Environmental groups are suing the U.S. Department of Transportation over the shipment of crude oil in old railroad tank cars they say are too easily punctured or ruptured when derailed, leading to dangerous spills.

The lawsuit, filed Thursday by the Sierra Club, EarthJustice and ForestEthics says the agency failed to respond to a legal petition the groups filed in July. That petition sought an emergency order to prohibit crude oil from the Bakken region of North Dakota and Montana and elsewhere from being carried in older tank cars, known as DOT-111s.

"The Department of Transportation must take immediate action to halt the use of dangerous DOT-111 tank cars which are known to derail and explode when transporting volatile crude, and which have devastated communities across North America,” Devorah Ancel, an attorney for the Sierra Club, said in a statement.

Kevin Thompson, a spokesman with the Department of Transportation, declined to comment, citing the pending litigation.

Since 2008, there have been 10 significant derailments in the U.S. and Canada in which crude oil has spilled from ruptured tank cars. The worst was a runaway oil train that exploded in the Quebec town of Lac-Mégantic a year ago, killing 47 people.

The federal government in late July proposed rules that would phase out tens of thousands of older tank cars that carry crude oil and other highly flammable liquids.

But that process could take several years, and in the meantime, shipments of crude oil in older rail cars are putting small towns and major cities along the rail lines at risk, the groups said.

"That's just far too long given the risks," said Patti Goldman, a lawyer with EarthJustice, which is representing the groups.

Al Jazeera and The Associated Press