Federal regulators said Wednesday that they would require railroads and oil shippers to use stronger tank cars to transport crude oil across the nation within two years, offering a speedier timetable than initially expected in response to a spate of derailments and spills involving oil trains over the past year.

The timetable is faster than a similar effort in Canada, which plans to phase out older tank cars within three years.

The proposed rules announced by the Transportation Department offer a wide range of measures to enhance the safety of oil trains, many of which had already been adopted by railroads on a voluntary basis in recent months, such as notifying state emergency responders about train traffic, reducing speed limits or picking the safest route.

After a series of derailments, many local and state officials have expressed concern about the rapid rise of oil-train traffic across the country. Many critics have called for the retiring of older tank cars that have proved vulnerable to puncturing and exploding in a crash. Making things worse, the kind of oil that comes out of the Bakken region -- which includes shale fields in North Dakota and Canada -- is particularly flammable and prone to explosion.

Under the new rules, tank cars used for crude oil, ethanol and other petroleum products would require increased steel shielding and better thermal protection, and would have to be fitted with more crash-resistant valves. Older models that cannot be refitted with these features would have to be retired or used for other purposes.

Transportation officials are still seeking public comment on whether to outfit the new cars with electronically controlled brakes and rollover protection, and whether to use 7/16-inch or 9/16-inch steel. The department said the proposed rules would be open to public comment for 60 days. Final rules are expected by early next year.

The Transportation Department has been working on the new standard for several years. But the rapid development of domestic oil supplies from the Bakken shale region has caught many federal and state officials off guard. Most of that oil is transported by rail, given the lack of pipelines to take the oil to refineries.

The hazards of transporting crude oil by rail were made apparent last year, when an oil train derailed and exploded in Lac-Megantic, Quebec, destroying much of the city center and killing 47 people.

A new tank car design was introduced in 2011 with some enhanced features, but those cars also have been involved in spills -- most recently in May, when an oil train derailed in Lynchburg, Va., and spilled 30,000 gallons of oil into the James River.

About 98,000 tank cars are in service carrying crude oil and ethanol in the United States and Canada, according to the Association of American Railroads. Their design dates to the 1960s, and an overwhelming majority were built before 2011. About 18,000 have been built since then and could be modified if needed, according to industry officials.

Some industry officials point out that phasing out older cars too fast would lead to a shortage in tank cars that might curtail the surging production of oil from the Bakken.

A Section on 07/24/2014