Warner and Kaine also urged the department to reach out to local emergency officials in affected communities, such as Lynchburg and Richmond, through which the rail shipments pass from the Midwest to Yorktown, where a transfer terminal is being expanded to handle as many as 800 crude oil trains a year for storage and shipment by barge to East Coast refineries.

"Communication requirements are already in place for pipeline and marine operations, and yet small towns across the country have very little or no knowledge as to the contents and timing of crude oil shipments that move through their communities," the senators said in the letter to Foxx.

The National Transportation Safety Board is investigating the Lynchburg derailment, which involved a "unit train" carrying 105 tanker cars filled with crude oil. The previous week, the NTSB had held a two-day safety forum in Washington that focused on the need to improve the safety features of outmoded tanker cars to prevent them from rupturing and spilling their contents, assess the routes used for hazardous materials shipments and ensure that affected communities have the knowledge and ability to respond to accidents.

The concerns have been longstanding, but greatly intensified after a catastrophic wreck last July in Lac Megantic, Quebec, in which 47 people were killed after an unattended train rolled down a steep grade and derailed in the middle of town, engulfing it in a fire that raged for more than a day before it was extinguished. More than 1.6 million gallons of highly volatile oil was released from 63 tanker cars in the accident.

In January, the NTSB published a series of detailed recommendations after participating in an investigation of the Lac-Megantic accident with the Transportation Safety Board of Canada. The NTSB asked that the Pipeline and Hazardous Materials Safety Administration, a division of the federal transportation department, expand regulatory requirements for route planning of rail shipments of hazardous materials and "where feasible, require rerouting to avoid transportation of such hazardous materials through populated and other sensitive areas."

The board also urged federal officials to revise minimum shipment thresholds for requiring spill response planning and to require rail carriers to provide "comprehensive response plans to effectively provide for the carriers' ability to respond to worst-case discharges resulting from accidents involving unit trains or blocks of tank cars transporting oil and petroleum products."

Finally, the board recommended that shippers be required to test and document the "physical and chemical characteristics of hazardous materials," based on the finding in the Canadian investigation that crude oil transported on the train that wrecked in Lac-Megantic was improperly classified.