 95 has collapsed early Sunday after a vehicle caught fire, closing the main north-south highway on the East Coast and threatening to upend travel in parts of the densely populated Northeast. (Office of Emergency Management via AP)

(NewsNation) — A major highway in Philadelphia could take months to repair after a portion of Interstate 95 collapsed on Sunday.

The situation began when a tanker truck carrying more than 8,000 gallons of fuel crashed and caught fire underneath Interstate 95. Part of the overpass collapsed from the blaze, significantly disrupting traffic.

One body was discovered amid the wreckage. Officials haven’t released the person’s identity or a possible cause of death.

NewsNation spoke with Joseph Schofer, professor emeritus of civil and environmental engineering at Northwestern University, about the collapse, how it happened, and what the process of rebuilding might entail.

The following interview has been edited for clarity and brevity.

NewsNation: How can a truck fire lead to a road collapse?

Schofer: It’s really simple. The material melts. You had a tank truck that is reported to have been carrying 8,500 gallons of gasoline. It’s not like fire on your stove. It is an immense and intense fire that gets to the melting point of steel. And that bridge was made up of a series of steel beams that were longitudinal beams going the same direction as the roadway, and they provided the primary support.

It’s not hot enough and it’s not intense enough that it’s going to reduce those beams to a liquid that’s going to pile up underneath the bridge. It’s going to soften them. And that means they don’t have the strength to carry the highway, and so they fall down.

NewsNation: Should we be building fireproof roads then?

Schofer: My opinion is no, because of how often this has happened.

You want to do speed management. I’d rather not try to fireproof all my bridges on the extremely remote possibility that we’ll see this kind of event. I’d rather find ways to manage speed on a ramp like that, so maybe the next truck that turns over, say it’s a truck with a container of appliances on it, there won’t be a fire, but there’ll be some disruption.

I’d really rather try to control the traffic than to prevent my bridges from melting.

NewsNation: Videos show people driving on the road as soon as 15 minutes before it collapsed. Was that hazardous?

Schofer: Think about it as cooking on the stove. If you’re trying to boil water, for example, you run the heat on your stove up to a high level but for a long time, you can put your finger in it because it takes a while to heat up.

Those beams are long, they’re big, they’re heavy, and it takes some time for them to get to the point where they start to soften. I would say people continued to drive across it because they had no idea what was going on. With all due respect to humanity, people tend to figure that they’re invulnerable. In a case like that, arguably, if there were some way to control the traffic, you would really want to stop the traffic from going over it — not just because of the risk of failure to the structure, but because of the risk of the smoke and the fumes.

NewsNation: Pennsylvania Gov. Josh Shapiro said rebuilding the bridge could take several months. Why might a project like that take so long and what goes into it?

Schofer: First of all, the ground conditions have to be right. The abutments have to be in good shape, or you have to rebuild them. The abutments are the big concrete pieces at either end that carry the weight of the beams. … I’m guessing six to nine beams, 100 feet long.

You’re going to have to find them and they may not be local, or you may have to have them built from scratch from steel.

So you have to get the beams, bring them to the site, put them in place, secure them in place, and then you have to build a road on top of it. And that takes some time.

NewsNation: Is it possible for it to take less time than expected?

Schofer: In Oakland, a ramp — not a mainline roadway, but still a very significant piece of highway — was replaced and opened in 26 days. They did it with some really clever management strategies. One of the things they did was, when they put the job out for bids, they asked the contractor to commit to an opening date. And the deal was that every day that they opened sooner than the opening date, they got $200,000 and every day they opened later than the open date, they lost $200,000.

Pennsylvania DOT is one of the better departments of transportation. They’re clever people. They could do a pretty good job with this if they put their resources into it. It’s possible to respond quickly. The risk is you get balled up in contracting and permitting and stuff like that. But too many eyes are looking at this. I think that it’s likely to move quickly.