The U.S. Department of Transportation said Tuesday it adopted new measures aimed at securing unattended freight trains in response to oil train accidents.

The Department of Transportation's Federal Railroad Administration issued a new proposal aimed at strengthening rules on unattended freight trains. The rules are part of a series of federal procedures outlined in the wake of the deadly 2013 derailment in Lac-Megantic, Quebec.

"This rulemaking will solidify our existing securement regulations and provide additional safeguards against the rolling of unattended freight trains, especially those carrying hazardous materials," Federal Railroad Administrator Joseph Szabo said in a statement.

At least 40 people were killed in Lac-Megantic, Quebec, in the derailment of a train carrying tankers of crude oil from North Dakota to Canadian refineries. Montreal, Maine and Atlantic Railway blamed the air brakes on the locomotive for the accident.

Canadian Transport Minister Lisa Raitt announced new regulations in April aimed at increasing safety on the Canadian rail system. The measure from regulator Transport Canada started with an order to remove around 5,000 tanker cars designated DOT-111 from service almost immediately.

A 200-page proposal from the Department of Transportation calls for the elimination of older rail cars designated DOT 111 for shipment of flammable liquid, "including most Bakken crude oil."

The new proposal would prevent trains carrying certain specified hazardous materials from being left unattended.

"Safety is our top priority," U.S. Transportation Secretary Anthony Foxx said in a statement. "Today's action is only the latest in more than two dozen steps we have taken in the last year to further safeguard communities along train routes that carry crude oil and other flammable liquids."