Austin's record-breaking heat wave is melting railroad tracks.
A short stretch of Capital Metro's Red Line warped earlier this month between the Highland and MLK stations — a dangerous situation that if undetected could have caused a derailment.
The ordeal unfolded on a section of the track near Cherrywood Road and Clarkson Avenue on Aug. 4.
An engineer operating a Red Line train with passengers on board had been traveling under 10 miles an hour, a standard procedure along certain sections where the temperature of the tracks can exceed 135 degrees Fahrenheit.
The engineer noticed the warped tracks before crossing them, CapMetro Chief Operating Officer Andy Skabowski said. The engineer called a supervisor to report a suspected "sun kink," industry jargon for tracks warped by extreme heat.
With permission from his supervisor, the engineer slowly drove the train over the kink, "which they are allowed to do and is standard operating procedure," Skabowski said.
The train finished its route. Passengers on later trains had to take buses between stations.
The heavy rail contractor Herzog — with whom CapMetro has a 10-year, $104 million contract — was able to fix the track that night.
This was the first time CapMetro detected a deformed track on the Red Line since Sept. 20, 2021, when a kink was discovered on a section of track nearBlock House Drive in Cedar Park.
Capital Metro's Red Line runs 32 miles with nine stations between Leander and downtown Austin. The transit agency is building new stations at Q2 Stadium and the Uptown ATX development near the Domain.
Freight trains can use CapMetro's commuter rail lines at night. But without the pounding heat from the sun, rail temperatures don't get high enough then to risk warping.
Union Pacific crews have been seen working recently on the tracks along the MoPac Expressway. A Union Pacific spokesperson said the work was regularly scheduled track repair that had nothing to do with tracks warping.
Extreme heat is forcing trains to slow nationwide, including in Dallas, Florida, the San Francisco Bay Area and Washington, D.C.
Slowing trains so engineers can detect buckling is "a prudent practice," said Jim Blaze, a New Jersey-based railroad economist who has analyzed derailments for the Federal Railroad Administration.
The alternative, Blaze said, is to re-weld the track joints to a new preferred rail temperature, which would be "expensive and time consuming."
"Sun kinks are going to be more common as long as the temperatures are higher than you expected when you first laid that rail," he said. "Those temperatures are a little out of whack now."
