U.S. Transportation Secretary Anthony Foxx asked oil-by-rail leaders to create a tank car fit to carry the kinds of fuel involved in recent fiery derailments even as he dodged lawmaker questions about when such a plan would be ready. Rail shipments of oil have been on the rise in regions that lack sufficient pipelines such as North Dakota's Bakken energy patch, where production is nearing 1 million barrels per day and roughly 72 percent of that fuel moves on the tracks. But several accidents saw the rail cargoes explode with surprising force since summer, prompting demands for a tougher tank car to carry the fuel. Foxx said his agency was working hard to come up with a new tank car design. "My target date is as soon as possible," Foxx told a panel of the Senate Appropriations Committee when asked when the new standard would be ready. The Department of Transportation is responsible for mandating a new tank car design, but officials are counting on input from industry. The Association of American Railroads has gathered together oil producers, shippers, tank car manufacturers and others to try to design a tank car that will satisfy regulators. But industry sources say compromise has been difficult among stakeholders with different concerns such as costs and whether an overly bulky model might limit cargoes. Foxx wrote to association President Edward Hamberger on Wednesday, encouraging the industry to continue its work and update officials on progress soon. Officials agree that the workhorse for oil-by-rail deliveries, the model DOT-111, is the wrong container for fuel shipments that are expected to climb in the years ahead. Many shippers are phasing out DOT-111s in favor of a toughened model known as version 1232, but officials have said even that tank car needs design upgrades and a blessing from regulators. "Even the railroad industry and the DOT have been talking about going beyond the 1232," National Transportation Safety Board chair Deborah Hersman told lawmakers. "We think that's wise given the risk here." A design favored by the railroad association would require tank cars to be fitted with pressure relief valves, to sit within a steel jacket and have larger shields at either end to prevent puncture. A further meeting of the tank car panel is scheduled for next week. The Federal Railroad Administration said that it intended to mandate a minimum of two-person crews on most trains. The practice of having more than one crew member is already an industry standard. (Reuters)