'All the parts of this one lined up in the worst way,' says transit union president

City officials said Friday they’re reviewing the safety measures linked to its compressed natural gas transit bus fleet, one of which burst into flames Thursday following a collision with another city bus, leaving three dead and 16 injured.

City police said the collision between two buses in the 800 block of Saddletowne Circle N.E., ignited the CNG tanks on one of them.

“Within seconds, the fire intensified resulting in an explosion and significant fire inside the bus,” police said in a press release.

Video taken of the incident shows columns of flame shooting from the roof of the stricken bus.

In a statement Friday, Calgary Transit said all of those CNG buses are subject to regular inspection, maintenance and safety checks. The agency was trying to determine what went wrong Thursday.

“We will be working closely with the investigators to understand the circumstances surrounding the incident and will conduct a review of our CNG operations to ensure any additional safety measures required are put in place,” they said.

“Calgary Transit will share more information as it becomes available.”

Calgary considers itself a leader in employing CNG buses, with the city citing its 44,300 sq.-ft. Stoney Transit Facility as the largest such refuelling complex on the continent and one of the biggest in the world.

It has a capacity to house 470 of the 40-foot buses.

According to the City of Calgary’s website, 347 of its fleet of 40-foot buses — 44 per cent of its fleet — is currently powered by CNG.

That’s slated to rise to half the fleet, or 399 buses, sometime next year in an ongoing initiative to replace Calgary Transit’s aging diesel buses as part of its vehicle diversification strategy.

Those vehicles have lower fuel and maintenance costs while reducing greenhouse gas emissions by 20 per cent and nitrogen oxide output by 95 per cent, says the city.

“Since their introduction in 2014 our CNG buses have helped us reduce our total bus fleet CO₂ emissions by approximately 5,650,000 kilograms. (That’s the CO₂ emissions equivalent to consuming about 2.4 million litres of gasoline),” says the city.

Quebec-based Nova Bus, which supplies Calgary with its CNG transit fleet, declined to be interviewed citing an ongoing investigation.

But in a statement, its spokesman said they’re offering their co-operation in that investigation.

“We are in contact with Calgary Transit to better understand the circumstances surrounding the incident,” said Christos Kritsidimas, the company’s vice-president of legal affairs and external communications.

“It would be premature to speculate on the cause before a thorough investigation has been completed.”

The head of the union representing Calgary Transit drivers said it’s watching the investigation closely, hoping it results in assurances of safety.

He also said such a tragedy shouldn’t have happened.

“We don’t believe there should be a stage where the system could fail to this level and look forward to finding out what transpired and ensure (any safety shortcomings are) not an acceptable part of the design,” said Mike Mahar, president of the Amalgamated Transit Union Local 583.

“We’ve had a number of bad accidents but all the parts of this one lined up in the worst way.”

In August 2025, Calgary Transit announced it was purchasing 120 new electric buses, thanks to funding support from a previous federal government grant.

The Canadian-made Nova LFSe+ electric buses from longtime supplier Nova Bus were to replace some aging diesel-fuelled vehicles and strengthen service reliability, the city said.

Under the previous Justin Trudeau government, federal ministers announced a $325-million grant for the City of Calgary in June 2023 to aid in the purchase of 259 electric buses.

In line with federal targets, the city is aiming to decarbonize its transit system by 2050. Calgary Transit is in the midst of an almost half-billion-dollar fleet transition.

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