Giving freight rail tracks a boost

May 15, 2015 by Scott Gordon
Giving freight rail tracks a boost
A booming industry in hydraulic fracturing has presented a new challenge: grains of sand can leak from rail cars, accumulate in rail bed ballast and, during a rainstorm, turn into mushy, track-loosening mud. Credit: Tuncer Edil/UW-Madison

The big chunks of rock—crushed limestone or dolomite that engineers call ballast—that keep railroad tracks in place look like a solid footing even as freight cars rumble overhead.

But temperature and vibration can destabilize ballast over time, keeping it from safely transferring the weight of a loaded train to the soil below, draining water and preventing vegetation from crowding the tracks.

In Wisconsin, a booming industry mining sand used by oil and gas drillers in hydraulic fracturing has presented a new challenge: fine grains of sand can leak from rail cars, accumulate in rail bed ballast and, during a rainstorm, turn into mushy, track-loosening mud.

"Some of these tracks have deteriorated so much that the trains travel at about 10 mph," says Dante Fratta, professor of civil and and geological engineering at the University of Wisconsin-Madison. "You have to lift up the track, remove the ballast, and put in new material. It's very expensive. It's also very expensive to have derailments."

Fratta will spend part of the spring examining these problems along a section of freight track in northern Illinois with colleagues Tuncer Edil, emeritus professor of geological engineering and civil and environmental engineering, and Jim Tinjum, professor of .

While frac sand poses a relatively new challenge in the Midwest, the three researchers hope to bolster the nation's freight rail network against all manner of stresses that cause this particular problem, known as ballast fouling.

The big chunks of rock that keep railroad tracks in place look like a solid footing, but temperature and vibration can destabilize ballast over time. Credit: Tuncer Edil/UW-Madison

Fratta plans to install in a section of track to monitor temperature, deformation and vibration in the ballast, as well as any corresponding deformation in the tracks themselves. Damage and deformation often occur within a small area of the rail bed. Fratta wants operators to have a better handle on how problems arise, giving them a better idea of how to target repairs to rail infrastructure in more cost-effective ways.

Edil is partnering with the soil stabilization and pavement lifting company Uretek to devise a system to inject polyurethane to shore up damaged or potentially weak sections of ballast. Unlike cement, liquid polyurethane is great at seeping into the voids between rocks. And while cement can take weeks or even months to set properly, polyurethane injections can set within 15 minutes.

The group still has to make sure polyurethane injection is the most cost-effective and energy-efficient approach.

"This has to beat the standard way of fixing the problem," Edil says.

Producing less replacement ballast would mean using fewer fossil fuel resources, but making polyurethane also uses energy, so Edil and Uretek have conducted a life cycle analysis to determine whether, in the long run, their process actually reduces greenhouse gas emissions and energy consumption.

Tinjum is coordinating the academic and industry teams involved, ensuring that researchers have crucial access to railroad infrastructure. For obvious reasons, railroad companies don't let just anyone experiment on their tracks, so building relationships and delivering results are important on a project like this.

"Whenever you do something for the first time, you want it to work, because you need that experience and that trust for future development," Tinjum says.

If the engineers' pilot projects pay dividends on the tracks that carry freight out of Wisconsin, the group would like to apply its concepts to other vulnerable points in railway infrastructure.

Railroad tracks take a beating at bridge approaches—where the weight of a train is transferred between surfaces with differing physical properties—and at intersections with roads, where tracks deal with the stress of trains and the weight of other vehicles.

Since injection tools have been previously used to level runways and sidewalks, Tinjum thinks they can translate well into railways.

"The immediate huge application is the remediation or improvement of the capacity of these intersections for them to last longer," he says.

Explore further: Research could boost durability, cut cost of railroad tracks

Related Stories

Research could boost durability, cut cost of railroad tracks

November 21, 2011

Every year, companies that own railroad track across the United States spend millions of dollars maintaining ballast, the crushed rock underneath railroad ties and steel rails. In addition to the high cost, railroads must ...

For Midwesterners, more boxcars mean cleaner air

December 8, 2011

Shifting a fraction of truck-borne freight onto trains would have an outsized impact on air quality in the Midwest, according to researchers at the University of Wisconsin–Madison.

Recommended for you

A not-quite-random walk demystifies the algorithm

December 15, 2017

The algorithm is having a cultural moment. Originally a math and computer science term, algorithms are now used to account for everything from military drone strikes and financial market forecasts to Google search results.

US faces moment of truth on 'net neutrality'

December 14, 2017

The acrimonious battle over "net neutrality" in America comes to a head Thursday with a US agency set to vote to roll back rules enacted two years earlier aimed at preventing a "two-speed" internet.

FCC votes along party lines to end 'net neutrality' (Update)

December 14, 2017

The Federal Communications Commission repealed the Obama-era "net neutrality" rules Thursday, giving internet service providers like Verizon, Comcast and AT&T a free hand to slow or block websites and apps as they see fit ...

The wet road to fast and stable batteries

December 14, 2017

An international team of scientists—including several researchers from the U.S. Department of Energy's (DOE) Argonne National Laboratory—has discovered an anode battery material with superfast charging and stable operation ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet May 15, 2015
Great idea BUT, what about the fact that its basically "plastic". That will grind up in the existing ballast with vibrations from passing train loads placing small to microscopic debris into the earth. With all the "plastic" flotsam in the oceans, do we want to start the same type of "plastic tsunami" around all the thousands of rail lines around the world with something like this? I think its time to rethink this approach until the plastic degradation possibilities are well understood. Using what is essentially plastic for this is sheer lunacy in my opinion.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.