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TSB: Unstable Track Subgrade Indicated in 2020 Derailment Near Ignace, Ontario

Written by Kyra Senese, Managing Editor, Railway Track & Structures
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The Transportation Safety Board (TSB) of Canada has released its investigative report (R20W0102) regarding the 2020 derailment of a Canadian Pacific (CP) freight train near Ignace, Ontario.

On May 25, 2020, a CP unit grain train was traveling east at 46 mph on the Ignace Subdivision when 53 hopper cars derailed in Ignace, Ontario, at Mile 12.8, according to a TSB release. As a result, grain was emitted from many cars. There were no hazardous materials involved, and no fires were reported. No one was injured.

The inquiry discovered that the track subgrade (the surface beneath the track) in the vicinity of the incident was soft, saturated peat in a low-drainage location. Its load-bearing capacity was surpassed, resulting in an abrupt subgrade failure and derailment.

The operation of loaded high-capacity rail cars in the unit train created longer periods of cyclic loading, accelerating the deterioration of the inherently unstable track subgrade. Additionally, railway inspection procedures and technologies based on surface observations cannot measure underlying subgrade conditions, increasing the risk that impending subgrade failure will go undetected.

Longer periods of cyclic loading were induced by the running of loaded high-capacity rail cars in the unit train, hastening the deterioration of the inherently unstable track subgrade, according to the TSB. Railway inspection procedures and technologies based on surface observations cannot measure underlying subgrade conditions, increasing the risk that impending subgrade failure will go undetected.

Following the incident, CP made upgrades to the track infrastructure in the derailment vicinity to more evenly distribute track subgrade loading and to compensate for variances in settlement through the derailment area.

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