Sharon Jobson, 50, of Glencoe, Ontario, was served with the $500,000 lawsuit from CN Rail Tuesday, the Toronto Star reported.
She has until July 29, the two-year anniversary of the collision that killed her son, John, who was 22 at the time, to respond to the suit.
On July 29, 2011, the young man was driving when he collided with a Via train at a track crossing near Glencoe. He was airlifted to a hospital where he died six days later.
Six people on the train, which was carrying 116 passengers, suffered minor injuries, and the locomotive and all four coaches derailed, said a Transportation Safety Board report on the incident released last year.
The lawsuit alleges John Jobson was "wholly responsible" for all damages, including track repair and the "bottleneck of rail traffic" caused by the crash. The lawsuit cites the TSB investigation that found the young man had not stopped at a stop sign near the track.
"He created a situation of danger ... [and] had a history of failing to stop at this crossing," the lawsuit said.
Jobson's mother was named the defendant in the suit because she, as his executor, is his legal representative. Before being notified of the lawsuit, she had thought the impending installation of control lights and gates at the railroad crossing meant a measure of closure for her.
"I think everyone thought it was a good ending to a tragic story. This is just really a shock to everyone," Sharon Jobson said, adding she is waiting for her lawyer to return from vacation next week to decide what her next move will be.
CN Rail spokesman Mark Hallman said: "As the matter is subject to litigation, CN has no comment."
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