Transporting Crude by Rail Q&A

As the U.S. enters the domestic energy renaissance, the energy industry is using more crude from states such as North Dakota, Montana, and Texas, while importing less crude from overseas. Although this is a very positive development, our infrastructure is constantly changing to keep up with domestic demand. 

Approximately 10% of crude production is now shipped by rail. While transportation by rail is very safe – with more than 99.997% of all hazardous materials reaching their destination without incident – several incidents in recent years have drawn attention to the safety of rail transportation and the characteristics of shale plays in the Bakken. 

Rail safety is a shared responsibility and AFPM members are doing their part:

  • What requirements and regulations do refiners or shippers have to abide by when shipping crude via rail?
    • A refiner (or shipper) must comply with a variety of DOT HMR (Hazardous Materials Regulations) in order to ship crude by rail:
      • Determine the UN number and proper shipping name
      • Identify the proper hazard class and packing group (crude oil is classified as a Class 3 flammable liquid, and is separated into one of three possible packing groups: Packing Group I, II or III)
      • Prepare and retain shipping papers, which contain the packing group and hazard classification information.
      • Ensure that the tank car is authorized for transporting crude and determine the quantity of tank cars involved
      • Provide detailed emergency response information for first responders, including potential health hazards; risks of fire or explosion; intermediate methods to be taken for handling fires; initial methods for handling spills or leaks; preliminary first aid  measures; and a 24-hour emergency telephone number where more detailed information may be obtained
      • Offer a “shipper’s certification” affirming that the materials are properly classified, described, packaged, marked and labeled, and are in proper condition for transportation
  • What types of testing are required when shipping crude by rail?
    • Crude oil is a flammable liquid under DOT regulations.  As with all flammable liquids, to properly ship crude oil by rail it is necessary to assign the crude oil to the appropriate packing group, which measures how easily the liquid may ignite. The correct hazard level is determined by the flashpoint and boiling point of the crude oil. To ensure that the crude oil can be treated as a liquid and not as a gas, it is necessary to know the vapor pressure of the crude oil. The hydrogen sulfide content is also evaluated to determine whether the potential inhalation risk from hydrogen sulfide must be communicated while crude is in transportation.
    • The tests must account for the potential  variability of the crude oil being loaded, including the historical variability of crude oil properties, the stability of the crude oil, whether the crude oil is derived from single or multiple sources, and ambient temperature conditions. Testing must be conducted with sufficient frequency to ensure proper classification.  
  • Is Bakken crude properly classified as a flammable liquid?
    • Crude oil is currently shipped as a “Class 3 flammable liquid.” Based on AFPM’s third-party survey, Bakken crude is similar to other light crudes and transported in compliance as a Class 3 flammable liquid in Packing Group I or II (as required by the March 6, 2014 Emergency Order). Refined fuels are also transported via rail –  for example, gasoline, which may meet the criteria of packing groups I (high hazard) or II (medium hazard), is by regulation shipped as Packing Group II irrespective of whether it meets the criteria for Packing Group I or II.   Ethanol is commonly shipped as a Class 3, flammable liquid, Packing Group II.
  • What is packing group and how does it differ from classification?
    • Packing groups describe the degree of risk a hazardous material may pose in relation to other materials within the same hazard class to end use customers. There are three packing group
      • Packing Group I – High hazard level
      • Packing Group II – Moderate hazard level
      • Packing Group III – Low hazard level
  • How does classification impact what rail car is used to transport a certain material, like crude oil?
    • Proper classification is essential to determining which rail cars are authorized to transport certain materials. For example, AFPM’s third-party survey on Bakken crude characteristics found that Bakken crude oil is within the norm with respect to the hazard characteristics of other light crudes (i.e., flammable liquid).  While Bakken and other light crudes may contain higher amounts of dissolved flammable gases compared to heavy crudes, the percentage of dissolved gases would not cause Bakken crude to be transported under a different DOT hazard class other than hazard Class 3 and does not support the creation of a new DOT classification for rail transportation.
    • Furthermore, the maximum vapor pressure observed was 61% below the vapor pressure threshold limit for liquids under the HMR, demonstrating that Bakken crude is properly classified as a flammable liquid. Measured tank car pressures show that even the older DOT-approved 111 railcars authorized to transport Bakken crude are built within a wide margin of safety regarding the pressures that rail tanks may experience when transporting crude.
  • How does packing group impact what rail car is used to transport a certain material, like crude oil?
    • Packing Group is commonly used to tier the severity of HMR regulatory requirements. With regard to rail transportation, DOT 111 tank cars are authorized to transport all three packing groups.
  • What was the conclusion of AFPM’s rail survey?
    • In January, the Department of Transportation (DOT) asked AFPM for assistance in collecting information about the characteristics of Bakken crude – AFPM conducted a third-party survey of its members to address questions posed by DOT. A former DOT official then analyzed approximately 1,400 samples of Bakken crude, and concluded that Bakken crude is as safe to transport as other crudes and is well within the safety standards for current rail car designs.
    • Based on AFPM’s third-party survey, Bakken crude is similar to other light crudes and is transported in compliance as a Class 3 flammable liquid in Packing Group I, II or III. Furthermore, Bakken crude does not pose any significant risks or appreciable differences when compared to other crudes or flammable liquids that are authorized for rail transport.
    • Furthermore, Bakken crude meets the overall characteristics and definitions of a flammable liquid and is well within the regulatory limits for pressure, flashpoint, boiling point, and corrosivity characteristics.


  • Other than the properties of the material being shipped, why would the industry support more robust tank car standards?
    • Our industry is committed to a culture of safety and continuous improvement, with a goal of zero incidents. Within the past four years, AFPM members have voluntarily invested over $4 billion to upgrade tank cars. With the recent release of DOT’s final rule on enhanced tank car standards for high-hazard flammable trains, AFPM members are committed to working with DOT on implementation of the rule.
  • Other than tank car standards, what elements of rail safety should the federal government explore as it continues examining issues associated with the transportation of crude-by-rail?
    • Rail safety is a shared responsibility and our industry is working in partnership with regulators and other stakeholders. DOT recently finalized a rule addressing tank car standards; however, more attention must be paid to incident prevention and keeping the trains on the tracks—as track integrity and human error account for a large majority of rail incidents. As such, the debate should now focus on the remaining issues with rail transportation, including operability, track integrity and maintenance, and training for rail operators and emergency responders.