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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
05-0203 U.S. Coast Guard Mr. P.A. Cooley, MSTC View
05-0227 Regulatory Resources, Inc. Mr. Wade A. Winters View
05-0212 Truck Trailer Manufacturers Association Mr. Jeff Sims View
05-0213 Parts Plus Distribution Center Mr. Walter Kunz View
05-0219 Moulden Supply Company Mr. Robert R. Titcomb View
05-0236 Fisher Scientific International Mr. John 0. Mayfield, DGSA View
05-0252 Uwchalan Township Police Department CPL F. Allen Mauger, Jr. View
05-0190 EHS Associates, Inc. Mr. Daniel J. Young View
05-0224 CMP Industries LLC Mr. William Regan View
05-0242 Mr. Thomas L. Kettler View
05-0179 Taylor-Wharton Mr. Les Musselman, P.E. View
05-0194 Mr. Allan McCallum View
05-0131 Holman Fenwick & William Mr. Rory Butler View
05-0164 The Procter & Gamble Company Mr. Steven L. Dishion View
04-0261 Dangerous Goods Advisory Mr. Alan I. Roberts View
06-0124 Dangerous Goods Advisory Council Mr. Frits Wybenga View
05-0166 Boasso America Corporation Mr. Tony Ortego View
04-0274 Hitachi Transport System (America) Ltd Ms. Gina Lupian View
05-0187 Steptoe & Johnson, LLP David H. Coburn, Esq View
05-0173 Wrangler Corporation Mr. Russell Keith View
05-0186 Minnesota Department of Transportation Mr. Michael Ritchi View
05-0172 McCarthy, Sweeney & Harkaway, P.C Mr. Lawrence W. Bierlein View
05-0183 ShipMate, Inc. Mr. Steven Charles View
01-0012 Reichhold Mr. Mark U. DuBois View
05-0113 Michelman, Inc Ms. Tiffany Lawson View
05-0043 Allied Universal Corporation Ms. Robin J. Eddy Bolte View
05-0175 Kaivac, Inc. Mr. Bob Robinson, Sr. View
05-0026 AeroPro, Inc. Ms. Susan Foumier  View
05-0174 National Electrical Manufacturers Association, (NEMA) Mr. Mark Kohorst View
05-0161 Horizon Lines, LLC Mr. Cliff Bartley View
05-0076 Wiley Rein & Fielding LLP Mr. George A. Kerchner View
05-0156 CheckPoint Mailers Incorporated Ms. Sherry Anderson View
05-0139 The Field Museum Ms. Jolynn Willink  View
05-0138 MHF Logistical Solutions Mr. Kurt Colborn View
04-0058 Sherwin Williams Environmental, Health, & Regulatory Services Ms. Sandra Basham View
05-0148 PGM Global Logistices Ms. Debbie Hape View
05-0129 Pace International Union Mr. Randy Johnson View
05-0066 Scana Power for Living Mike E. Moore, P.G. View
05-0165 The Fertilizer Institute Ms. Pam Guffain View
05-0122 Heil Trailer International Mr. Joe Calonge View
05-0130 ABC Coke Mr. William R. Mason View
05-0081 Chemical Accident Reconstruction Service, Inc. Mr. Michael Fox View
05-0170 Mr. J.H. Cleveland View
05-0114 HazMat Environmental Group, Inc. Ms. Colleen A. Orth View
05-0115 United States Enrichment Corporation Mr. Don McCarty View
05-0136 Onyx Environmental Services, L.L.C. Ms. Jennifer Eberle View
05-0158 Georgia Gulf Sulfur Mr. Jerry J. Jennett View
05-0160 CheckPoint Mailers Incorporated Mr. Cliff Bartley View
05-0025 C.L. Smith Company Mr. Lonnie Jaycox View
PI-05-0101 Nieder, Bodeux, Carmichael, Huff, Lenox and Pashos, L.L.P Mr. Charles W. Nieder View