- Tens of thousands of older tanker cars used to haul North Dakota crude oil and Midwestern ethanol run a one-in-four risk of leaking if they derail, railroad officials told the National Transportation Safety Board (NTSB) Tuesday.

The failure rate, estimated by the Rail Supply Institute and the American Association of Railroads, illustrates a growing concern for safety that has accompanied skyrocketing shipments of crude oil across the country.

Crude oil shipments originating in the United States have grown from about 6,000 carloads in 2005 to roughly 400,000 in 2013 as the United States has tapped domestic petroleum sources. At the same time, the government has yet to issue new standards for safer tanker construction.

About six North Dakota oil trains per day travel across Minnesota and through the Twin Cities, many of them 100 cars long. Each tank car holds 25,000 to 30,000 gallons of crude oil. Ethanol trains, which pose a similar hazard, move on Union Pacific tracks through the state.

But recent fiery crashes have convinced some policymakers that the threat of derailments like the one that happened in December in North Dakota put the public at unacceptable risk.

“A spate of recent accidents in the United States and Canada [demonstrate] that far too often, safety has been compromised,” NTSB chairwoman Deborah Hersman said.

While the rail industry says it moves 99.9 percent of its crude oil shipments incident-free, industry data show that 46,400 rail cars have been damaged in 29,000 accidents since 1970.


“Taking [older cars] out of the fleet reduces risk,” Robert Fronczak of the Association of American Railroads told the board.

But, he said, eliminating them by attrition alone could take 40 to 50 years.

Setting new standards

The sturdier tank cars being built now are half as likely as the older model to spill contents in a derailment, the rail industry estimates. But car construction standards being discussed by the government could lower the chances of a derailment leak to less than one in 20.

However, the rail supply industry has “to have regulatory certainty” before it commits to major new tanker production and retrofitting of old cars, William Finn of the Railway Supply Institute told the board.

Lee Johnson, representing the American Petroleum Institute, questioned the spill data attributed to older, so-called “legacy cars.” He called the numbers “preliminary.”

Johnson said the oil industry needs to keep shipping oil in the older cars “to move increasing production.” There are not enough of the newer, sturdier tanker cars available to meet oil producers’ demands, especially in North Dakota’s Bakken field, which Johnson said will soon be producing 2 million barrels of oil per day.

Roughly 23,000 older “legacy cars” now carry crude oil, and 29,000 more carry ethanol. The United States may soon have even more crude oil moving in the more vulnerable rail cars because of a surcharge Canada now places on their use. That means railroads may divert newer, sturdier cars to haul oil to Canada.

Retrofitting older legacy cars to make them more leakproof will take years, if not decades, several participants said.

“We don’t want to disrupt the country’s need for the fuel these cars are hauling,” Finn said.

Why the details matter

Meanwhile, a better car design remains the subject of debate.

Greg Saxton, chief engineer of the Greenbrier Cos., one of the country’s four major train car builders, believes in greater tanker wall thickness. “Engineers deal with uncertainty by adding some margin of safety,” he explained to the board.

Others argue that thicker walls add weight and reduce storage space without improving safety.

Wall thickness is probably the biggest sticking point in the tanker safety discussion. The Railway Supply Institute wants a standard width of seven-sixteenths of an inch. The Association of American Railroads wants nine-sixteenths of an inch.

“Crude oil contains a significant amount of dissolved gas,” the railroad association’s Fronczak said. A nine-sixteenth-inch wall will contain the vapor pressure that can build inside a crude oil tanker.

Videos shown Tuesday explained why such minutiae might matter. In one, a train car with a thicker wall withstood the whack of a giant prod traveling 14.7 miles per hour, while a car built to current DOT 111 standards ruptured in a 14 miles-per-hour collision.

Other issues include reinforcing the ends of tanker cars where they are most likely to be struck in a derailment, installing pressure-relief valves on tankers to keep crude oil from exploding in the event of a derailment and applying additional thermal protection to cut the risk of fires.

The NTSB’s Hersman asked Johnson how long he felt the older, more vulnerable cars would be needed to haul crude oil.

When Johnson couldn’t provide a specific time frame, Hersman replied: “You’re not making me feel very optimistic.”