OTTAWA — Executives from CN and CP rail told a Commons committee Thursday that safety is a top priority, but some crashes are inevitable given the volume of traffic.

"You can mitigate the risk, but you can't eliminate the risk," Keith Creel, CP's chief operating officer, told reporters following the committee meeting.

The committee has been studying the shipping of dangerous goods since the train derailment and explosion in Lac-Megantic, Que., last summer that killed 47 people and levelled much of the small town's core.

The runaway train was carrying Bakken crude in its DOT 111 cars, which have been deemed unsafe since 1991 but are nonetheless often used to ship dangerous goods through North America.

CN executive vice-president Jim Vena told the committee CN and CP own a combined 240 DOT 111 cars, but that represents a fraction of those currently being used to transport goods — dangerous and otherwise — across the continent.

CN and CP both indicated the oil companies and shippers who own the vast majority of DOT 111 cars should pay to replace them.

On Tuesday, the head of the Transportation Safety Board told the committee the DOT 111s were going only 20 km/h when they crumpled on impact in Lac-Megantic.

NDP MP Mike Sullivan questioned whether a speed of 15 km/h through urban areas might be prudent for DOT 111s carrying potentially explosive materials.

Creel said there could be unintended consequences and a slow a speed would throw off the railways' schedules.

"Maybe it does, but at least it's safe," Sullivan responded.

The government has until April 23 to respond to safety recommendations the Transportation Safety Board released in January.

Asked if her response would include plans for phasing out the DOT 111s, Transport Minister Lisa Raitt replied: "Absolutely, absolutely."