Thermite weld failure resulting from persistent track conditions led to August 2017 derailment near Dominion City, Manitoba
Winnipeg, Manitoba, 24 July 2018 – In its investigation report (R17W0175) released today, the Transportation Safety Board of Canada (TSB) found that a thermite weld failure resulted in a Canadian Pacific Railway (CP) freight train derailment near Dominion City, Manitoba.
In the afternoon of 11 August 2017, a CP unit freight train was proceeding northward on the Emerson Subdivision when 22 covered hopper cars loaded with corn derailed while exiting a bridge over the Roseau River, near Dominion City, Manitoba. There were no injuries, and no product or rolling stock entered the waterway.
The investigation determined that the train derailed when a thermite weld, which joins two pieces of rail, failed under the train. The thermite weld fracture displayed "finning", which occurred when molten metal leaked from the casting mould and did not fully fuse with the rail. The thermite welding process had been completed in 2008. Also, due to the presence of multiple persistent and recurring geometry defects and track conditions, the rail in the vicinity of the thermite weld had been experiencing higher stresses during normal train operations. With the repeated tensile forces due to normal passing of each wheel of a train, the finning became the origin site of the fracture that led to the brittle failure of the thermite weld.
Although CP had been monitoring the priority surface defects in accordance with the federal Track Safety Rules and its Red Book requirements, the thermite weld failed before the priority defects reached a level that required immediate repair. If track geometry priority defects are not identified, monitored, and mitigated in a timely manner, further track structure degradation can occur, increasing the risk of derailments.
Following the accident, CP completed a rail replacement program on the Emerson Subdivision, installing about 5000 feet of continuous welded rail.
The TSB is an independent agency that investigates air, marine, pipeline, and rail transportation occurrences. Its sole aim is the advancement of transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability.
For more information, contact:
Transportation Safety Board of Canada