Engineers Determine Cause of Fallen Overhead Wire Near Crowfoot Station
Calgary Transit has determined what caused the overhead catenary wire to fall last week near Crowfoot Station.
The root cause was a breakdown in the carbon contact strip on top of the pantograph of the middle car of the CTrain involved in the incident. (A pantograph is the jointed framework on top of the train that conveys an electrical current to the train from overhead contact wires.)
With the train’s carbon contact strip partially missing, the overhead wire was rubbing on the bare metal strip of the pantograph, causing electrical arcing which cut through the strip as the train headed northwest to Crowfoot Station.
This weakening of the pantograph head, along with the pressure from pantograph springs pushing constantly up, eventually caused the pantograph head to buckle upwards and protrude slightly above the contact wire.
This buckled portion of the pantograph head struck overhead wire support arms just before Crowfoot station, pulling on the wire and misaligning the wire with the track. This caused the other two train pantographs on the same CTrain to get tangled with the wire and ultimately pulled the wiring down in the area of the Crowfoot Station track switches.
Calgary Transit has removed seven CTrain cars that have the same carbon contact strip technology from service for further inspection. This does not affect normal CTrain service.
Calgary Transit is also reviewing and ramping up its pantograph inspection process, including the investigation of a system to perform automated visual inspections of each pantograph while CTrains are in service.
Following the damage last Tuesday, Calgary Transit continued to provide service between Crowfoot and Dalhousie Stations using shuttle buses and some trains while repairs were made. Crowfoot Station resumed normal service on Sunday.
Calgary Transit thanks customers for their patience.
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