LAC MEGANTIC, QUE. -- Jean Clusiault is having to re-live the horrific train disaster at Lac Mégantic, but he says it's necessary -- he's part of a new class-action lawsuit looking to hold Canadian Pacific railway accountable.

The class action got underway this week and could last up to seven months, with the judge expected to hear from more than 100 witnesses, bringing a new set of answers into what happened in the 2013 catastrophe.

Clusiault's daughter, Kathy Clusiault, was among the 47 people killed. She had just moved to the area.

Her father is still looking for answers, he says, and the next seven months should deliver some of them.

"It makes now eight years that tragedy happens, but for me, I still have my daughter in my mind," he said.

The class action is based on the allegation that CP was ultimately responsible, since it contracted out to a smaller and less reliable railway.

In 2013, a runaway train carrying highly flammable crude oil levelled the town. The class action alleges that CP's decision to run the fuel through Lac Mégantic wasn't necessary and was motivated by profit.

The allegations in the class action have not been tested or proven in court. 

To carry crude from Montreal, the company had other options, said the lawyer representing Clusiault and others in the proposed class action.

"CP carried the crude oil from North Dakota to Montreal," said lawyer Daniel Larochelle.

It was then responsible for the next decision, too, about how to get it to New Brunswick, picking the Montreal Main Atlantic railway.

"They decide to choose [an] old company with old railway with old engine -- MMA, Montreal Main and Atlantic -- and we think that’s big fault for CP," Larochelle said.

Lawyers are representing not just families but insurers and the province in the lawsuit.

The train’s engineer, Tom Harding, was the first witness called. He recounted the night of the disaster.

While acquitted of criminal negligence in a previous trial, he testified once again about how he did not apply sufficient handbrakes when he parked the train.

Clusiault says he's accepted how this part happened.

"I don’t blame him," he said. "It was a poor company -- that’s the reason why."

The federal Transportation Safety Board identified 18 causes for the accident, including poor maintenance and lack of oversight.

The class action should help, but it also won't fully put Clusiault's mind at ease, he said.

"We will have new elements in this trial to have more answers to our questions, but I [am] still thinking and asking for a public commission and inquiry, that’s it," he said.

CTV News reached out to the federal transport minister to see if an inquiry is under consideration but did not receive a response.