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
15-0229R Idaho State Police Mr. Thomas Wright View
16-0128 Cimarron Oil LLC Mr. Anthony Rausin View
16-0079 Patterson Companies, Inc. Mr. Robb Boros View
16-0099 Veolia North America Jennifer Eberle View
PI-16-0009 Mr. Jonathan C. Wolfgram Minnesota Department of Public Safety View
16-0089 Label Solutions, Inc. Ms. Tammy King View
16-0109 Spectrum Techniques Mr. Daniel Sims View
15-0044 Northern Air Cargo Mr. Mark Smith View
16-0158 PRI International, Inc. Mr. Vincent Vitollo View
16-0083 NGL Crude Logistics, LLC. Mr. Don Robinson View
16-0055 AZKO Nobel Services, Inc. Mr. Mark Connolly View
16-0023 Williams International Mr. Stan Harrison View
16-0136 DuPont Corporation Center for Safety, Health, and Environment (SHE) Mr. Kevin Greene View
PI-15-0014 Petersen Engineering Mr. J. Douglas Lindsay View
16-0024 Williams International Mr. Stan Harrison View
16-0131 Alabama Power Ms. Sharon Trippany View
PI-16-0008 Maverick International, LTD Mr. Jerry Nelson View
16-0129 National Cargo Bureau Mr. Edward Walker View
16-0069 Brenntag North America, Inc. Mr. Bruce Biehl View
16-0100 Potash Corp. Mr. Tracey Smith View
16-0088 Landstar Transportation Logistics, Inc. Mr. Wes Pace View
16-0072 CETECOM Japan K.K. Mr. Karsten Koller View
16-0094 Edmundo B. Fernandez, Inc. Ms. Monica Fernandez View
PI-16-0005 King-Murray Company Operating LLC Mr. Frank M. Murray View
16-0078 Environmental Resources Center Ms. Lizzie Clifton View
16-0044 Hall, Render, Killiam, Heath & Lyman, PC Ms. Amy Berenbaum Goodman View
16-0081 N&M Transfer Co.,Inc. Mr. Cary Krickeberg View
16-0039 GEO Dynamics Inc. Mr. Brett Lehman View
16-0114 Renaldo Sales & Service, Inc. Mr. Kerry Fitzgerald View
16-0101 Belshire Environmental Services, Inc. Mr. Larry Moothart View
16-0104 Ms. Amanda Hammon View
16-0059 Ningbo Zhengxin Fire Fighting Equipment Co., Ltd Mr. Jacky Xie View
16-0027 Graham Packaging Company, L.P. Mr. Matthew Parker View
16-0061 XPO Logistics Mr. Jeff Messe View
16-0031 Container Technologies Industries, LLC. Mr. Steve Fielden View
15-0227R Artisan EHS Consulting, LLC. Mr. David Comen View
15-0171 AECOM Mr. Andrew Romach View
16-0115 The Dow Chemical Company Mr. John Heater View
15-0233 Inmark Packaging Mr. Jay Johnson View
16-0060 Ms. Tory Foster View
16-0053 ASCM- FedEx Freight Mr. Frank Horvat View
16-0049 Slade's Industrial Services, Inc. Mr. James Theriot View
16-0048 Public Utilities Commission of Ohio Mr. Ronald Swegheimer View
16-0063 The Dow Chemical Company Mr. John Jeater View
16-0085 Office of Motor Vehicle Enforcemen Captain Dean House View
16-0080 Technology Solutions Mr. William Weddle View
16-0067 Mr. Francis J. Mendez View
16-0021 Entergris, Inc. Mr. David Weisbrich View
16-0035 SJ Transportation Co. Inc. Ms. Maureen Poole View
16-0045 Label master Services, Inc. Mr. Robert Richard View