U.S. transportation officials on Thursday pressed for companies to come up with safer ways to transport oil on the nation’s rail lines following some explosive accidents as crude trains proliferate across North America.

After a closed-door meeting with oil and railroad executives in Washington, D.C., Transportation Secretary Anthony Foxx said the industry agreed to make voluntary changes aimed at accident prevention within the next 30 days.

Topping the list are plans to analyze the risks of oil trains that in recent years began passing regularly through major metropolitan areas across the U.S., Foxx said. The results could be used to alter some routes, government officials said. Railroads also will consider where oil trains could be slowed down, to lessen the potential danger in areas that pose the greatest threat to public safety.

“The industry, if they are motivated, can undertake preventative steps that will enhance the safety of the movement of these materials across the country,” Foxx said.

The Obama administration is under increased pressure to take action after fiery accidents over the past seven months in North Dakota, Quebec, Alabama and New Brunswick.

But a safety advocate said the proposed measures fail to address a crucial and longstanding problem: defects in many of the tank cars used to haul crude.

“Just moving the problem around is not solving it,” said Karen Darch, president of the village of Barrington, Ill., and co-chair of a coalition of local officials who have pushed for rail safety enhancements. “If you did that, you are creating too high a risk for the area where (oil trains) might be rerouted.”

The accidents to date have revealed significant gaps in federal oversight of the rail industry, and emergency officials in cities and towns across the U.S. have said they would be ill-prepared to handle another derailment.

Under current rules, shipments of most hazardous liquids including oil do not have to undergo the type of risk studies that were proposed Thursday. Those studies are limited to a handful of radioactive, explosive and highly-toxic chemicals.

The rapid expansion of crude-by-rail has been fueled by booming U.S. production of shale oil, particularly in the Bakken oil patch of North Dakota and Montana. Trains hauling 3 million gallons of crude per shipment to refineries go through hundreds of towns and dozens of cities, from Chicago and Kansas City, to Philadelphia and Seattle.