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).

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.

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
21-0050 Arcimoto, Inc. Pete Z View
PI-20-0001 Public Utilities Commission of Nevada Mr. Neil Pascual View
21-0036 Entergy Operations Inc. Donnie James View
21-0025 Schneider National Bulk Carriers Shannon Schick View
PI-19-0017 Flint Hills Resources Ms. Kim Gerold View
PI-21-0005 Wright and Associates PLLC Ms. Charlene B. Wright View
20-0087 DHL Global Forwarding Philip Poland View
21-0035 Momentive Performance Materials Kirsten Pink View
PI-21-0002 High Roller E&C, LLC Mr. Rob Harman View
20-0094 Stabilis Solutions Mr. Vignesh Pandurengan View
21-0019 Burlington Products, Inc. Bill Greene View
21-0010 Kansas Highway Patrol Nicholas Wright View
21-0012 RCS RMS Inc. Donna Adams View
21-0001 Oilmen’s Truck Tanks Robert Strong View
21-0024 Matson Navigation Company James Owen View
21-0028 McCallum Rock Drilling Darren Amman View
20-0084 LANXESS Corporation Cyndi Fink View
21-0003 N&M Transfer Co., Inc. Cary Krickeberg View
21-0029 TETRA Technologies Shawn Shoemake View
21-0009 BCA Packaging Services Nelson Kays View
21-0034 Keith Baecht View
20-0053 Hasa, Inc. Dave Johnson View
21-0016 Amanda Davis View
20-0081 Stablex US ecology Pierre-Olivier Gagné View
21-0005 Rescar Companies J. Andrew Schaffer View
20-0078 Starkey Laboratories, Inc. Dawn Gardner View
21-0015 Iowa Dept. of Transportation Robert Johnson View
21-0007 Truck Trailer Manufacturers Association John Freiler View
21-0011 Air-Conditioning, Heating, and Refrigeration Institute (AHRI) Helen Walter-Terrinoni View
20-0073 John B. Woodbury View
20-0068 Zoll Medical Corporation George Cole View
21-0021 XPO Logistics – Supply Chain Erin Sineath View
21-0004 P.O.R. Products Mark Newitz View
20-0030 ORBITAL ATK Robert Weston View
21-0006 Fletcher & Sippel LLC Michael Barron View
20-0088 National Presto Safety J.R. Nerat View
20-0040 Silverback Consulting Group LLC Michael Di Giorgio View
20-0062 Daniels Training Services, Inc. Daniel Stoehr View
20-0064 MRIGlobal-NCR Malcolm Smith View
20-0033 Fleener Consulting LLC Mr. Arthur L. Fleener View
20-0055 Port of Portland Geoff Owen View
20-0082 Lawrence Bierlein View
20-0092 Public Utilities Commission of Ohio Transportation Department Tom Forbes View
20-0083 Growmark, Inc. Tom Bryant View
20-0035 Centers for Disease Control and Prevention (CDC) Lori Bane View
20-0089 Austin Powder Company Darrell A. Martin View
20-0070 Jacam Chemicals 2013, LLC Jason Ontjes View
20-0091 Van Diest Supply Company Bret Hilpipre View
21-0002 Centers for Disease Control and Prevention (CDC) Dr. Jeanne Santoli, M.D. View
20-0077 Neoteryx Stuart Kushon View