Why's That: The Surprising Sophistication of the Railroad Tie | WMUK

Why's That: The Surprising Sophistication of the Railroad Tie

Feb 12, 2021

A pile of old railroad ties near Paterson Street and Graphic Packaging, Inc in Kalamazoo
Credit Sehvilla Mann / WMUK

If you’ve seen a railroad, you’ve seen railroad ties, the beams that brace the track crosswise from underneath. In the US they’re usually made of wood. But when listener Gordon Stewart went abroad, he noticed concrete ties on railroads.

This got him thinking. “Why don’t we use concrete ties in the states, having seen them in Europe and a number of other places and thinking it would be a lot of advantages to them?” he asked.

Advantages like not having to treat the wood with preservatives. Old wood ties can leach toxic chemicals. Gordon had to deal with some on his property.

“In that case I’m stuck with hazardous waste that has to go to a special landfill if you do it right,” he said.

Gordon and I talked to a couple of rail experts. We learned wood ties predominate in the US and that’s likely to continue. But it’s no accident many European railroads use concrete ties. They’re excellent for a certain kind of railroad, one that remains scarce in the US.

“So what is it exactly that railroad ties do?”

Gary Fry heads up research and development at the Transportation Technology Center Incorporated in eastern Colorado. Fry’s company tests railroad technology as part of a public-private partnership.

“The primary purpose of a tie is to keep the rails a very specific distance apart,” Fry told WMUK in a recent virtual interview.

But just how perfect that spacing has to be, that depends. This is where speed comes in.

Fry said the faster a train goes, the more critical it is to nail that distance between the tracks. He said this is like the difference between a roller coaster and a slide on a playground.

“There’s just a lot more control and maintenance requirements for a roller coaster in an amusement park than there is for a slide in a playground because it’s going so much faster,” Fry said.

Most trains in the US are freight trains. They’re the playground slides in Fry’s analogy. He said they travel about 70 miles an hour. The roller coasters are high-speed passenger trains – really high speed, with some traveling almost 200 miles an hour. Europe has a number of them and those high-speed trains need the tracks to fit just right.

Fry said concrete, with its stone-like stability, can hold its shape for decades. That makes it an excellent choice for high-speed rail.

Fry said you could use wood on those railroads. “It just probably, you’d have to replace it more frequently. Because it would begin to degrade to a point that you couldn’t maintain the geometry you needed to maintain as the wood became older and just went through its natural cycle of environmental exposure,” he said.

But Fry added wooden ties work quite well for America’s freight trains. Those trains are slow, but they’re also heavy. They can weigh twice as much as a passenger train and wood can generally take the impact. And in some cases wood ties are more durable than concrete.

Michael Franke is a former vice president and chief engineer of the BNSF railway who now lives near Michigan City.

“Once in a while you’ll have a derailment, where just one wheel comes off the track and it drags for miles sometimes,” he said.

Franke said a dragging wheel can break concrete ties right in half.

“Whereas the wooden tie is more resilient and you’ll get a mark, just a wheel mark down say the middle of the track but the tie itself is still intact.”

Then again, Franke said, concrete ties do better on sharp curves. That’s because rails wear out on curves and have to be replaced. Which means reattaching the rail to the ties – and too much reattaching can ruin a wood tie. Also, Franke said when all other things are equal, concrete ties generally last longer than wooden ones. Which means you don’t have to replace them as often.

“And you want to minimize, on a high speed territory, you want to minimize the amount of time that the track is out of service for maintenance,” he said.

But most railroad ties in the US are wood - more than nine in 10 according to Franke. In many cases they’re cheaper to use, at least in the short term. And Franke added some railroads simply prefer wood. Amtrak says it has about 3,000 concrete ties in Michigan, a tiny fraction of the total. Franke said the market share might grow.

“But by far the greatest number of ties will continue to be wooden, for the foreseeable future, in my belief,” he said.

For that matter, wooden ties – and the problem of disposing of old ones – aren’t unknown in Europe. In one TV news report from France, a reporter walks around a heap of old ties at a railroad station in the western city of Limoges. He says the air reeks of tar and the ties may be leaching chemicals into the groundwater.  

Franke says one place you will see concrete ties is on the Chicago-to-Saint-Louis line used by Amtrak. Our railroad question-asker Gordon Stewart suggested he and I go see them.

“I think some cash should be found for that and we should plan on that trip,” Gordon said.

I told him I would look for this cash.

“Yeah, right, yeah, good luck.”

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