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Extreme heat can warp train tracks

by Diana Zoga

Posted on July 27, 2011 at 9:29 PM

Updated Wednesday, Jul 27 at 10:17 PM


(KMOV) -- When the temperature outside hits 95 degrees, MetroLink deploys it's track inspectors every afternoon to ride the trains and look for trouble spots.

In the past two weeks, the temperature on that tracks has often exceeded 140 degrees in the afternoons. At that temperature, steel expands and caused the railroad tracks to bend. The rough spots known as "sun kinks" and if they go unchecked, they can cause derailments.

Scott Grott, Chief of MetroLink Operations, explained that inspectors ride the trains and can feel the rough spots. Crews go back and mark the spot. If necessary, trains are ordered to slow down over the "sun kinks" and sometimes crews have to return to realign the tracks.

"Every summer we have it. This summer, it seems like it's lasted a little bit longer," said Grott.

"Most of the issues first develop as quality of ride or comfort issue,

but it could get severe enough that it does become a safety issue so we want to be vigilant," added Grott.

So far this summer, MetroLink had to issue a speed restrictions on a patch of track in Washington Park, Illinois until repairs could be made. Train operators are asked to slow down for a short stretch, so the train is delayed less than a minute, according to Grott.

Heat can also affect the overhead electrical lines. The heat can cause them to expand and sag and the train's pantograph (the device on top of the train that connects to the electric lines) can tear them down, causing a disruption in service. MetroLink says a special system of weights detects a sagging line and pulls it down, increasing the tension to avoid a problem. Parts of the MetroLink system require a manual adjustment, according to Grott, so crews check them daily.