A string of train accidents has put North America’s surging crude-by-rail business under heavy scrutiny. Canadian and U.S. regulators are pressing for changes to improve safety on the transport of oil-by-rail.

On Wednesday, the Railway Supply Institute (RSI), a lobbying group that represents tank car manufacturers, owners and lessors, revised its recommendations on train car safety standards, following the derailment and explosion in North Dakota late last year of tank cars carrying Bakken oil.

“The accident woke us all up to how this crude oil is different,” said Tom Simpson, president of the institute.

Train cars known as DOT-111s are at the heart of the recent growth in crude-by-rail shipments. Last year they ferried more than 780,000 barrels of oil a day, or about 10 percent of U.S. production, according to the Association of American Railroads (AAR).

Yet railroads, shippers and regulators had long recognized that DOT-111s, which also carry ethanol, often fail during accidents. The cars are more likely to spill their hazardous cargo and catch fire, according to documents dating back to the early 1990s, when the U.S. National Transportation Safety Board (NTSB) noted their repeated failure.

March 2011 - AAR submitted a petition (P-1577) to the U.S. Department of Transportation with design standards that would ensure these train cars could survive accidents without releasing hazardous materials.

The petition made recommendations on many aspects of tank car design, from the material for their outer shells to protective shields and covers for “top fittings” through which liquid cargo is loaded and unloaded.

August 2011 - The AAR went a step further and issued a circular (CPC 1232) that required the adoption of these standards for all cars ordered after October 2011 that would carry crude oil and ethanol.

However, AAR’s recommendations did not apply to the existing fleet of tank cars that were carrying the same hazardous cargo. The industry balked because of the high cost of retrofits and the weight the new design could add to the cars.

July 2013 - An unattended freight train carrying oil from the Bakken shale in North Dakota derailed and exploded in Lac Megantic, Quebec, killing 47 people and decimating much of the small town.

September 2013 - The U.S. Pipeline and Hazardous Materials Safety Administration (PHMSA) issued a rulemaking document to revise its hazardous materials regulations as they apply to shipping crude by rail. The document, called an Advance Notice of Proposed Rulemaking, was the regulator’s first step to revise its existing rules on DOT-111 cars. Besides outlining eight industry petitions and four NTSB recommendations, it solicited comments from interested parties.

The comment period on the PHMSA’s rule making document ended on Dec. 5.

In response, the railroads called for even more stringent standards than those in effect since 2011. Less likely to shoulder the costs, they stressed the need to retrofit or phase out all cars that do not meet those standards.

The Railway Supply Institute (RSI) initially agreed to some of the retrofits AAR suggested but said owners should be able to modify, repurpose or retire cars over a 10-year period. The institute estimates only a third of the nearly 39,000 DOT-111 tank cars that carry crude oil meet the Association of Railroad’s 2011 standards.

On behalf of oil producers and shippers, the American Petroleum Institute (API) requested more studies into retrofit options before final rules are in place.

January 2014 - Secretary of Transportation Anthony Foxx held a meeting with the railroads and shippers which resulted in commitments to consider and address issues related to tank car safety, train speeds and rail inspections, among others, within 30 days.

Following that discussion, RSI proposed stricter safety requirements on new tank cars in a letter submitted to the Secretary of Transportation on Wednesday, essentially agreeing with the railroad’s stringent requirements from November last year.