DARTMOUTH, NS, Sept. 27, 2016 /CNW/ - Citing a combination of track conditions and rail wear as contributing factors, the Transportation Safety Board of Canada (TSB) today released its investigation report (R15M0034) into the April 2015 Canadian National Railway (CN) derailment near Saint-Basile, New Brunswick.
On 17 April 2015, a westbound CN freight train derailed 35 rail cars and one locomotive at Mile 212.8 on the Napadogan Subdivision. The derailment destroyed approximately 900 feet of main track. Twenty of the derailed cars were residue tank cars that had last contained crude oil.
The investigation determined that significant wear on the rail had resulted in the wheel contact shifting outward, which reduced the rail's lateral stability. In addition, as the train was negotiating the curve, track conditions and the curve elevation condition combined to increase lateral forces on the rail, leading to the train's derailment.
The investigation observed that if track gauge is close to maintenance tolerances, it is harder to protect against incremental gauge-widening forces, increasing the risk of derailments. It also highlighted the limited guidance available to track maintenance personnel faced with a combination of track conditions. The TSB notes that there are no clear criteria for addressing combination defects (more than one defect occurring within 100 feet of track) that can pose a threat to safe rail operations, increasing the risk that unsafe combinations of track conditions can be missed or remain unaddressed during track inspections.
In 2014, the transportation of flammable liquids by rail was added to the TSB Watchlist. Based on this investigation and previous ones, recommendations, and other safety communications, the TSB reiterates that flammable liquids must be shipped in more robust tank cars to reduce the likelihood of a dangerous goods release during accidents. Fortunately, in this accident, all the derailed tank cars were residue cars.
Following the occurrence, CN reduced the combined wear limit for 136-pound rail and initiated gauge restraint measurement to enhance its assessment of lateral strength of the track structure.
See the investigation page for more information.
The TSB is an independent agency that investigates marine, pipeline, railway and aviation 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.
SOURCE Transportation Safety Board of Canada
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