Christina Lopez, 72, of Downers Grove died after being ejected from the train because of damage caused by a collision with a box truck in Clarendon Hills.
The lawsuit alleges negligence by Metra, BNSF railroad, the trucking company and the driver involved.
An investigation is still ongoing to determine why the truck was on the tracks.
The NTSB planned to release a preliminary report in two weeks after gathering footage from nearby video cameras as well as witness accounts. The complete investigation could take up to 18 months to complete.
"There's a lot information here, and we want to make sure that we get it right," NTSB vice chairman Bruce Landsberg said.
The family said Lopez was a "tremendous" woman who was retired with three daughters
"We want to get the answers but also more importantly, we want to do our part to help so that no family has to do and go through this tragedy again," Klonowski said. "It didn't have to happen."
Lopez's family said they are still struggling to process the sudden loss.
"It's shock," Klonowski said. "I mean nobody expects this. It's a tragedy that nobody should endure."
Family of Metra crash victim speaks out
Lopez was killed while on her way to see her sister. It was a train ride from Downers Grove that she had taken often without ever thinking twice.
"It was a very routine morning for her, certainly," Klonowski said. "The kids will miss her, the family will miss her. It will be a difficult time but we'll get through it."
Lopez lived in Chicago for most of her life, even working as a maintenance worker at ABC7 for a number of years. She moved to Downers Grove just a few years ago to spend more time with her three daughters and her grandkids.
"She was the glue to the family," Klonowski said.
Residents have complained about the construction at that intersection and some believe that could have stalled the truck on those tracks, leading to this accident.
"From everything I've heard that was an accident waiting to happen," said Steven Jambois, a laywer representing Lopez's family. "The traffic because of the construction at that intersection was so slowed down that people were in harm's way quite frequently."