US freight railroads want lawmakers to either provide them with liability limits or eliminate the federal mandate to carry toxic substances.

"The inordinately high risks now shouldered by the railroads must be dramatically reduced through improved safety and the provision of reasonable liability protection," said Edward Hamberger, chief executive of the industry's top trade group, the Association of American Railroads.

Hamberger said the insurance industry is unwilling to cover railroads against risks associated with highly dangerous shipments.

Hazardous materials such as chlorine, ammonia and some resins are important to the operation of many industries and are often or nearly exclusively shipped by freight rail. These goods make up less than 1 percent of total carloads but 50 percent of insurance costs.

"Due to the expense and lack of available coverage, most railroads are only able to insure a fraction of their net worth," LaTourette said. "For a smaller carrier, a single hazmat accident might force the company into bankruptcy."

The Ohio Republican plans to explore new ways of addressing risk exposure for very hazardous commodities. He suggested that Congress could limit liability for accidents, which is done when railroads haul nuclear material.

"Other alternatives might be a federal liability compensation fund, a national (insurance) program or perhaps even a tort cap," LaTourette said.

Some lawmakers have suggested rail and chemical companies strengthen the tankers that carry the most dangerous chemicals. US transportation safety investigators also want railroads to place hazmat tankers toward the rear of a train to minimize potential damage to cars during a derailment.

But LaTourette does not believe cities and towns should be allowed to reroute hazardous materials shipments transported by rail, like local officials in Washington, D.C., would like to do.