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
10-0177 CSE Corporation Mr. Jeff Tocci View
PI-10-0001 B. Knight Natural Gas Services Mr. Michael H. Kyle View
10-0190 PCS Sales USA, Inc. Mr. Tracey G. Smith View
PI-10-0013 Pipestream, Inc Mr. Raymond N. Burke View
09-0306 Hazmat Resources, Inc. Mr. Danny Shelton View
10-0198 Smart-Hose Technologies Ms. Andrea Guevara View
10-0186 URS Corporation Ms. Erin N. Jarman View
10-0048 Department of National Defence Captain E.M. Steele View
10-0221 Metropolis Industries, LLC Mr. Kyle Long View
10-0126 Minnesota Department of Transportation Mr. Michael Ritchie View
10-0187 Schlumberger Technology Corporation Mr. Paul Lezak View
10-0204 Bureau of Explosives Transportation Technology Center, Inc. Mr. Sam Chapman View
10-0055 MidAmerican Energy Holdings Company Mr. Douglas E. Lunstra View
09-0093 Valspar Mr. Eric Barcaskey View
09-0158 LTL and Conslidation Consultant C.H. Robinson-Ann Arbor Branch Ms. Jennifer Kaczmarczyk View
10-0199 Britton & Associates, S.C. Mr. Larry J. Britton View
10-0197 Oxford & Wells Mr. Ken Swenke View
10-0184 Baker Petrolite Corporation Mr. Aubrey Campbell View
10-0091 Mr. Juan Gonzalez View
10-0127 AT&T Mr. Jim La Porte View
10-0109 Mr. Scott A. Pilch View
10-0042 Toyota Motor Sales, USA, Inc. Mr. Wieten View
10-0121 American Nuclear Portable Gauge Association Mr. George Marshall View
10-0173 Intertek Mr. Rich Byczek View
10-0164 Edgcomb Law Group Mr. John Edgcomb View
10-0202 Office of Packaging and Transportation, and Office of Environmental Management Mr. Stephen O"Connor View
CHI-10-005 Meeks, Sheppard, Leo & Pillsbury Andrea Abraham View
10-0192 Scopelitis, Garvin, Light, Hanson & Feary Mr. Timothy Wiseman View
10-0172 Forth Infrastructure & Environment, LLC Ms. Michele L. Frozena View
10-0051 Minnesota Department of Transportation Mr. Michael Ritchie View
10-0093R Edgcomb Law Group Mr. John Edgcomb View
09-0098 HazMat Resources, Inc. Mr. Danny Shelton View
PI-10-0003 Central Hudson Gas & Electric Corp. Mr. David W. Merte, P.E. View
PI-10-0004 South Carolina Office of Regulatory Staff Mr. Vernon Gainey View
10-0143 URS Corporation Mr. Andrew Romach View
10-0081 Gilmore Environmental Consulting, LLC Mr. John Thompson View
10-0176 The Chlorine Institute, Inc. Ms. Robyn Heald View
10-0167 Implant Technologies Mr. James V. McManus View
10-0160 Empire Airlines, Inc. Mr. Bradley J. Slater View
10-0166 Horizon Lines, LLC Mr. Cliff Bartley View
10-0106 Law Offices of Charles T. Simmons, LLC Mr. Charles T. Simmons View
10-0149 Minnesota Department of Transportation Mr. Mike Ritchie View
10-0150 Mid-South, Inc Mr. A B Eargood Brenntag View
10-0174 Integrity Inspection Services Mr. James Jagemann View
10-0137 National Oilwell Varco Mr. Jianke Wang, PH D, PE View
CHI-10-004 ACCU CHEM Conversion, Inc. Phil Zlaket View
10-0113 Currie Associates, Inc. Mr. S.C. Watkins View
10-0128 Aleris International, Inc Mr. Kenneth J. Willings View
PI-09-0020 Illinois Commerce Commission Mr. Darin R. Burk View
10-0140 Horizon Lines, LLC Mr. Cliff Bartley View