Metro Transit inspects for ‘sun kinks’ during hot summer weather

Published: Jul. 15, 2022 at 6:50 PM CDT
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ST. LOUIS, Mo. (KMOV) - When the temperature hits 93 degrees, Metro Transit sends out teams of special heat inspectors to check the Metrolink tracks. They’re looking for what’s called “sun kinks”, or bends in the tracks from the heat.

When temperatures rise, steel expands and that puts a lot of stress on train tracks. Sometimes tracks can bend or buckle under stress. That reduces the stability of the track and can lead to derailment.

Tiss and Roger Rettig went to the Kirkwood train station on Friday afternoon to pick up a relative who was coming in on an Amtrak train from Kansas City. Like most people, the Rettigs said the summer heat’s impact on train tracks isn’t something they’ve ever considered before.

“I don’t think about it, just get on the train and go,” said Roger Rettig.

Tiss Rettig added, “I want them inspected as much as possible.”

If inspectors find a sun kink in a Metrolink track, they’ll immediately place a speed restriction on the section of track out of an abundance of caution. And then later that night, crews will either realign the track or reset the tension on the tracks based on the temperature.

Despite all the hot days so far this summer in the St. Louis area, inspectors have only found one mild sun kink on the 46 miles of Metrolink tracks.

News 4 reached out to BNSF to ask about heat buckling and inspections. The company said it visually inspects tracks on a regular basis and performs additional inspections during extreme heat conditions.

Additionally, BNSF said a rail detector that uses ultrasonic rays to detect flaws is used across the system and on main lines, as frequently as every 30 to 50 days.

And the company said it uses a track geometry car three times a year that can measure the surface and alignment of a track, among other things.