Via Rail says it will assist the Transportation Safety Board in its ongoing investigation into a deadly derailment west of Toronto last weekend that was caused by excessive speed.

TSB investigator Tom Griffith revealed Thursday that  investigators had determined that the Via train that derailed Sunday afternoon in Burlington, Ont., was going four times faster than it should have been when it entered a crossover to change tracks.

The locomotive crashed into a building after the derailment, killing three Via engineers and injuring dozens of passengers.

"While we know the excess speed caused the derailment, this is not the end of the investigation," Griffith told a morning news conference in Richmond Hill, north of Toronto. "It's only the beginning."

Why are TSB rail reports done in miles?

The Transportation Safety Board of Canada reports railway-related incidents in miles because the railway industry runs on the imperial system, not the metric system.

Both the Canadian and American systems are set up this way – the distances between points on the tracks and speeds are always listed in miles.

All Canadian trains are also equipped with speedometers and data recorders that read speed in miles per hour.

Hours later, a Via spokesperson said the rail company is just as eager as the TSB to get to the bottom of what happened.

Malcolm Andrews told CBC News that Via "will continue to offer every possible assistance to the TSB in the days and weeks ahead."

According to the TSB, the train was travelling 67 miles per hour (108 km/h) while changing tracks. But the speed limit for changing tracks in the area that train was passing through is 15 mph, or 24 km/h.

Investigators say the brakes were not applied before the train travelling from the Niagara Region to Toronto crashed.

Griffith said the safety board is not out to lay blame in its investigation but to find out the factors behind the derailment.

"No crew sets out to have an accident. Sadly, this crew paid the ultimate price — they lost their lives," he said.

No voice recordings available

Griffith also said the investigation will be made more challenging by the fact that trains are not equipped with voice recorders, something that the Transportation Safety Board has long said should be mandatory.

mi-300-tom-griffith-cbc

Transportation Safety Board investigator Tom Griffith said Thursday the investigation into Sunday's fatal Via Rail derailment is not over. 'This is only the beginning,' he said. (CBC)

If the TSB knew what the engineers on Via Rail train No. 92 were saying, investigators would be able to understand the decisions the crew made "leading up to this accident," Griffith said.

When investigators finish the initial part of their investigation, Griffith said, the TSB "will begin a thorough analysis of the information gathered."

That will include trying to find out why the train was travelling so fast as it changed tracks, as well as examining all the equipment, system and human factors that "may have influenced the crew’s performance."

Later Thursday, MP Olivia Chow, the NDP transportation critic, said it's necessary to make voice recorders mandatory on trains.

Had voice recorders been installed on the Via train that derailed, investigators would be able to know "precisely what happened," she told reporters.

She also called for the federal government to install so-called "positive train control" systems, which have become mandatory in the United States.

This technology is capable of automatically slowing down overspeeding trains, an innovation that Chow said could help prevent the type of tragedy that occurred in Burlington.

Chow also urged the federal government to back away from planned cuts to Via Rail, which is a Crown corporation that operates national rail service on behalf of the government.

A subsequent news release from Chow said the federal government "has cut $400 million from the Via Rail budget, and reduced funding to the Transport Safety Programs."

She said that money could be used to provide additional training to staff or to improve safety.

2nd class action launched

Meanwhile, a second proposed class-action lawsuit has been launched against Via.

Toronto law firms Koskie Minsky and Howie Sacks & Henry began the class action Wednesday on behalf of passenger David Carmichael. It seeks compensation for passengers who were aboard the train as well as their family members.

Toronto law firm Falconer Charney and Windsor, Ont.-based Sutts, Strosberg are also pursuing a class action.

Lawyer Ted Charney told CBC News on Thursday afternoon that his firm has been contacted by "approximately half of the injured passengers" from Sunday’s crash.

Charney said the class action his firm is pursuing is not yet certified. Class actions must be approved by a court before they can proceed.

Sutts, Strosberg handled a class action in a 1999 Via derailment in Thamesville, Ont., that killed two crew members and injured 77 passengers and crew. The company settled and paid damages.

With files from The Canadian Press