Irving Oil Ltd. has announced plans to voluntarily convert its DOT-111 tank railcars to meet higher standards by the end of April.

The company will also ask its suppliers to adhere to the Association of American Railroads (AAR) recommended specifications by the end of the year, president and CEO Paul Browning announced in a statement on Monday.

Rail cars destined for the Irving Oil refinery

These railcars destined for the Irving Oil refinery in Saint John include some of the older DOT-111 model. (Connell Smith/CBC)

The announcement comes less than one month after the Transportation Safety Board (TSB) called for tougher standards for the DOT-111 cars that are widely used in the oil-by-rail industry.

DOT-111 tank cars, called CTC-111A in Canada, were involved in the Lac-Mégantic, Que., train derailment disaster in July 2013 that killed 47 people.​

The train was carrying a shipment of crude oil destined for the Irving Oil refinery in Saint John.

The AAR specifications recommend that DOT-111 railcars built after October 2011 include reinforcements and enhancements that have been reported to reduce the risk of product loss if the railcars are involved in derailments.

"We have made substantial progress in converting our fleet of crude oil railcars to meet this enhanced standard," said Browning, noting 88 per cent of Irving Oil's fleet already complies.

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The railcars full of crude that exploded in Lac-Mégantic, Que., in July were destined for Irving Oil's refinery in Saint John. (CBC)

"In light of the strongly worded recommendation from the TSB in January, we felt it was important to communicate this milestone to the public," he said.

"Safety is paramount to our business, and by taking this voluntary leadership position with our own fleet of railcars we expect to set a standard for the suppliers and marketers who ship crude oil to our facilities to quickly follow our example."

So far, Transport Canada has opted not to order the immediate conversion of the entire Canadian rail fleet, which includes tens of thousands of older model DOT-111 railcars.

Irving Oil officials declined an interview on Monday to provide further information, such as the number of cars involved, whether they're owned or leased, or how much the conversion will cost.

But any of the remaining older-model railcars will be emptied over the next 10 weeks, cleaned and then removed from service, according to the statement.

By April 30, Irving Oil's in-service proprietary DOT-111 rail fleet in Canada and the United States will consist exclusively of railcars built in 2012 and 2013, it said.

Transport Canada officials executed search warrants at the Irving Oil headquarters in Saint John in December as part of the investigation into the Lac-Mégantic investigation.