Survey crews in boats look over tanker cars as workers...

Survey crews in boats look over tanker cars as workers remove damaged tanker cars along the tracks where several CSX tanker cars carrying crude oil derailed and caught fire along the James River near downtown Lynchburg, Va., Thursday, May 1, 2014. Virginia state officials were still trying Thursday to determine the environmental impact of the train derailment. (AP Photo/Steve Helber) Credit: AP

Trains laden with crude oil that have derailed and exploded in towns across the country are an urgent warning that federal regulators need to get a move on to guard against potential disaster.

The Department of Transportation issued an emergency order this month requiring railroads to notify state officials when trains carrying a large amount of crude oil will travel through their states. That heads-up is important for emergency responders. But the DOT should quickly complete tougher regulations for tank cars and speed the replacement or retrofitting of outdated cars prone to rupture in accidents.

The amount of oil moved by rail has soared because of technological advances that make it profitable to extract crude from shale in the Bakken region of North Dakota. Some of the oil is transported by train to East Coast refineries. And much of that goes through the Port of Albany and then south, by barge on the Hudson River or by rail alongside it, skirting New York City en route to New Jersey.

Safety concerns were ignited in July when a train carrying crude derailed and burned in Lac-Mégantic, Quebec, killing 47 people. After that, a train derailed and exploded in Casselton, North Dakota, in December, one month after a similar accident in rural Alabama. A train derailed in Lynchburg, Virginia, last month. No one was injured in those incidents, but areas in Casselton and Lynchburg were evacuated amid flames and billowing black smoke.

Nudged by federal transportation officials, private industry is voluntarily upgrading tank cars by improving valves and fittings and strengthening tanker walls. About half the cars in use by the end of 2015 will be new or retrofitted, according to the Railway Supply Institute, the trade association. But Canada mandated last month that all outdated tank cars there must be replaced or retrofitted within three years. Federal officials here should put the industry on the clock, too.