No Margin for Error

“Clearly, the heads and shells of DOT-111 tank cars…can almost always be expected to breach in derailments that involve pileups or multiple car-to-car impacts.” — National Transportation Safety Board, June 19, 2009.

Much of the oil traveling by train to the profusion of new oil-by-rail terminals is shipped in what one Chicago-area leader called the “Ford Pinto of railroad cars.” These are the soda-can shaped tank cars, DOT-111s, built to standards in effect as recently as 2011 that have a “high incidence of failure during accidents.” If used to ship crude oil, their design flaws pretty much guarantee that a serious train derailment will lead to oil spills or massive explosions.

One summer night in 2013, a rail accident involving DOT-111s resulted in a catastrophic explosion that killed 47 people in a small town in Quebec. In the months that followed, DOT-111s carrying oil unleashed towering explosions in Alabama, North Dakota, and New Brunswick.

These mishaps were not accidents, so much as they were the logical consequence of a sea change in the way that we transport crude oil. A few years ago, a sudden oil boom from shale geologies, such as the Bakken formation of western North Dakota, caught almost everyone by surprise. With few good options for moving the abundant new found oil to market, companies turned to railroads in a big way: shipments of crude oil by rail spiked, and then spiked again.

Yet shippers are moving oil largely in the old DOT-111 tank cars that for more than 20 years we’ve known are unsafe. In fact, since 1991, the National Transportation Safety Board (NTSB) has issued several crash investigation and safety recommendation reports involving tank cars documenting the inadequacies of the DOT-111 standard.

Things came to a head after a high profile collision in 2009 when a slow moving train composed of DOT-111 cars hauling ethanol derailed at a road-crossing in Cherry Valley, Illinois. The resulting fireball fatally burned a passenger and seriously injured three others in vehicles waiting at the crossing. Local officials had to evacuate residents within a half-mile of the incident.

A tank car carrying ethanol involved in the Cherry Valley derailment showing head (tank car end ) failure lying next to burned automobile. Arrow points to head failure. (Credit: NTSB)

In its subsequent report on the Cherry Valley explosion, the NTSB once again documented the inability of DOT-111s to withstand the forces of accidents even when traveling at low speeds. Investigators ticked off a long list of known problems: the thinness of the DOT-111 metal shell, lack of shielding for tank ends, weak housings for top fittings, tanks that don’t separate from rail car frames during a crash causing them to rip open, outlet valves that open when handles get caught by objects during a crash, and bottom outlet valves that are difficult to protect. (Here is a summary presentation of their DOT-111 findings.) The flaws were so numerous and so severe that the agency urged their owners to retrofit all existing tank cars carrying ethanol and crude oil.

Tank head punctures in two derailed Cherry Valley tank cars (outlined with white paint). (Credit: Federal Railroad Administration)

The NTSB recommendations were largely ignored. Tank cars are regulated not by the NTSB but by another government body: the US Pipeline and Hazardous Material Safety Administration (PHMSA) based on standards developed by a private industry group, the American Association of Railroads. (Transport Canada also plays a role in regulatory development.) After the Cherry Valley incident, industry agreed to new standards to increase the crashworthiness of the tank cars, but only for those ordered after October 2011.

So today, oil trains are mostly composed of the older, flawed DOT-111 tank cars. According to the railroad industry, 92,000 DOT-111 tank cars are used to move flammable liquids.

Yet simply adding new tank cars to the mix of unsafe cars doesn’t work, according to the NTSB, because the “safety benefits [are] not realized if old and new tank cars are commingled.” In other words, if a unit train with old and new tank cars derails, the older DOT-111s will almost certainly breach and explode taking out the newer DOT-111s as well.

Plus, even the newer DOT-111s with thicker shells and shielded ends still have an Achilles Heel: bottom outlet valves “which have been prone to failure in derailment accidents.” During derailment when a tank car skids along the ground, the bottom outlet valve’s operating levers are bent and pulled causing the valve to open, or the valve is sheared off all together. In the Cherry Valley derailment, for example, bottom outlet valves in three tank cars opened and released most, if not all, of the ethanol from those cars. The NTSB found that the bottom outlet valve handle breakaway design in use “has been shown to be of limited effectiveness in preventing product releases from bottom outlets” and that existing standards and regulations for the protection of bottom outlet valves on tank cars “are insufficient to ensure that the valves remain closed during accidents.”

It’s a risk that has been recognized for many years. In fact, based on NTSB recommendations, members of the Chemical Manufacturers’ Association, in the early 1990s voluntarily upgraded the tank cars hauling hazardous chemicals (DOT-105s and DOT-112s) to eliminate bottom outlet valves because of their inherent danger. But crude oil, even the notoriously combustible oil from the Bakken region, need not be moved in these safer tank cars.

Bent valve handle and exposed and partially open bottom outlet valve on a Cherry Valley derailment tank car. (Credit: Federal Railroad Administration)

Bottom outlet valves may be the issue to watch. If new oil-by-rail facilities support only tank cars that can be unloaded by a bottom outlet valve, they will guarantee the presence of a needlessly dangerous design for oil trains.

After each oil train derailment, the railroad industry has pointed out that only a tiny percentage of all rail shipments of hazardous materials result in a release caused by a train accident. These industry statistics are at least partially bogus, as EarthFix reporter Tony Shick demonstrated, but in a sense it doesn’t matter.

With DOT-111 tank cars carrying volatile liquids, any accident rate greater than zero is too high.

To eliminate the risk of a catastrophic explosion, every trip hauling Bakken crude or ethanol has to be perfect. The tracks can never be tampered with; no auto or truck can ever stall in a crossing (or be left on the track maliciously); no mix ups in communication can ever occur; no mudslide can hit a train. There is no margin for error. Because if a train with older DOT-111 tank cars derails and piles up, or if multiple car-to-car impacts ensue, the tank cars will “almost always” be breached. Even with newer DOT-111 tank cars, the risk is not reduced if they are mixed in with the older version. And a train composed solely of newer tank cars still has failure-prone bottom outlet valves on each and every tank car.

There is a fix for all this: temporarily decommission the outdated DOT-111s pending their upgrade, and run oil only in new or retrofitted tank cars without bottom outlet valves. In the next post, we’ll explain why this hasn’t happened—and who’s behind it.

Rich Feldman is a researcher and transportation energy consultant in Seattle.