Federal regulators are proposing to phase out thousands of older rail tank cars that carry crude oil. It's the government's response to a series of fiery train crashes over the past year, including a runaway oil train that exploded in the Quebec town of Lac-Megantic, killing 47 people.

The Department of Transportation said Wednesday that older DOT-111 tank cars will have to be retrofitted or replaced.

Accident investigators have complained for decades that the cars are too easily punctured or ruptured when derailed, spilling their contents.

On April 30, 17 cars full of crude oil derailed in downtown Lynchburg.  One of three cars that landed in the James River broke open and caught fire.  All the tankers involved in the derailment were DOT-111 models, according to federal investigators.