Was I-95 collapse preventable? Engineering expert explains how the disaster happened

PHILADELPHIA - Plumes of jet black smoke and raging flames fill the skies as large concrete slabs of concrete come crumbling down.

That was the scene on Interstate 95 in Philadelphia Sunday morning as an overpass of the critical roadway collapsed after a tanker fire erupted just feet below.

The devastating collapse has caused major concerns for commuters and residents, leaving several questions unanswered: how did it happen; was it preventable; can the bridge be re-built?

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Amir Yaghoob Farnam, an engineering professor at Drexel University, stopped by Good Philadelphia Monday to break crown the collapse, and answer some of those questions.

The engineering expert says after analyzing photos and videos, the collapse was likely  the result of two things that just don't mix well - heat and steel.

Farnam says the I-95 overpass was constructed with concrete reinforced by girders made of steel, which is very susceptible to heat.

"Because of extreme heat, steel can lose 40 to 50 percent of its strength," he explained.

Heat from the tanker fire below made it impossible for the bridge to carry its load, according to Farnam, who says this incident reminds him of the World Trade Center collapse.

"It was also a heat problem," he said. "Because the aircraft tore off all the fire-proofing the 911 incident happened."

When asked if the collapse was preventable? Farnam responded that while most buildings have fire codes, outdoor structures do not - something he says engineers should look into to prevent such disasters.

"Maybe we have to re-visit our fire codes," he said. "Maybe put some component of fire-proofing for bridges."

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So how long will it take to re-build the busy interstate, and get back to normal traffic flow in and out of Philadelphia?

Farnams says most bridges take a few years to build, but with the right allocation of resources, he believes the I-95 overpass could be ready in a few months to a year.