U.S. Department 

of Transportation 

Federal Railroad 

Administration 

Mr. Patrick M. Brady 

Assistant Director, Hazardous Materials 

BNSF Railway 

4200 Deen Road 

Fort Worth, TX 76106 

Dear Mr. Brady: 

1200 New Jersey Avenue. SE 

Washington, DC 20590 

The Federal Railroad Administration (FRA) understands that BNSF Railway (BNSF) is 

planning to conduct testing to determine ifthe use ofNatural Gas, Refrigerated Liquid, 2.1, 

UN 1972 (LNG) is a viable fuel source for locomotives. In connection with this planned 

testing, BNSF has requested (1) an interpretation ofthe applicability ofthe Federal 

Hazardous Materials Regulations (HMR) (Title 49 Code ofRegulations (CFR) Parts 171-

180) to fuel tenders supplying diesel or LNG fuel to locomotives, and (2) FRA approval 

pursuant to 49 CFR Sections 174.63 to transport LNG in intermodal portable tanks in 

container-on-flatcar service. This letter responds to your request for an interpretation of the 

applicability ofthe HMR to fuel tenders supplying fuel to railroad locomotives. FRA will 

respond separately to your request for approval pursuant to 49 CFR § 174.63. Since the 

requested interpretation relates to the HMR, which are promulgated by the Pipeline and 

Hazardous Materials Safety Administration (PHMSA), FRA has coordinated its response 

with that agency. 

Although LNG is a regulated hazardous material under the Federal hazardous materials 

transportation law, that law applies to the transportation of hazardous materials in commerce. 

See 49 U.S.C. § 5103 and 49 CFR § 171.1(c). Consistent with the statute and the HMR, 

PHMSA has consistently found that a fuel tank used only for supplying fuel to operate a 

transport vehicle or its auxiliary equipment is not subject to the HMR (see 49 CFR § 171.8). 

Accordingly, both PHMSA and FRA have concluded that the testing currently planned by 

BNSF is not within the scope ofthe HMR. More generally, the use of a fuel tender 

supplying fuel (whether it be diesel or another regulated hazardous material) to locomotives 

is not within the scope of the HMR and is, therefore, not subject to those regulations. The 

agencies note, however, that if the tender equipment needs to move via rail while the 

equipment is not serving as a tender (i.e., not supplying fuel to an accompanying 

locomotive), the equipment would be considered "in transportation" and subject to the HMR. 

See 49 CFR § 171.8. 
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In accordance with FRA's overall rail safety authority, FRA has the authority to regulate 

vehicles that serve as locomotive tenders. As such, any vehicle that carries LNG or any other 

material being used to fuel attending locomotives is subject to FRA's statutory and 

regulatory authority. See 49 U.S.C. §§ 20701-20703 (formerly known as the Locomotive 

Inspection Act). The Locomotive Inspection Act, in part, prohibits a railroad from using a 

locomotive or tender unless the equipment is "in proper condition and safe to operate without 

unnecessary danger of personal injury." Accordingly, BNSF must ensure that both the 

locomotive and the equipment serving as locomotive tenders are safe to prior to initiating the 

test. See 49 CFR § 229.7. Therefore, the safety rationale supporting the regulatory 

requirements contained inFRA's rail safety regulations concerning locomotives, locomotive 

tenders, freight cars, and safety appliances (including, but not limited to, 49 CFR Parts 215, 

229, 230, and 231) must be considered in evaluating the safety of the equipment and its 

proposed operation, and in determining compliance with the statute. Although the HMR are 

not directly applicable to the proposed equipment and its operations, the safety rationale 

underlying those regulations (including, but not limited to, the operational and packaging 

standards of the HMR) must also be considered. There are specific statutory and regulatory 

requirements related to safety appliances on all vehicles, including locomotive tenders, which 

must be considered. See 49 U.S.C. §§ 20302 and 20303 and 49 CFR Part 231. 

FRA expects that prior to initiating any testing of the new dual-fuellocomotives and tender 

vehicles, BNSF will conduct, and provide to FRA for its approval, a comprehensive safety 

analysis identifying the risks of the operation and measures put in place to mitigate those 

risks. At a minimum, the analysis must address the following inherent risks: 

• The design of the natural gas tender, including the crashworthiness of the packaging, 

as well as all connections to the locomotives being fueled. 

• The placement and operation of a tender containing LNG and operating as a potential 

ignition source adjacent to an occupied locomotive. 

• The ability of first responders to identify the contents of the tender vehicle in the 

event of an accident. 

• The heat leak rate into the LNG storage tank (including the effect of sloshing) and the 

consequent pressure buildup inside the tank. 

• The release of flammable vapors into the atmosphere to relieve tank pressure. 

• Mechanical issues related to the equipment. 

FRA and PHMSA would like to partner with BNSF to ensure that the testing of the proposed 

new dual-fuel locomotives and their accompanying tenders is carried out safely and in 

accordance with existing statutory and regulatory requirements. The conditions applicable to 

any testing initially approved by FRA will be subject to change based on the results of the 

testing or information gathered from the testing. Further, the use of the proposed new 

equipment in regular revenue service may be subject to future regulatory action. 

FRA applauds BNSF's efforts to identify viable alternative fuel sources for locomotives and 

address the issue oflocomotive emissions through the use of new and innovative technology. 
FRA also appreciates the continued opportunity to participate in the LNG Locomotive 

Technical Advisory Group as part of the Association of American Railroads' Locomotive 

Committee. We look forward to working closely with BNSF to determine the feasibility of 

advancing this technology. 

Sincerely, 

vm::ft88t"':r:. o gue 

Acting Associate Administrator for Railroad Safety/Chief Safety Officer 

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