Rail cars carrying crude oil that derailed and exploded in North Dakota on Dec. 30 released over 400,000 gallons of oil after 18 tanker cars were punctured, according to a preliminary National Transportation Safety Board report released Monday.
The derailment, near Casselton, N.D., and other recent oil-by-rail accidents have increased political pressure on the Transportation Department to toughen safety regulations for tank cars that carry hazardous materials.
The preliminary NTSB report estimates that the Dec. 30 accident caused $6.1 million in damages. Roughly 1,400 people in the area were temporarily evacuated after the derailment and no injuries were reported. Most of the estimated 400,000 gallons of oil released ignited.
The accident occurred after a train hauling grain derailed, which caused the subsequent collision that derailed the crude oil train that was heading in the opposite direction.
Both trains were travelling below the maximum allowable speed when the derailments occurred, according to the NTSB.
The train cars hauling crude oil were an older model known as DOT-111. Lawmakers from both parties are pressing the Transportation Department to issue rules that would lead to the retrofit or phase out of the tankers.
"The NTSB report shows that 18 of the 20 derailed tank cars were punctured. We need to understand why these tanks are breaching, and the [Transportation Department's] Pipeline and Hazardous Materials Safety Administration needs to expedite its work to release proposed updated standards for rail tanker cars," said Sen. Heidi Heitkamp, D-N.D., in a statement Monday.