The Associated Press

WASHINGTON — Responding to a series of fiery train crashes, the government proposed rules Wednesday that would phase out tens of thousands of older tank cars that carry increasing quantities of crude oil and other highly flammable liquids through America’s towns and cities.

But many details were put off until later as regulators struggle to balance safety against the economic benefits of a fracking boom that has sharply increased U.S. oil production. Among the issues: What type of tank cars will replace those being phased out, how fast will they be allowed to travel and what kind of braking systems will they need?

Accident investigators have complained for decades that older tank cars, known as DOT-111s, are too easily punctured or ruptured, spilling their contents when derailed. Since 2008, there have been 10 significant derailments in the U.S. and Canada in which crude oil has spilled from ruptured tank cars, often igniting and resulting in huge fireballs. The worst was a runaway oil train that exploded in the Quebec town of Lac-Megantic a year ago, killing 47 people.

In Central Oregon, the proposal was welcomed by the Bend Fire Department.

Bill Boos, the department’s deputy chief of fire operations, said Wednesday the proposed rules for safer tanker cars are good news.

“It’s great because they’ve taken a big step toward what they should do,” Boos said.

“As they get into Bend, they slow down because they’re coming through town. Our biggest concern has always been the reinforcement of the tank cars because if something were to happen and they fall over, we want them to be reinforced.”

Boos said he hopes the current federal requirement for railroads to report large shipments of more volatile Bakken oil — a minimum of 1 million gallons of oil, the equivalent of approximately 35 tank cars — can be expanded to cover all oil shipments.

Oregon Sens. Ron Wyden and Jeff Merkley, both Democrats, said on Wednesday the proposed rules are a positive step, but did not go far enough.

Wyden will continue to push for broader notification requirements, his spokesman, Keith Chu, said.

“He is going to put pressure on the Department of Transportation to go further, so that cities like Bend and Baker City and Eugene can have the notification they need to be prepared for these trains,” Chu said on Wednesday.

In a June letter to Department of Transportation Secretary Anthony Foxx, Wyden and Merkley urged him to expand the earlier emergency order requiring railways to notify communities of large shipments of oil from the Bakken region. The senators said Oregon public safety officials should know of all oil-by-rail routes through the state, and they should have the option to access information about all oil shipments, regardless of size or origin.

Chu said much of the oil transported by train through Central Oregon is not covered by the reporting requirement in the emergency order because it does not originate from the Bakken region of western North Dakota, eastern Montana and southern Saskatchewan.

“When it comes to Bend specifically, the Federal Railroad Administration told our office there is non-Bakken crude coming through Bend,” Chu said.

Burlington Northern Santa Fe Railway does ship some oil through Central Oregon, according to a report from the railway that the Office of State Fire Marshal released earlier this month. The document revealed that at least one train traveled through Bend with a large load of Bakken oil in June.

In a statement Wednesday, Wyden said the Department of Transportation’s decision not to expand the current reporting requirement to cover all oil-by-rail shipments “is especially baffling since the DOT’s proposal would classify all oil and ethanol shipments as ‘high-hazard flammable trains,’ yet would only require railroads to provide advance notification to first responders when that oil originates in the Bakken.”

Merkley said the proposed rules fall short. “I am concerned … that the proposed rules fail to provide adequate information to emergency responders and local governments,” Merkley said in a statement.

Having given the proposed restrictions a preliminary review, Michael Lang, conservation director for the Friends of the Columbia Gorge, said he has concerns about the speeds at which oil trains would be allowed to go through towns.

“We will be commenting and will be asking for the strictest restrictions on oil trains to ensure our safety of our communities and environment,” he said. The Portland-based nonprofit focuses on the protection of the Columbia River Gorge.

Lang spotted an oil train in May on tracks along the Deschutes River close to the Columbia River. The train was headed south toward Bend.

Foxx, the U.S. transportation secretary, said he expects his department to complete final regulations before the end of the year. First, the public and affected industries will have an opportunity to comment on the proposal.

“We are at the dawn of a promising time for energy production in this country,” Foxx said. “This is a positive development for our economy and for energy independence, but the responsibilities attached to this production are very serious.”

In a report released along with the rules, the Department of Transportation concluded that oil from the Bakken region of North Dakota and Montana, where fracking methods have created an oil boom, is more volatile than is typical for light, sweet crudes.

The oil industry immediately challenged that conclusion. “The best science and data do not support recent speculation that crude oil from the Bakken presents greater-than-normal transportation risks,” said American Petroleum Institute President and CEO Jack Gerard. “DOT needs to get this right and make sure that its regulations are grounded in facts and sound science, not speculation.”

Rail shipments of crude have skyrocketed from a few thousand carloads a decade ago to 434,000 carloads last year. The Bakken now produces over 1 million barrels per day, and production is increasing.

— Bulletin reporter Hillary Borrud contributed to this story.