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Derailments May Increase as ‘Sun Kinks’ Buckle Tracks

In a warming world, the U.S. could see its cities inundated with water, its power grids threatened by intense storms, its forests devastated by wildfire and insect infestations, and its coastlines washed away by storm surges.

Climate change also threatens roads, pipelines, power lines and rail lines in ways that may not be quite as in-your-face as the stark images of homes washed away on a hurricane-eroded beach. Bridges and highways can be weakened or destroyed in floods. Power lines can be burned in wildfires and damaged in major storms. Roads and airport runways are vulnerable to extreme heat, which can soften and deteriorate asphalt.

Examples of railroad track buckling from a report on the issue from the National Transportation Library.
Credit: U.S. DOT

You can add ‘sun kinks,’ or railways that buckle in extreme heat, causing derailments, to the list of things that are already taking a toll on U.S. transportation, a problem that figures to grow significantly as the U.S. warms.

As average U.S. temperatures warm between 3°F and more than 9°F by the end of the century, depending on how greenhouse gas emissions are curtailed or not in the coming years, the waves of extreme heat the country is likely to experience could bend and buckle rails into what experts call "sun kinks." Intense heat expands the metal, curving and misaligning rails that become a danger to the trains gliding over them.

Considering the increasing amount of hazardous materials and number of passengers being transported by rail in the U.S., that could have disastrous consequences.

Passenger railroads saw a 55 percent increase in ridership between 1997 and 2012, with little slowdown expected, according to the Brookings Institution. Freight railroads are likely to see a 45 percent increase between 2012 and 2040, according to the Association of American Railroads. Railroads are currently seeing a giant increase in the amount of some hazardous materials they carry. Because of a hydraulic fracturing boom, crude oil shipments by rail spiked from 9,500 carloads in 2009 to nearly 400,000 carloads in 2013, AAR data show.

When anything goes wrong on the rails, it’s big news even without the help of climate change. Whether it’s a Metro North Railroad passenger train going off the rails in New York City or tanker trains carrying volatile Bakken shale crude oil derailing and exploding, major railroad accidents kill people and destroy property.

Climate change could make moving all those passengers and freight more challenging if it throws a sun kink into the rails.

Extreme heat and cold in a changing climate affect the stability of railroad tracks and can make them prone to buckling and lead to an increase in future derailments, said Andrew Kish, an independent railroad track stability consultant and rail buckling expert who is retired from the Volpe National Transportation System Center at the U.S. Department of Transportation.

Sun kinks have already caused more than 2,100 train derailments in the U.S. over the past 40 years, or about 50 derailments a year, on average.

Sun kinks and other track buckling incidents are among the costliest the rail industry deals with today, with damage running roughly $1 million per derailment, excluding injuries, fatalities and evacuations, Kish said.

The heat waves that scorched much of the U.S. in 2012 — the hottest year on record in the continental U.S. — and the sun kinks they created caused enough derailments that the Federal Railroad Administration (FRA) issued a special safety advisory that summer warning railroads that they should be sure to inspect buckling-prone sections of track. 

Blaming “the unusually high and prolonged record-breaking temperatures” that affected much of the U.S. that summer, the advisory detailed four major train derailments that resulted from sun kinks within the span of about two weeks.

On July 4, 2012, a BNSF Railway coal train crew noticed a sunk kink in tracks near Pendleton, Texas. The crew attempted to stop, but couldn’t before 43 loaded coal cars derailed. The same day in Northbrook, Ill., a sun kink caused 31 loaded coal cars on a Union Pacific Railroad train to derail on a trestle, destroying the bridge and falling onto the roadway below, killing two people.

Another BNSF coal train, also with 31 loaded cars, derailed as it was passing through Mesa, Wash., on July 2, 2012 because of a sun kink, and on June 23 a sun kink caused a Union Pacific coal train to derail in Wyoming’s Powder River Basin.

Despite the record heat, the number of sun kink-related derailments in 2012 was 29, down from the 46 in 2011. There were 14 such derailments in 2013, Federal Railroad Administration data show, a drop the agency attributes to the safety requirements it laid forth in its 2012 safety alert.

A University of Colorado study published in April assessing the impacts of climate change on the Navajo Reservation in the Southwest said climate change-related sun kinks are a major concern for the Navajo Nation because derailments could lead to the disruption of coal production there.

Virginia Burkett, a U.S. Geological Survey scientist who co-authored a 2008 study on climate change’s impact to transportation systems on the Gulf Coast, said last week that an average temperature change of 2 or 3°F in the Gulf Coast region could have a significant effect on train tracks buckling, causing more derailments.

“Yes, you would anticipate more widespread or frequent incidents of track buckling as the temperature rises,” she said, adding that more train derailments will occur only if railroads do not find ways to adapt.

Both passenger and freight railroads have seen increases in use with little slowdown expected.
Credit: Simon J. Brady/Flickr

The four largest U.S. freight railroads — CSX, Norfolk Southern, Union Pacific and BNSF — either declined to comment for this story or did not return requests for comment.

Track buckling in extreme heat is difficult to detect ahead of time because it can happen suddenly and without warning, Kish said.

“Look, if a train derails carrying coal, no big deal,” he said, because coal trains are unlikely to cause significant harm to others nearby when they go off tracks. “But if you dump a train with hazmat (hazardous materials) or liquid nitrogen or crude oil, it starts burning. It’s a more catastrophic event.”

That was the case with several recent derailments involving trains carrying North Dakota Bakken shale crude oil exploding violently. No recent crude oil train derailments have been attributed to sun kinks.

Bakken crude oil was found to be more volatile than oil extracted elsewhere, forcing the USDOT to issue an emergency order on May 7 requiring all railroads carrying Bakken crude oil to notify state emergency responders about the operations of those trains in their states.

The USDOT and the Federal Railroad Administration (FRA) declined to comment on how climate change may affect rail stability.

The administration’s 2012 safety advisory has helped reduce the number of sun kink-related derailments in the U.S., and the USDOT is working with the University of California-San Diego to develop devices that enable railroads to monitor rail temperatures, said FRA spokesman Michael Cole.

But Kish said any reliable technology that can accurately monitor train track stability and warn trains of damage ahead is still too early in the development stage to be deployed anytime soon. 

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By Dave (Basking Ridge, NJ 07920)
on May 27th, 2014

I think this is more of an infrastructure problem that is exacerbated by climate change - as opposed to a difficult-to-avoid-if-it-happens climate change problem such as massive sea level rise engulfing a coastal city or town that can’t very well be picked up and moved out of the way.

Rail track buckles or kinks in hot weather if it is insufficiently restrained from doing so. And in extreme conditions, past and future, it is a known and predictable problem as discussed here. However, not wishing to directly contradict Kish, but sensing technology is in fact available for rail temperature and rail strain. I am not affiliated with these companies nor am I recommending their particular products in any way, but just to drive the point, here are a couple of commercial examples I easily retrieved in a quick search:

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By alchemist from bristol
on May 27th, 2014

“Climate change puts us at risk of extreme weather that costs hundreds of billions every year.”

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By Mary Brown
on May 28th, 2014

Please post some scientific evidence that extreme weather events have actually increased.  I haven’t seen any actual data that supports this assertion.

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By Dave (Basking Ridge, NJ 07920)
on May 29th, 2014

That’s a great and highly pertinent question. The hard-nosed statistical evidence that I am aware of is certainly quite convincing in the case of the current significant increase in the global frequency of temperature extremes. For instance, this quite readable piece: cites data for a 5 fold increase in the global frequency of record breaking hot months over the period 1880 to 2010.

From that same strict statistical point of view, the evidence still seems more debatable in the case of extreme precipitation events, namely droughts and floods. Certainly there is also a lot of debate about this in view of the US situation, events elsewhere like Australia, the unusual recent floods in Europe and the UK and so on. In this case, I think one has to consider the data trends and view the cluster of such events thoughtfully in the light of climate science and corresponding analyses that often describe clear components of climate change that favored or tilted the odds towards an increased likelihood, against the ever present background of noise from normal climate variability.

At the other extreme end of the likelihood scale come the much rarer weather events. Where fundamentally rare events are concerned there is, and will continue to be for the relevant future, necessarily an absence of sufficient, high quality, modern data to determine significant changes in frequency patterns either way (frequency increased, about the same or decreased) for purely statistical reasons.

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By Donald Campbell (Dodgeville/Wisconsin/53533)
on May 31st, 2014

Although I do not know of any formal statistical data on pavement blow ups, a process somewhat like that for railroad kinks, numerous reports from 2012-2014 suggest a significant increase. Portland cement concrete is well known for its thermal expansion, and the problem is likely to become more frequent, given forecasts that this will be a temperature- record setting summer. Go slow and be vigilant.  See:

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By Charles Westmoreland (Houston/Texas/77074)
on May 27th, 2014

I see the train companies are ashamed to comment. Lack of contingency plans, I’m getting my bicycle ready, won’t be caught off guard.

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By Anonymous (Buena Park, CA 90620)
on May 27th, 2014

I wonder if there were fewer sun-kinks in the rail tracks back before the rail roads switched to solid tracks?

Seems to me that a solid rail line has less ability to harmlessly expand and/or shrink than a line made up of many individuals links, which can have a small gap between each one. I remember the clickety klack of the old rail tracks, and they weren’t all that bad.

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By Paddy Shaffer (Dublin, Ohio, 43016)
on May 28th, 2014

I found another train issue.  I am an artist and was out taking pictures of flowering spring trees recently.  I found a train track on a curve with great trees.  As I took my pictures I noticed almost every spike was sticking out of the train track by several inches.  I photographed the tracks and was quite concerned.  I called the guys who are responsible for the four rail lines.  I talked with two men.  I wondered if our extremely cold winter was popping the steel stakes our with expansion and contraction.  I was told that they had more issues with it from the super cold winter.  And i was told that in three days they would send someone to look.  It looked so dangerous to me that no train should have passed on that track until it was fixed.  The health of the wood under the tracks that those spikes are driven into was not good either.  this was on the Camp Chase line, right next to Darby Creek.
I am in central Ohio, and Fracking has hit this state.  So yes all that toxic material is here on our trains.  My name is Paddy Shaffer and I uploaded those photos to my website at Fine Art America.  They are in the folder titled “Contemporary History”.  Take a look.  This is really sloppy train track maintenance, and they were unaware until the artist called them.

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By Jacob (Vineyard, UT, 84058)
on May 29th, 2014

This is hilarious.  This feels almost word-for-word ripped from a satire by which was intended to make fun of climate disaster predictions.

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By Alvin Kaline (San Diego, CA)
on May 29th, 2014

Trains can be a major help in reducing the pollution of greenhouse gases which have increase 50% in just 10 years.  I’ve seen charts that show that temperatures reach over 100 degrees three times more often now than just a couple of decades ago.  This threat of splitting rails is a serious setback

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By MrBadExample (Brooklyn, New York, 11230)
on May 30th, 2014

Such temperature swings are going to do more damage to the asphalt than to train tracks—rail is much easier to repair than all those miles of interstate, and probably easier to mitigate. If we’re at the point where we can’t ship things by rail due to constant warping of steel tracks, we’re going to have bigger problems than derailments. we’re going to have problems growing food and avoiding massive droughts.

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By peter joseph (94960)
on May 31st, 2014

Everybody loves the sound of a train in the distance,
Everybody thinks it’s true.—Paul Simon

Maybe after a few more disastrous derailments due to buckling tracks, everybody will think climate change is true. This also seems an opportunity for someone in their garage to come up with a fix.

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By jim adams (louisa/va/23093)
on June 12th, 2014

Here’s a photo link from 2013 of heat kinking.

It’s real, it’s serious.  And it’s just what rails do when temperatures get into the triple digits. This, i believe is only in the 115 -120 degree range. Once it kinks, it doesn’t unkink. The rails have to be replaced.

We have rails built all across the US to 1940 thru 1960 temperature standards, from back when 120 degrees was unthinkable. They are going thru and replacing kinks wherever they find them—and the easiest way to find them is for a train to go over something like this at 60 mph with a couple hundred cars carrying oil.

I’m wondering if other metal structures—like bridges and power line towers—kink like rails. Does any one know???

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By Jack Johnson (90210)
on June 14th, 2014

Jim Adams, it is possible for many steel structures to fail as a result of temperature increase. However, this sort of sunlight-induced slender buckling behavior we see here is unique to railroad tracks, because of the exceptional slenderness of railroad track pieces (which leads to Euler buckling). I-beams in bridges and skyscrapers tend to be much more stout and have much more lateral restraint by comparison. To make a fully-restrained I-beam fail through heat-induced buckling would require something along the lines of a fire.

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