01/21/2015 07:30 EST | Updated 03/23/2015 05:59 EDT

Lac-Mégantic derailment: investigators’ conclusion not retained in final report

The Transportation Safety Board did not retain the opinion of expert investigators when compiling its final report into what caused the train derailment and explosion that killed 47 people in July 2013.

Radio-Canada’s Enquête program obtained a copy of the TSB’s initial report. It found that one reason — identified by investigators in the initial report as a contributing factor in the crash — is not given the same importance in the final version.

In the initial report. Transportation Safety Board investigators were of the opinion that the fact the train didn't have a 2-person crew contributed to the accident.

Train engineer Tom Harding was working alone that night. Unsealed documents revealed that handbrakes were insufficiently applied to the 79-railcar train.​

An expert in the field, who asked to remain anonymous, told Radio-Canada that studies show a two-person crew is safer.

“With two people, you double the chances that enough hand brakes and other safety measures are applied,” he said.

TSB not certain one-man crew was a contributing factor

When the TSB’s final report came out, it listed 18 factors that led to the deadly crash — including a weak safety culture at the MM&A, and a lack of oversight from the government agency.

The issue of the one-man crew was reduced to a risk factor — not a contributing factor — in the derailment.

“We could not conclude with certainty whether, yes or no, that would have changed the results that night, said TSB President Kathy Fox.

Although the question of one-man crews was not prominent in the TSB’s final report released last August, Transport Minister Lisa Raitt announced banning one-man crews on trains that are carrying dangerous goods for safety reasons.

“We've established a two-person minimum for locomotive crews,” Raitt said.