According to the TSB rail occurrence report, 80 freight cars rolled away slowly for approximately 750 feet (about 230 metres) at the Alyth yard.
No one was hurt, and the train remained on the track as it was brought under control after it rolled away.
The TSB said most of the freight cars on the 9,500-tonne train were loaded, but none was carrying dangerous or explosive goods at the time.
The safety of freight rail in Canadian communities re-emerged as a concern after a runaway train carrying crude oil smashed into downtown Lac-Mégantic, Que., killing 47 people and destroying half of the downtown core in 2013.
Calgary inner-city freight tracks have had several derailment incidents over the years. In 2016, there was a derailment in Alyth yard that was dubbed a human error issue. At the time, Coun. Gian-Carlo Carra said he gets one or two calls a month from CP about trains coming off the track.
The Transportation Safety Board is looking into an incident in which 80 unmanned freight cars rolled more than 200 metres at Calgary’s Alyth train yard.
There was another derailment in the same area back in 2013 as several cars carrying flammable liquids came off the tracks. The train was headed northbound out of the train yard.
Krepski said there was no derailment and no injuries were reported in relation to the incident, adding none of the cars were carrying hazardous materials.
In the wake of the Lac-Mégantic disaster, the TSB made several recommendations for better safety practices, including that railways be required to install physical defences to prevent runaway equipment.
Last June, a CN train with 72 rail cars and two locomotive engines rolled uncontrolled from the MacMillan Yard in Vaughan, Ont. The runaway train travelled at speeds of up to 50 km/h for five kilometres before it stopped under its own power.
No injuries were reported in either derailment, but more than 180 metres of track was destroyed in the 2016 incident.
The incident prompted calls for Transport Canada to update training standards for employees in safety-critical positions.
Incidents of runaway trains have increased by 10 per cent since 2013, according to a report released by the TSB earlier this year.
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File: A Canadian Pacific Railway employee walks along the side of a locomotive in a marshalling yard in Calgary, Wednesday, May 16, 2012.
The Transportation Safety Board is investigating after 80 uncontrolled rail cars rolled a quarter kilometre along a track at one of Canadian Pacific Railway’s main marshaling yards in Canada.
TSB said the movement of the train — weighing over 9,500 tonnes — didn’t cause any derailments or injuries. Most of the freight cars were loaded when the train rolled away, but there were no dangerous or explosive goods on board.
In July of 2013, 47 people were killed when a runaway train derailed and exploded in downtown Lac-Mégantic, Que..
A TSB investigation later concluded 18 factors led to the disaster, including poor training, mechanical problems and sloppy safety oversight.
In June, the TSB called on Transport Canada to modernize training and qualification rules for railway employees after another runaway train incident in 2016 near Toronto.
In that case, the board found automatic brakes had not been engaged by two employees assembling a train which contained flammable liquid.
READ MORE: TSB calls for update to railway employee training, qualification rules after runaway train incident near Toronto