Nearly half—48%—of rail tank cars carrying Class 3 flammable liquids in 2019 in the US met the new safety requirements, up from 33% in 2018, according to Fleet Composition of Rail Tank Cars Carrying Flammable Liquids: 2020 Report released today by the US Department of Transportation’s Bureau of Transportation Statistics. Class 3 flammable liquids most commonly include crude oil, ethanol, and refined petroleum products.

A series of several high-profile derailments and explosions prompted the US and Canadian governments to reexamine the safety standards that govern the transport of class 3 flammable liquids. DOT’s Pipeline and Hazardous Materials Safety Administration (PHMSA) and Federal Railroad Administration (FRA) issued a final rule on 8 May 2015, intending to make transporting flammable liquids safer. This rule, Hazardous Materials: Enhanced Tank Car Standards and Operational Controls for High-Hazard Flammable Trains (HM- 251), included regulations to upgrade those cars operating in high-hazard flammable trains (HHFT).

The new report tracks the transformation of the fleet carrying class 3 flammable liquids to be a fleet of DOT-117s, which meet new safety requirements.

Characteristics of the new DOT-117s include a thicker tank wall with insulation, puncture protection, a full head shield, and top and bottom valve fitting protections. The head shield is on both ends of the tank car and is a thicker wall to resist puncture in a derailment. The top and bottom valves are for filling and emptying the tank car and need to be protected against shearing off in a derailment and allowing a release of a flammable liquid.

Currently some class 3 flammable liquids are carried in rail tank cars, such as DOT-111s, which have fewer safety features. It is expected that the transformation of the fleet will be complete by 2029.

For crude oil alone, 73% of the tank car fleet in 2019 consisted of DOT-117s, up from 46% in 2018. Non-jacketed DOT-111s, which do not meet the new safety standards, have not carried crude oil since 2016 and the percentage of all other tank car types carrying crude oil dropped from 66% in 2017 to 28% in 2019.

DOT-111s were required to stop carrying crude oil in 2018. Non-jacketed tank cars lack a layer of insulation and/or thermal protection between the tank shell and jacket that stabilizes the temperature of the liquid contained in the tank car and reduces the conductivity of heat from outside sources to the contents of the tank car. Non-jacketed DOT-111s are in the process of being phased out of the fleet of tank cars carrying Class 3 flammable liquids, and will be completely phased out by 2029.

The report describes the progress of tank car safety upgrades from 2013 through 2019, by tank car type and type of flammable liquid.

In 2019, 112,685 rail tank cars were used to carry Class 3 flammable liquids, which is nearly as many as the 2015 fleet of 113,045 rail tank cars. In 2015, only 3% of the fleet carrying crude oil and other Class 3 flammable liquids consisted of the DOT-117s which meet the new safety standards, compared to 48% in 2019.

Survey results indicate that 7,938 DOT-117 and DOT-117R tank cars are projected to be built or retrofitted in 2020.

The annual BTS report is required under the 2015 FAST Act (Fixing America’s Surface Transportation Act), Section 7308. Additionally, Section 7308(c) requires BTS to estimate the antici­pated number of DOT-117 and DOT-117R tank cars for each year from 2018 through 2029 by collecting data from tank car shops that build or retrofit tank cars. It is expected that by the end of the transition period in 2029 all Class 3 flammable liquids will be carried in rail tank cars that meet or exceed the DOT-117 or DOT-117R specification.