Wooden Ties — Like the Ones that Failed in Penn Station — are Nation's Norm

Monday's derailment at Penn Station created a ripple effect of cancellations and delays as crews spent the week repairing the damage. It was all caused by weak, wooden railroad-ties that split the tracks, causing three NJ Transit cars to come off the rails.

The ties are the cross section of the tracks. And while using wood for them may seem old fashioned, it's used on 90 percent of the rails in the U.S., according to Allan Zarembski, director of the Railroad Safety program at the University of Delaware. 

Zarembski said ties are usually made from hardwood trees, like oak or gum, and tend to last about 35 years, though ties in hot, humid climates have shorter lifespans than those in dryer parts of the country. The ties degrade at different rates.

He said concrete ties, which last about 50 years, are common in Europe, but aren't used much in the U.S. for one simple reason:

"A lot of the decisions regarding wooden versus concrete ties are economic," he said. "Why do Europeans have so many concrete ties? Because wood's expensive over there and if you go through the economic analyses, it turns out concrete is cheaper."

Zarembski is reluctant to recommend concrete ties, however. He said wood works fine, but like any piece of railroad equipment, it has to be regularly inspected. On a given piece of track, there might be one or two bad ties, but it would take about half-a-dozen bad ties to cause a derailment.

"You could've had one really bad tie, two or three marginal ties, and, again making the exact determination when a tie is going to fail is a bit difficult," he said. 

He was surprised by this week's derailment, especially considering how frequently the tracks are inspected. "It sounds like they were relying on visual inspection, which is pretty standard for yards, even busy yards like Penn Station. And it looks like they have misjudged the condition, which is a very usual event," he said.

Zarembski said mainline tracks, which run between towns, often use automated inspection devices.

Amtrak said Thursday that it was aware the section of track needed to be replaced, but it didn't realize it was in imminent danger of failing.

Amtrak CEO Wick Moorman is personally reviewing the engineering and maintenance practices on Amtrak rails.

Federal officials are investigating the two derailments at Penn Station.