Philadelphia I-95 Bridge Collapse Explained

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I appreciate how many times you managed to vary how you said "A tanker collided with an overpass"

I live just outside Philly. There's one reason that the gridlock didn't occur that isn't getting much coverage. Real-time traffic routing. Turn by turn directions from phones and GPS didn't just blindly offer official detours. They adapted to real traffic in near real time. This let the flow spread out to minimize resistance like water through a maze. Traffic could utilize the entire regional road system to re-levelize.

I really enjoyed the bit where you go over why the bridge repairs can get done so fast (and why other stuff usually doesn't). In just a few words - "fast, good, cheap. pick two."

One element I'm surprised you didn't discuss: A tanker fire is a destructive BEAST. Designing around something like that just seems prohibitively expensive, especially given the rarity and isolated nature of the risk.

I am a truck driver in the Philly area, it was a nightmare and the listed detour was a route(I-676) that is a parking lot on the best of days. I can vouch that the economic effects were pretty crazy.

The same happened in Germany on September 17th, 2020 on the A40 Autobahn. A tanker truck burns out under a bridge. The bridge was then demolished and rebuild. And that in the most populous area with the highest traffic volume. A main railway line runs over the bridge and also had to be closed. The replacement buses for the trains had to drive under the bridge.

Feels good to hear about topics like induced demand and varied transport infrastructure not only from urban planning channels, but from an engineer, even if only in passing.

I love that you and Road Guy Rob are friends! His channel is severely underrated and deserves more attention. Great video, as usual.

Crazy, we just had something similar to this happening just outside of Toronto Ontario, Canada. They deemed that the bridge was okay, so far it's still standing.

Exact same thing happened in Yonkers, NY in 1997. There was a turning lane that looped back under the underpass for I-87 which had been known to be dangerous and a serious risk for decades, but had been left once it was built. One day a tanker truck made the turn and was hit by a car coming down the road that formed the underpass. The truck sprung a leak which quickly turned into a fire, and it destroyed the overpass for I-87. It ended up taking about 5 months to rebuild in an emergency contract, and that turning lane was removed, as there was another not a block away controlled by a light already.

Side note; as a DOT intern, we got a notice about what happened in an email. They mentioned some materials stored under the bridge were flamable and we should be careful to not do that anymore. Hope this little insight may have been helpful

The foamed glass is such a cool material. I was on a project where they used it to fill a rooftop beer garden on an office tower. Guys were hauling giant bags with their hands, but you could walk on it no problem.

tanker trucks, the natural enemy of bridges

Ottawa is currently replacing all of it's highway bridges (and has been for a few years) and the replacement itself usually takes a little over 3 days. The next replacement starts August 10th and is usually live streamed for those interested.

Additional ways to reduce the risk of fire under bridges: 1 Better working conditions for truck drivers. 2 Better maintenance of trucks.

Thanks for boosting Road Guy Rob! I started watching his videos a few months ago, and I like how he gives a balanced, ground view of the urban design and planning stuff and its effects, positive and negative.

A classic instance of a fire on a bridge was Robert Stephenson's historic Britannia Bridge across the Menai Straits from Wales to Anglesey. Finished in 1850, it had twin wrought-iron box girders through which the trains ran. Part of the corrosion proofing was by tarred hessian (we'd never use that today, but it lasted 120 years). 120 years later, it caught fire (kids probably playing with matches). Though the tubes survived, the fire destressed them and impaired their load-carrying ability. The tubes have been replaced with a double deck on steel arches using the original piers and abutments.

I was living in Rouen, France when the bridge took fire (and sadly I was using it everyday to go to work). It was fun seeing the bridge transported by a barge on the river to be repaired in Belgium. It made for some once-in-a-lifetime pictures.

Really glad to hear you mention that increased traffic throughput increasing traffic demand. So much good discussion of civil engineering/city planning has come up recently. Especially on Nebula!