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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Letters of Interpretation

PHMSA has published several Frequently Asked Questions (FAQs) documents on programmatic topics. Please review these documents here at: https://www.phmsa.dot.gov/about-phmsa/phmsa-faqs.

Additionally, Office of Hazardous Materials Safety has published Hazardous Materials FAQs based on letters of interpretation on the following topics:

Office of Hazardous Materials Safety: For questions about transporting hazardous materials, needing clarifications of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180), or requesting a formal letter of interpretation, please go to the Hazardous Materials Information Center (HMIC) page for contact information (phone and email address). Pending interpretation letters that are under review by the Office of Hazardous Materials Safety can be found at Pending Hazardous Materials (Hazmat) Interpretations.  

Office of Pipeline Safety: A written regulatory interpretation, response to a question, or an opinion concerning a pipeline safety issue may be obtained by submitting a written request to the Office of Pipeline Safety (PHP–30), PHMSA, U.S. Department of Transportation, 1200 New Jersey Avenue SE., Washington, DC 20590–0001 or at the email address: pipeline_interp_submittal@dot.gov. In addition to email address, the requestor must include his or her return address and should also include a daytime telephone number. Requests should be submitted at least 120 days before the time the requestor needs a response. Note: electronic submission is provided as alternative to the 49 CFR Part 190.11(b) mail-in requirement.

Interpretation letters under review are available at the Office of Pipeline Safety’s Interpretation Review page. To submit comments on an interpretation under review, proceed to the Interpretation Review page, locate the interpretation to comment on, and click the appropriate link to submit a comment on the corresponding interpretation. Comment submissions will be accepted for 30-days after the interpretation letter is posted.

This section of the website below provides the ability to find regulations information including regulations parts, content of sections, and interpretations for regulations sections. A list of parts, identified by the part number and subject is also provided. To browse sections by part, click on the subject link below. You will be taken to the eCFR website to view sections for a part.

The eCFR is also searchable by keyword and other available options on the eCFR website. To search and browse regulations using the eCFR website, use the link below. For assistance, please send an email to PHMSA.Webmaster@dot.gov.

Search the eCFR

Interpretations Reference #

Search Tip: Use quotation marks to search for commonly used phrases, such as “gas transmission” or “cargo tank motor vehicle.”
E.g., 02/09/2021
E.g., 02/09/2021
Ref ID: Date Company Name Individual Name Response Document
98-0428 HAZMAT and Dangerous Goods Program Charles Lovinski View
98-0163 Mr. Kent F. Blair View
98-0038 Digital Audio Disc Corporation Mr. Gary J. Garrahan View
PI-98-0101 U.S. Department of Transportation Richard Sanders View
98-0119 Department of California Highway Patrol Mr. R. B. Wood View
98-0135 Dreyco, Inc. Mr. Gareth D. Pearce View
98-0576 Hazmat Guru Consulting Mr. H.J. Pace View
98-0111 Department of Environmental Quality Mr. Daniel Schultz View
98-0133 Sumitomo Corporation of America Mr. Thomas M. Riederer View
98-0112 Radioactive Waste Acceptance Program Mr. Michael Noland View
98-0021 Wright Corporation Mr. Rick Wells View
98-0127 Hodgdon Powder Co., Inc. Mr. Ben Barrett, P. E. View
98-0575 DGI Training Center Ms. Candy L Cook View
98-0048 Lockheed Martin Government Mr. David A. Sutton View
98-0117 The Andersons, Inc. Mr. Jeff Anderson View
98-0044 Transportation Technology Center, Inc. Mr. W. J. Oertly View
98-0552 Olin Microelectronic Materials Ms. Naomi Livingston View
98-0057 American Trucking Associations Mr. Paul Bomgardner View
98-0420 Van Waters & Rogers Inc. Mr. Carl M. Larson View
98-0406 Westvaco — Corporate Center Mr. Fred V. Hayton View
98-0544 nternational Air Transportation Mr. Gary Dixon View
98-0049 Kaiser Permanente Medical Care Program Ms. Tammi Keating View
98-0045 Dangerous Goods of America, Inc. Mr. Fred Romero View
98-0051 HAZMAT and Dangerous Goods Program Charles Lovinski View
98-0594 Greif Bros. Corporation Mr. Joseph Grebe View
98-0020 Goshen Corporate Park West Mr. David B. Caria View
98-0580 The Chlorine Institute, Inc. Mr. John P. Aherne View
98-0581 The Chlorine Institute, Inc. Mr. John P. Aherne View
98-0596 Fort Edward Express Co., Inc. Mr. Douglas J. Varney View
98-0554 Department of Transportation R. I. Reinemann View
98-0411 Farmland Industries, Inc. Mr. Jack Curry View
98-0040 Finetex Inc. Mr. Bob Scala View
98-0429 Environmental Management and Controls, Inc. Mr. Dan A. Tallman View
98-0053 Oxbow Carbon & Minerals, Inc. Ms. Karen Ferragonio View
98-0507 Interwest Home Medical Mr. James VanSchoonhoven View
PI-98-004 UMAC, Inc. John B. McGowan, Jr. View
PI-98-005 Williams Field Services Chris Mason View
98-0419 Gallard-Schlesinger Industries, Inc. Ms. Virginia Slowik View
98-0417 Hunt ShipMate, Inc. Mr. Steven Charles View
98-0408 ALM Safety Associates Mr. Allen L. Mossman View
98-0563 STC Technologies, Inc. R. Sam Niedbala, Ph.D.,BCFE View
98-0409 Vessels Limited Mr. Martin Laverty View
98-0515 Autoliv ASP, Inc. Mr. Terry Zost View
98-0592 Mr. Roy E. Hanson View
98-0569 TANKCON Mr. Al Chatillon, P. Eng. View
98-0522 DuPont Sourcing Mr. Randolph Martin View
98-0574 ADea Services, Inc. Mr. Leonard J. Warbiany View
98-0014 DRMO-Luke Mr. Eddie Ellis View
98-0535 Hodgdon Powder Co., Inc. Mr. Ben Barrett, P. E. View
98-0595 Truck Trailer Manufacturers Association Mr. Donald W. Vierimaa View