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In rail transport, the U.S. DOT-111 tank car, also known as the CTC-111A in Canada, is a type of non-pressure tank car in common use in North America. Tanks built to this specification must be circular in cross section, with elliptical, formed heads set convex outward. They have a minimum plate thickness of 7⁄16 inches (11.1 mm) and a maximum capacity of 34,500 US gallons (131,000 L; 28,700 imp gal). Tanks may be constructed from carbon steel, aluminum alloy, high alloy steel or nickel plate steel by fusion welding.
Up to 80% of the Canadian fleet, and 69% of U.S. rail tank cars are DOT-111 type. DOT-111A cars are equipped with AAR Type E top and bottom shelf Janney couplers designed to maintain vertical alignment to prevent couplers from overriding and puncturing the tank end frames. Many of these transport a wide spectrum of dangerous goods, including 40,000 cars in dedicated service carrying 219,000 car loads of ethanol fuel annually in the U.S.
Hydraulic fracturing of new wells in the shale oil fields in the interior of North America has rapidly increased use of DOT-111 cars to transport crude oil to existing refineries along the coasts. The Montreal, Maine and Atlantic Railway runaway train in the Lac-Mégantic derailment of 2013 was made up of 72 of these cars, some of which ruptured, releasing explosively their cargo of Bakken formation light crude oil, resulting in a large fire and mass casualty event.
The DOT-111 tank cars are constructed with a draft sill design. Draft sills incorporate the draft gear behind each coupler that is designed to transfer longitudinal draft (tension) and buff (compression) forces throughout the length of a train. The draft sills are attached to steel pads that are attached to the tank. If the cars do not incorporate a continuous center sill extending the entire length of the car, the two draft sills at each end are referred to as stub sills, and the tank carries draft forces between couplers. In this case, reinforcing bars may be extended underneath the tank between the draft sills. Body bolsters and their associated body bolster pads centered above the railcar trucks support the tank and protect it against lateral forces. The draft sill center plate serves as the attachment point between the tank car body and the truck assembly. (See schematic cutaway at right.)
The body bolster pads and front sill pads are attached to the tank with fillet welds. At the rear edge of the front sill pad, a butt weld attaches the front sill pad to the body bolster pad and to the fillet weld attaching the body bolster pad to the tank shell. Fillet welds at the interior and exterior sides of the head brace attach the head brace to the front sill pad, and an exterior fillet weld attaches the head brace to the draft sill. To the rear of the head brace, the draft sill is welded to the front sill pad, body bolster pad, and reinforcing bars.
Because rail cars have no front or rear, for descriptive purposes, the ends of the cars are designated "A" and "B." The B end of the car is the end equipped with the wheel used to manually set the car's hand brakes. The end without the brake wheel is the A end. As trains are assembled, either end of a tank car may be placed in the front or rear position. The tank shells are constructed of several rings welded together, with six rings in a typical configuration. By convention, ring-1 is at the A end, and if there are six rings, ring-6 is at the B end. The tank rings can be welded in a "straight barrel" configuration, or with a "slope bottom" sloping down to a bottom outlet valve at the center of the tank.
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The relevant US regulatory framework is found at 49 CFR Part 179. An overview of "49 CFR Part 179 - SPECIFICATIONS FOR TANK CARS" is available online. while the Means of Containment of the Transport of Dangerous Goods Regulations of Canada is found in Part 5. The US regulations call for the employment DOT-xxx containment standards, where 'x' substitutes to a numeral between 0 and 9, while the Canadian TDG Regulations have latterly a CSA/CGSB-xx.xxx container standard nomenclature, although as noted by Powers, the DOT-111 standard seems to apply in Canada.
A 2013 Senate of Canada committee report proposed mandatory minimum insurance for rail companies. Currently the railway industry lags the pipeline industry in value of mandatory insurance coverage, to a ratio of 1:40.
Railway operators are not required to inform Canadian municipalities about hazardous goods in transit. The 2013 Senate committee (see above) recommended the creation of an online database with information on spills and other incidents from rail cars.
DOT-112 tank cars and DOT-114 tank cars have been required since 1979 under Regulation SOR/79-101 of the Canada Transportation Act for the transportation of gases such as propane, butane, or vinyl chloride. Transportation Safety Board of Canada Railway Investigation Report R94T0029 section 1.13.1 documents DOT-112 tank car and DOT-114 tank car standards: the DOT-111 tank "cars are not considered to provide the same degree of derailment protection against loss of product as the classification 112 and 114 cars, designed to carry flammable gases." DOT-111 tank cars may have been employed in trains such as those of the Lac-Mégantic derailment because crude oil is largely not a gaseous product at standard temperature and pressure.
A report on "The State of Rail Safety in Canada" was commissioned by Transport Canada in 2007. The report contains a 10-year statistical examination of its subject. Section 6 is entitled "Accidents involving dangerous goods". A formal review of the Railway Safety Act was empanelled by the Minister in February 2007. The review, which was tabled in Parliament later that year, has a different take on the subject.
During a number of accident investigations over a period of years, the U.S. National Transportation Safety Board has noted that DOT-111 tank cars have a high incidence of tank failures during accidents. Previous NTSB investigations that identified the poor performance of DOT-111 tank cars in collisions include a May 1991 safety study as well as NTSB investigations of a June 30, 1992, derailment in Superior, Wisconsin; a February 9, 2003, derailment in Tamaroa, Illinois; and an October 20, 2006, derailment of an ethanol unit train in New Brighton, Pennsylvania. In addition, on February 6, 2011, the Federal Railroad Administration (FRA) investigated the derailment of a unit train of DOT-111 tank cars loaded with ethanol in Arcadia, Ohio, which released about 786,000 US gallons (2,980,000 l; 654,000 imp gal) of product. The Transportation Safety Board of Canada also noted that this car's design was flawed resulting in a "high incidence of tank integrity failure" during accidents.
In Railway Investigation Report R94T0029, the Transportation Safety Board of Canada (TSBC) investigated a derailment incident near Westree, Ontario which occurred on 30 January 1994. They cited report NTSB/SS-91/01 which questioned "the safety of ... 111A tank cars." Furthermore, "... report [NTSB/SS-91/01] determined that this classification of tank car has a high incidence of tank integrity failure when involved in accidents and that certain hazardous materials are transported in these tank cars even though better protected cars (less liable to release the transported product when involved in accidents) are available." The TSBC instituted "Amendment Schedule No. 21 to the Transportation of Dangerous Goods Regulations", which mandated "the use of revised tank car standard CAN/CGSB 43.147-94. This standard restricts the use of 111A tank cars, and removes over 80 dangerous goods previously authorized for transportation in Class 111 cars." The status of Amendment Schedule No. 21 is unknown, as of August 2013, although the Standards Council of Canada reports that CAN/CGSB 43.147-94 was superseded by CAN/CGSB-43.147-97. The updated standard is available through the Canadian General Standards Board.
Approximately 230,000 litres (51,000 gallons) of sulphuric acid was released, causing environmental damage, on 21 January 1995 near Gouin, Quebec. "Unit trains of sulphuric acid were introduced into service in the 1950s. Sulphuric acid cars are usually loaded to the maximum allowable car weights. Loaded unit sulphur trains, with every car carrying maximum loading, present a severe concentration of mass over a relatively short length of track." The 11 rail cars that released product were standard series CTC-111A tank cars. The derailment was caused by gauge loss, and the number of defective ties north of the derailment area likely exceeded Canadian National's (CN) maintenance standard. Transport Canada determined that a retrofit of the top fittings of all Class 111A cars would exceed one billion dollars. The estimated cost of the Lac-Megantic derailment environmental cleanup (only) is one quarter of a billion dollars.
In Report Number R96M0011, the Transportation Safety Board of Canada (TSBC) investigated an occurrence near River Glade, New Brunswick which occurred on 11 March 1996. The 1996 report concluded that "Class 111A tank cars are more susceptible to release product upon derailment and impact than pressure tank cars, and yet there are a number of toxic and volatile liquids that are still permitted to be carried in minimum standard Class 111A tank cars." The report makes no recommendation to upgrade or limit the use of Class 111A tank cars.
On 2 May 2002, a train collided with a transport truck at the Firdale, Manitoba CN crossing. The derailed equipment included five tank cars carrying dangerous goods. During the derailment, four of the tank cars sustained multiple punctures and released their products. The products ignited and a large fire engulfed the derailed cars.
The National Research Council was commissioned via the Hazardous Materials Transportation Uniform Safety Act (1990) by the Federal Railroad Administration to write an impartial report on "(1) the railroad tank car design process, including specifications development, design approval, repair process approval, repair accountability, and the process by which designs and repairs are presented, weighed, and evaluated, and, (2) railroad tank car design criteria, including whether head shields should be installed on all tank cars that carry hazardous materials." It is entitled "Ensuring Railroad Tank Car Safety" and available as ISBN 0-309-05518-0.
Questions have been raised by the Transportation Safety Board of Canada investigators regarding the contents of the Lac-Mégantic train, because the "crude oil acted in ‘abnormal’ way". The Enbridge corporation "has complained numerous times to U.S. regulators that Bakken’s crude oil is volatile". This situation is similar to those that were detailed 12 years earlier in the Hazardous Materials Accident Report on the 'Rupture of a Railroad Tank Car Containing Hazardous Waste Near Clymers, Indiana'.
One issue raised by the Lac-Mégantic derailment, and substantiated by Enbridge complaints to the US regulator, is whether the DOT-111 tank car is the appropriate vessel to contain Bakken crude oil, given that the substance in question is associated with a notable volatility. A wider margin for safety would seem to be provided by the DOT 112 tank car. The explosive release of Bakken formation crude seen in the Lac-Mégantic derailment begs the question why this material is not classed as a HAZMAT Class 1 Explosives material.
The US Federal Railroad Administration moved on 8 August 2013 to tighten standards for shipments of crude oil from the Bakken formation (and other?) fields that contain volatile and/or corrosive chemicals, such as may issue from the hydraulic fracturing process. Crude oil is classed as HAZMAT Class 3 Flammable Liquids. The US regulator had ignored until 8 August 2013 the corrosive contents of Bakken formation crude oil. The immiscibility of crude oil and acid causes the acid to settle to the bottom of a container, and this may add to the corrosion. Given that a substantial fraction of rail stock is of DOT-111 type, the shipment of Bakken formation crude oil risks becoming more expensive over the medium term as the DOT-112 tank cars necessary for shipment will initially be relatively scarce.
Curiously, Federal Railroad Administration official Thomas J. Herrmann considers some crude oil not to be flammable. Hazardous materials standards, such as the HAZMAT Class 3 Flammable Liquids standard are notoriously difficult to read. Herrmann, who wrote a letter to the American Petroleum Institute on 29 July 2013, stated that "It is critical that shippers determine the proper classification of the crude oil". The Herrmann letter broadcasts the failure of the FRA to regulate adequately, with the result that "one shipper had put the highest degree of hazardous crude into a rail tanker suitable only for the lowest degree". Herrmann seems confused, because the American Petroleum Institute lobby may or may not communicate with, or represent, the shippers of crude oil. For example, in the case of the Lac-Mégantic derailment, the lessor of the DOT-111 tank cars World Fuel Services is a broker organization and in no way required to be members of the API lobby, so the effect of the letter to the API may be nil.
Hydrogen sulfide (H2S, sour gas), a gas which is toxic to humans and flammable, has been detected as well in Bakken crude by Enbridge. The academic community commented in 2011 that increased concentration of H2S was observed in the field and presented challenges such as "health and environmental risks, corrosion of wellbore, added expense with regard to materials handling and pipeline equipment, and additional refinement requirements". Holubnyak et al. write, further, that Bakken crude "may become soured through current oil field practices". At issue in the Lac-Mégantic derailment, then, is whether World Fuel Services and other defendants ought to have been aware of this two-year old research when they ordered the DOT-111 tank cars (which were already in 2012 acknowledged by the US NTSB regulator to be deficient for these purposes) to be loaded on the Lac-Mégantic train. The continued misuse as from 13 August 2013 of DOT-111 tank cars to ship Bakken formation petroleum may well liable for treble damages in US courts, because the behaviour is now known to be wanton.
The Lac-Mégantic runaway train had earlier passed through Toronto on its way from the Bakken[disambiguation needed] fields of Dakota. A Canadian National employee said that roughly 10% of shipments through Toronto contain hazardous materials that are often stored on DOT-111 tank cars, but that only first responders have access to HAZMAT shipment information.
As a result of an accident in Cherry Valley, Illinois, in 2009, the Association of American Railroads studied several options for increasing the crashworthiness of DOT-111 tank car designs and published new construction standards in a Casualty Prevention Circular, with the intent to revise the AAR Manual for Standards and Recommended Practices for tank cars that are used to transport ethanol and crude oil. Beginning on October 1, 2011, the new AAR standard for DOT-111 tank cars requires tank heads and shells to be constructed of thicker steel. The new specification also requires that heads and shells be constructed of normalized steel, and in all cases 1⁄2-inch (12.7 mm) thick half head shields must be provided. The AAR has also mandated a more robust housing or rollover skid for protection of top fittings. The new standards only apply to newly manufactured cars; there is no requirement to retrofit, repurpose, or retire existing DOT-111A cars built to the older design. The NTSB has called that design "inadequate," noting the older cars are "subject to damage and catastrophic loss of hazardous materials."
Had the tank cars in use for the Lac-Megantic derailment train been instead of DOT-112 tank car standard, they could have borne (a) a pool fire for 100 minutes; and (b) a torch fire for 30 minutes, and could have been able to withstand a coupler-to-head impact at up to 28.968 km/h. The consignor of the shipment involved in the Lac-Megantic derailment, World Fuel Services corporation, was responsible for leasing the DOT-111A tank cars.
This article incorporates public domain material from the National Transportation Safety Board document "Unclassified Safety Recommendation R-12-005-008, March 2, 2012".
This article incorporates public domain material from the National Transportation Safety Board document "DOT-111 Tank Car Design".
This article incorporates public domain material from the National Transportation Safety Board document "Derailment of CN Freight Train U70691-18 With Subsequent Hazardous Materials Release and Fire; Cherry Valley, Illinois; June 19, 2009".