One of the iconic sensory experiences of riding a train is actually the sound of originality. As steel railroad tracks heat up, they grow. For every 10 degrees Fahrenheit that rises, 1,800 feet of rail expands by more than an inch. That’s why the rails are laid in small gaps, each 30 to 60 feet long.
“The very specific railway noise you hear is – Chuchart… Chuchart… Chuchart… Chuchart… Chuchart “There’s a gap between the rails, and that gap is there for that expansion,” said Dev Niyogi, who studies urban climate extremes at the University of Texas at Austin.
However, in extreme heat, the rails can swell until the sleepers underneath can no longer support them. The rails then become noticeably wavy, forming what is known as a line kink. This is a serious hazard for trains that can derail on misaligned tracks. In extreme cases, the tracks can buckle violently, changing from straight lines to bizarre curves. Almost immediately. So when the weather is too hot, rail services slow down their trains as a precaution, providing less mechanical energy that could lead to buckling. For example, Amtrak Speed limit is 80 miles per hour. When the rail temperature reached 140 degrees. That was partly the reason. After the Amtrak delay On the Northeast Corridor between Washington, D.C. and Boston during a severe heat wave last month. (Amtrak did not respond to multiple requests for comment for this story.)
As extreme heat intensifies, more tracks will become sun-twisted, disrupting commuter rail service and reducing carbon emissions and slowing global warming. A 2019 study estimated that the U.S. rail network could suffer between $25 billion and $45 billion in additional delay costs by 2100. That scenario assumes greenhouse gas emissions decline over the next two decades.
Compared to trees falling on tracks, blocking traffic, or tripping switches, heat is a much bigger and more difficult problem for rail operators to deal with. “The impacts can be huge because heat tends to be localized,” said Jacob Helman, one of the authors of the 2019 study and a senior climate consultant at Resilient Analytics, which provides infrastructure vulnerability assessments. “You can have five days that affect the entire Northeast Corridor.”
As climate change drives Hotter and longer As the heat intensifies, companies are reassessing their operations and adopting new technologies. Railroads already use remote sensors to monitor rail temperatures, but they’re getting more sophisticated as the heat intensifies. For example, they’re using computer modeling to figure out how to make track more resistant to buckling, among other steps. “Using advanced sensors, satellite imaging and AI, the industry is implementing new ways to continuously monitor track conditions and respond to potential hazards,” said Scott Cummings, vice president of research and innovation at MxV Rail, a subsidiary of the Association of American Railroads.
Extreme weather conditions cause Amtrak trains to be canceled, creating a climate advantage.
While the gap in the rails reduces the problem of buckling, it also causes wear on both the rails and the cars as the train wheels roll over each gap. That’s why railroads have been deploying “continuous welded rail,” or CWR—track sections that stretch a quarter of a mile or more—for decades. CWR is made up of concrete sleepers (a strip under the rails that used to be made of wood) that are held together by pouring gravel between them. “Everything’s a lot more rigid,” says Daniel Pike, a rail expert at Sensonic, a maker of train safety technology in the U.K. “There’s a lot more mass to hold everything in place.”
Railroads also adapt their tracks to specific climates. By laying continuous welded rail on days when conditions are right, crews prepare for local highs and lows. “The track is laid and anchored at what’s called the ‘neutral temperature,’ which is the average temperature of the rail,” says Farshid Vahedifar, a professor of civil and environmental engineering at Tufts University who studies the impacts of climate change on infrastructure. “This keeps the rail stable even when temperatures change.” As local temperatures rise, railroads may decide to lay track on hot days to prepare for increasingly extreme heat. (However, rails can shrink and crack when they get cold in the winter.)
Another intervention is Paint the rails whiteThe steel reflects a significant amount of solar energy. “It sounds crazy,” Pike said. “It works.” It’s labor-intensive. The paint wears and gets dirty over time, so it has to be reapplied over and over, but a track-mounted machine can do the job quickly.
A new technology called distributed acoustic sensing uses fiber-optic cables running along the tracks to “listen” for defects. Disturbances in the tracks cause optical devices to shake, changing the way light passes through them. These are analyzed by special devices to determine if a rockfall has hit the tracks or a crack has developed in the rail. Each type of disturbance has its own unique signal.
On the track It heats up and expands.Fiber already listens for “thermal pops.” Pike said that in theory, Sensonic’s technology could detect the unique ground vibrations associated with buckling. They just need data to train the algorithms on what to listen for. Perhaps they could manually heat a test track to induce solar buckling. “We’ve already produced rockfall, landslide sensors, and they’re looking for ground vibrations,” Pike said. “So I can imagine. I can’t promise, but I think we’ll tune them to detect that.”
If railroads could get better data on buckling susceptibility—say, specific track temperatures across a wide area rather than relying on inferences from local temperatures—they could make more precise decisions about how much to slow down trains as a preventive measure. That could avoid delays, keep commuters from having to return to their cars, save railroads money, and make trains safer overall. “You can make more informed decisions about speed commands,” says Resilient Analytics’ Hellman. “Maybe they don’t need to go 40 mph. Maybe they need to go 10 mph. Maybe they don’t need to go at all.”
