The National Transportation Safety Board (NTSB) expressed growing concern Thursday that accidents involving oil trains can cause "major loss of life," and recommended that they be rerouted where possible to avoid populated areas.

The safety board's proposal, a direct response to last July's oil train disaster in Quebec, reverberates in the Twin Cities, where 100-car crude oil trains have become a common occurrence.

But diverting oil tankers away from cities, especially historic rail hubs such as Minneapolis and St. Paul, represents a daunting challenge because most major tracks pass through urban areas.

"The main trunk lines were all built to connect major populated areas — New York to Boston, Minneapolis to Chicago — and trying to shunt them onto a branch line that may not have sufficient capability to handle these heavy trains just may not be possible," said Harry Giles, managing principal of Arlington, Va.-based consulting firm PetroStorTech.

The NTSB said crude oil should get the same regulatory treatment as other hazardous substances like chlorine. Railroads are required to reroute those trains, if feasible, to less-populated areas.

The NTSB, in recommendations issued in tandem with Canada's safety agency, also called on regulators and railroads to improve response plans for worst-case crashes such as the one in Lac-Mégantic, Quebec, that killed 47 people in July. That response and cleanup has largely been left to Canadian and provincial governments because the small railroad responsible for the accident filed for bankruptcy.

The NTSB said the investigation of that accident found that the crude oil came from 11 North Dakota suppliers, and that its hazard level had been understated on shipping records. The safety board further recommended that shippers and rail carriers be required to test and document the hazard levels of oil.

Railroads now carry more than 10 percent of U.S. oil, up 40-fold in five years, with much of it loaded in North Dakota, which lacks sufficient pipelines to carry its oil. BNSF Railway Co. and Canadian Pacific, whose U.S. headquarters is in Minneapolis, have major operations in North Dakota and transport crude oil through the Twin Cities.

Two more accidents involving North Dakota oil trains also have produced fiery explosions, adding to concerns about the safety of crude shipments.

An oil train derailed and tankers exploded near Alice­ville, Ala., in November, and on Dec. 30, a BNSF oil train crashed near Casselton, N.D., sending up a cloud of burning petroleum that forced the evacuation of 1,200 people. No one was hurt in either incident.

The Association of American Railroads, the industry's trade group, said it agrees with the safety board's recommendations.

"[T]hey align with our previous calls for increased federal tank car safety standards" and other measures, the group said. BNSF and Canadian Pacific also pledged to work with regulators, communities and others to enhance rail safety.

Federal regulators are separately considering proposals to require the nation's fleet of oil tank cars to be upgraded with thicker steel and other features to reduce the risk of punctures. These and other possible regulations also have implications for the ethanol industry, which has long relied on tank cars to transport fuel.

Sen. Amy Klobuchar, D-Minn., who serves on the Senate Transportation Committee and has asked the chairman for a hearing on rail safety, said the new NTSB report "underscores the need to strengthen our rail infrastructure and ensure the safety of communities and residents living along rail routes."

Yet the NTSB's recommendation to divert trains away from populated areas also was met with doubt.

'No way around Twin Cities'

In Coon Rapids, a city crossed by two BNSF lines, City Manager Steve Gatlin said he's reserving judgment on the recommendations. "It sounds like a positive step, but I don't know that rerouting is practical. The railroad runs right through the center of the community," he said.

"There is no way around the Twin Cities," added Stephen Johnson, a New Brighton railroad enthusiast who has watched the growing number of oil trains traveling through the state. "The tracks were laid out years ago. There are multiple routes out of the Twin Cities, but the trains all come through northeast Minneapolis."

Giles, who formerly headed a petroleum industry trade group, said the challenge of diverting trains is even greater on the East Coast, where much of the crude-by-rail is headed. "If you look at a nighttime picture of the East Coast from space, it is just a blaze of light," he said. "How are you going to avoid that?"

In the Twin Cities, BNSF and Canadian Pacific declined to say whether they divert other hazardous cargoes such as chlorine or anhydrous ammonia outside the metro area. Both companies cited post-9/11 security concerns over the disclosure of such information.

The NTSB, in its safety recommendation, said it "is concerned that major loss of life, property damage, and environmental consequences can occur when large volumes of crude oil or other flammable materials are on a single train ... as seen in the Lac-Mégantic accident."

NTSB Chairman Deborah A.P. Hersman said large-scale shipment of crude oil by rail didn't happen 10 years ago, and that safety regulations must catch up.

"While this energy boom is good for business, the people and the environment along rail corridors must be protected from harm," she said in a statement.

David Shaffer • 612-673-7090 @ShafferStrib