22 train car derailment in Calgary's Alyth Yard result of coupler knuckle failure: TSB

A Transportation Safety Board of Canada investigation into a 2019 derailment in the Alyth Yard was caused by the failure of a couple knuckle.

The Transportation Safety Board of Canada's investigation into a 2019 derailment in Calgary determined equipment failure caused 22 train cars to derail.

On the morning of Jan. 6, 2019, 56 rail cars disconnected and ran uncontrolled down the emergency track and collided with stationary loaded hopper cars in the Canadian Pacific Railway Alyth Classification Yard in southeast Calgary.

The impact of the collision caused the derailment of 22 cars and a small amount of fertilizer pellets spilled. No injuries were reported as a result of the crash.

The investigation into the derailment determined found a knuckle — the jaw that allows two cars to securely connect when fastened with a locking pin — on one of the cars that was being switched failed while the cut of 75 cars was moving.

Fatigue cracking was located in the knuckle near the pin bore. TSB investigators say the weakness was likely due to a manufacturing deficiency, but the crack was likely overlooked during the last detailed inspection, conducted two months prior.

The 2019 derailment prompted Canadian Pacific Railway to install a fixed designated emergency track at the Alyth Yard for all switching operations, install retarders to slow cars during an emergency, increase the number of cars with air brakes and introduce limits on tonnage during switching.