Calls for full independent investigation into fatal Calgary bus explosion

A mechanical engineer and a transportation and energy system analyst tell CBC News that they want a quick investigation into the bus explosion that killed three people here in Saddle Ridge last week. They say it's important to find out if design or safety regulations need to change. And a warning this story shows the bus exploding. A professor of sustainable fuel systems says what happened in Calgary was unusual. The designs are such and the regulations and the design standards are such that this should not have happened. McTaggart Cowan says he can't speculate on the cause, but he says the collision may have ruptured the bus's compressed natural gas line and then something ignited the fire. Key questions, he says, investigators will need to answer. One will be to try and find what caused the fire to start and then the second one will be why did that explosion, what was that explosion that appeared? Was it a tank rupturing or was it just a buildup of gas? And if it was a tank that ruptured, why did that happen? It's god-awful for the families involved. A Canadian transit research group says there are about 1,000 compressed natural gas buses operating in the country. More than a third of them in Calgary. Josip Petranic says Canadian buses, fuel systems and CNG tanks undergo rigorous testing and must meet strict safety standards. The tanks are really heavily engineered to prevent any kind of cataclysmic event from arising because of a pressure failure or an explosion. They're actually designed even to break proactively when there's, let's say, a collision, and to break to allow for the gas to leak in slow form. McTaggart-Cowan and Petranic say that's what we're seeing here, the pressure release allowing the gas to vent. Unfortunately, they say in the crash, something ignited the fire and explosion. Like it dissipates really, really fast. For it to light on fire, it would have had to pool somewhere, like it would have had to be captured somewhere, and then it would have had to come into contact with a flame. So those things would have had to happen for the natural gas to explode. Calgary Police and the Fire Department are both involved in the investigation, but the area councillor also wants an independent probe. My biggest fear is the biases that go into it. You know, so independent review will be just bias-free and a cold ice review will tell us more than internal one. Calgary police say the investigation is in its early stages as CBC News has confirmed that Transport Canada is assisting with the investigation. Brian Labby, CBC News, Calgary.