Long before crude oil and ethanol were transported by railroads in large quantities in minimally reinforced tank cars, other flammable and poisonous materials were riding around the country in the same cars, threatening major cities and waterways.
Federal regulators might be weeks away from issuing new safety guidelines for tank cars carrying flammable liquids, after a series of frightening rail accidents over the past six months.
But the type of general-service tank car involved in recent incidents with crude oil trains in Quebec, Alabama and North Dakota _ the DOT-111-A _ has a poor safety record with hazardous cargoes that goes back decades, raising questions about why it took so long for the railroad industry and its federal regulators to address a problem they knew how to fix.
Other, more specialized types of tank cars received safety upgrades in the 1980s, and the industry's own research shows they were effective at reducing the severity of accidents.
Tank car manufacturers have built new DOT-111A cars to a higher standard since 2011, but the improvements haven't caught up to tens of thousands of older cars.
To be sure, improper railroad operations or defective track cause many accidents involving tank cars. But the National Transportation Safety Board, which makes recommendations but has no regulatory authority, has cited the DOT-111A's deficiencies many times over the years for making accidents worse than they could have been.
"Moving as quickly as possible to upgrade the tank cars is critical," said Peter Goelz, a former managing director of the NTSB who's now a transportation safety consultant. "No one wants to see it happen again."
A review of federal reports and documents going back four decades shows that the DOT-111A tank car factored into a wide range of calamities, including:
- A 1981 rail yard accident that shut down a portion of Newark International Airport and blocked traffic from reaching the Holland Tunnel into Manhattan until a punctured tank car finally burned out its contents of flammable ethylene oxide after 40 hours.
- A 1983 rail yard accident that triggered the evacuation of 9,000 people in Denver when corrosive nitric acid escaped through a puncture in a tank car, forming a large vapor cloud.
- A 1991 derailment _ the worst chemical spill in California history _ that sent a tank car loaded with a toxic pesticide tumbling into the Sacramento River, poisoning a 40-mile stretch of one of the state's most important water supplies and fishing areas.
- A 1992 spill near Superior, Wis., that resulted in the release of benzene into the Nemadji River, leading to the evacuation of 40,000 people in Superior and nearby Duluth, Minn., and the deaths of 16 species of wild animals near the accident site.
- A 2001 derailment midway through a 1.7-mile, century-old rail tunnel beneath downtown Baltimore in which a punctured tank car carrying flammable tripropylene fed a raging fire that burned for five days, ruptured a 40-inch water main and prompted the evacuation of the Camden Yards baseball park.
Many tank cars that were built starting in the 1960s were designed to carry as much cargo as possible, which meant thin shells that could easily puncture or rupture in a derailment. While economical, the designs proved disastrous in a number of horrific incidents involving toxic and flammable gases.
The deaths of numerous railroad workers and emergency responders in the 1970s spurred regulators and the industry to improve the safety of the pressurized tank cars used to transport "all kinds of exotic materials that cause battlefield-like damage," NTSB official Edward Slattery told The Associated Press in 1978.
By the early 1980s, pressurized cars were equipped with puncture-resistant shields, fire-resistant thermal insulation and devices to help the cars stay coupled in derailments, reducing the risk that they could strike and puncture each other.
The non-pressurized DOT-111A, however, was left mostly unaltered. Upgrades probably weren't necessary when the cars were carrying benign products such as corn syrup or vegetable oils, but regulators also allowed the cars to transport flammable and corrosive materials.
In accident after accident over the next three decades, the NTSB repeatedly referred to the cars' shortcomings.
"The inadequacy of the protection provided by DOT-111A tank cars for certain dangerous products has been evident for many years," the NTSB wrote the Federal Railroad Administration in a letter dated July 1, 1991.
