CHICAGO (CBS) – More Metra trains are running late – and you can blame the extreme heat of the past few weeks, at least in part.

The commuter rail system missed its monthly goal of 95 percent in June, and retiring deputy executive director George Hardwidge said it’s likely that Metra will miss it this month, as well.

He said extreme heat of the type that blasted the Chicago area over the Independence Day holiday is no easier on rail infrastructure than extreme cold and snow.

“The equipment is stressed. All the infrastructure is stressed. And you do have an increased number of failures, which lead to
delays and sometimes multiple delays,” Hardwidge said.

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In all, Metra recorded 476 delays during the month of June, including 165 signal and switch failures. While Hardwidge could not break down how many were heat-related, he said many could have been because of “sun kinks,” the same type of heat-generated rail misalignment blamed for the Independence Day derailment of a Union Pacific R.R. freight train in Glenview, which killed two people when coal cars piling up collapsed the Shermer Road bridge as they drove beneath it.

The sun kinks on the Metra system were troublesome, but not deadly.

One such kink, on the Metra BNSF service linking Aurora and Chicago, delayed 28 evening rush hour trains. BNSF personnel spotted the kink during an inspection. Hardwidge said the inspections, which routinely take place 34 times a week, were conducted daily and in some locations several times a day.

Track construction, primarily on the BNSF line, also cut into its on-time performance, reducing it to 91.8 percent in June.

Increased inspections and decreased speeds will be prominent among the safety precautions that will resume if the extreme heat returns, Hardwidge said.

He said most riders appear understanding.

“They take that (the added emphasis on safety) for granted, and our riders should take that for granted, but we never do,” he said.