USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

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
08-0266 International Biophysics Corporation (IBC) Mr. William R. Wilkinson View
08-0268 University of Chicago Ms. Susan Grover View
08-0277 Mr. Lawrence W. Bierlein View
08-0258 Republic Airways Holdings Mr. John E. Martiney View
08-0190 Cytec Industries, Inc. Mr. James Sompii View
08-0294 The Law Offices of Michael A. Capuzzi Mr. Michael A. Capuzzi, Esq. View
08-0097 C&R Fleet Services, Inc. Mr. Anthony Reid View
08-0151 Van Hool NV Mr. Chris Vleugels View
08-0185 EHS Associates, Inc. Mr. Daniel J. Young View
08-0275 Atlantic RO-RO Carriers, Inc. Mr. Andrei Lazourenko View
08-0284 Momentive Performance Materials Mr. Michael T. Shamulka  View
08-0252 Federal Reserve System Cash Product Office Federal Reserve Bank of San Francisco, Los Angeles Branch Mr. Alex Torres View
08-0209 Biodiversity Research Institute University of Kansas Mr. Andrew Bentley View
08-0233 Mr. Guttemberg Costa Botejo View
08-0243 Lovelace Gas Service, Inc. Mr. Bill Lovelace View
08-0285 North Carolina State Highway Patrol Trooper C. R. King View
08-0213 FedEx Express Mr. Scott A. Mugno View
08-0290 Sensitech, Inc. Mr. Henry Ames View
08-0206 Climate Controlled Containers, Inc. Mr. Ken Broussard View
08-0281 United Parcel Service Mr. Samuel S. Elkind View
08-0263 Foth Ms. Sheryl Pham View
08-0274 Alcor Life Extension Foundation Ms. Tanya Jones View
08-0276 PAML Ms. Marguerite Busch View
08-0267 National Electrical Manufacturers Association Mr. Kyle Pitsor View
08-0237 OxLife LLC Mr. Stuart H. Bassine View
08-0201 Triumvirate Environmental, Inc. Mr. John Menzigian View
08-0273 Mr. Andrew Abrams View
08-0259 Entergy Corporation Mr. Bob Hayden View
08-0229 DeVibiss Healthcare Mr. David Greene View
08-0245 Department of Energy Mr. James M. Shuler View
08-0253 Kajuligan Corporation Mr. Clifford E. Croft View
08-0240 Association of American Railroads Mr. Robert E. Fronczak View
08-0077 Earth Tech, Incorporated Mr. Bob Crump View
08-0197 Silver/Cims LLC Mr. Jim Silver View
08-0214 DuPont Global Logistics Mr. Kevin Greene View
08-0225 Currie Associates, Inc. Mr. Jack Currie View
08-0238 Emerson Process Management Mr. Scott A. Ferguson View
08-0119 Bluegrass Army Depot Ms. Gretchen Schmidt View
08-0270 URS Corporation Mr. Andrew Romach View
08-0232 Mr. Lawrence Bierlein View
08-0179 DeOrchis & Partners, LLP Mr. Richard L. Furman View
08-0250 Republic Airways Holdings Mr. John E. Martiney View
08-0236 Obadal, Filler, MacLeod & Klein, P.L.C. Mr. Colin P. Carroll View
08-0134 Hawkins, Inc. Mr. Chris W. Gibson View
08-0247 Henry Ford Hospital Ms. Carolie Horvath View
08-0234 NASA Wallops Flight Facility Mr. Ernest Conwell View
08-0123 Mr. Mark. M. Baron View
08-0218 First Alert BRK Brands, Inc. Mr. Brian J. Strasma View
08-0169 Berger Brothers, Inc. Mr. Kurt Knaack View
08-0226 DtLwKdo USA/CAN S4 Rüdiger Peil View