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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

49 CFR Parts 100-199

PHMSA has published several Frequently Asked Questions (FAQs) documents on programmatic topics. Please review these documents here at:

Additionally, OHMS has published Hazardous Materials FAQs based on letters of interpretation on the following topics:

OHMS: 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).

OPS: 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: 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

Search the eCFR

Ref ID: Date Company Name Individual Name Response Document
00-0364 Barlen and Associates, Inc. Mr. William Barlen View
00-0366 Department of the Army Mr. Steven G. LaPoint View
00-0368 American Dental Supply, Inc. Mr. Les Hochhauser View
00-0378 TruGreen - ChemLawn Technical Center Mr. Roger A. Yeary View
00-0379 United States Senate The Honorable John Breaux View
00-0380 Bioject, Inc. Mr. Tom Brooks View
00-0381 Trailer Director Quality Distribution Mr. Charles Boudin View
00-0382 Federal Motor Carrier Safety Administration Stephen E. Barber View
00-0386 Safety & Compliance Associates, Inc Mr. Mike Lopez View
01-0001 Kessler Chemical Mr. Gary J. Kessler View
01-0002 Bernzomatic Mr. Roger L. Maxon View
01-0003 Nalco Chemical Company Mr. Everett Gauthier View
01-0010 Mr. Joseph Cormier View
01-0012 Reichhold Mr. Mark U. DuBois View
01-0013 Logistics Services Two Limited Mr. Michael F. Ryan View
01-0018 Overnite Transportation Company Mr. Garry Howell View
01-0021 Airpack of Virginia, Inc. Mr. Hank Baird View
01-0024 Grayson Hill Farm Mr. William Horn View
01-0025 Grayson Hill Farm Mr. Chris Schimp View
01-0027 Harmon Tank Company, Inc. Mr. Loy McGee View
01-0029 Georgia Public Service Commission Capt. Bruce Bugg View
01-0035 Polar Air Cargo Mr. Paul J. Zinza View
01-0036 New York State Department of Environmental Conservation Mr. Thomas Corbett View
01-0037 VP Buildings, Inc. Mr. Randy Geesing View
01-0038 William Wilkening View
01-0040 HMT Associates, L.L.C. Mr. E.A. Altemos View
01-0042 HB Fuller Company Mr. Gene Secor View
01-0046 Shell Chemicals Mr. David Mashinski View
01-0047 Aaron Oil Co., Inc. Ms. Lynn Clemmons View
01-0048 BOC Gases Mr. John M. Thompson View
01-0049 Naval Magazine Ms. Debra Olson View
01-0050 Mr. Tim Shaw View
01-0051 Zhen Hua Trading Limited Mr. Charles Ho View
01-0052 B Way Corporation Mr. Erik Martinsen View
01-0054R Georgia Department of Public Safety Captain Bruce Bugg View
01-0058 Monitor-Merrimac Memorial Bridge Tunnel Mr. Otis T. Eanes View
01-0059 Rapid Aid Ms. Judy Burtch View
01-0061 Glencore Mr. Michael O'Connell View
01-0062 General Dynamics Mr. Bruce F. Porter View
01-0064 Defense Logistics Agency Mr. F. Kevin Reilly View
01-0066 Degesch America, Inc. Mr. Michael E. Paynter View
01-0068 LR International Cosmetic & Marketing GmbH & Co. Mr. Michael Miska View
01-0069 Eastman Kodak Company Mr. Carl Spurchise View
01-0072 Container Service Co. Mr. Stephen C. Fulton View
01-0073 Matheson Tri-Gas Mr. Bobby Downer View
01-0075 Norcold Ms. Carol Bonner View
01-0082R MN DOT Office of Motor Carriers Mr. Michael Ritchie View
01-0084 Crompton Corporation Mr. Donald Hodder View
01-0085 West Marine Products Mr. Todd Nash View
01-0086 HMT Associates, L.L.C. Mr. E. A. Altemos View

E.g., 02/09/2021
E.g., 02/09/2021
Part/Section Subject
173.31 Use of tank cars
173.310 Exceptions for radiation detectors
173.312 Requirements for shipment of MEGCs
173.314 Compressed gases in tank cars and multi-unit tank cars
173.315 Compressed gases in cargo tanks and portable tanks
173.316 Cryogenic liquids in cylinders
173.319 Cryogenic liquids in tank cars
173.32 Requirements for the use of portable tanks
173.320 Cryogenic liquids; exceptions
173.322 Ethyl chloride
173.33 Hazardous materials in cargo tank motor vehicles
173.334 Organic phosphates mixed with compressed gas
173.336 Nitrogen dioxide, liquefied, or dinitrogen tetroxide, liquefied
173.35 Hazardous materials in IBCs
173.36 Hazardous materials in Large Packagings
173.4 Small quantities for highway and rail
173.40 General packaging requirements for toxic materials packaged in cylinders
173.401 Scope
173.403 Definitions
173.41 Sampling and testing program for unrefined petroleum-based products
173.410 General design requirements
173.411 Industrial packages
173.412 Additional design requirements for Type A packages
173.415 Authorized Type A packages
173.416 Authorized Type B packages
173.417 Authorized fissile materials packages
173.418 Authorized packages-pyrophoric Class 7 (radioactive) materials
173.419 Authorized packages-oxidizing Class 7 (radioactive) materials
173.421 Excepted packages for limited quantities of Class 7 (radioactive) materials
173.422 Additional requirements for excepted packages containing Class 7 (radioactive) materials
173.423 Requirements for multiple hazard limited quantity Class 7 (radioactive) materials
173.424 Excepted packages for radioactive instruments and articles
173.425 Table of activity limits-excepted quantities and articles
173.426 Excepted packages for articles containing natural uranium or thorium
173.427 Transport requirements for low specific activity (LSA) Class 7 (radioactive) material and surface contaminated objects (SCO)
173.428 Empty Class 7 (radioactive) materials packaging
173.433 Requirements for determining basic radionuclide values, and for the listing of radionuclides on shipping papers and labels
173.435 Table of A1 and A2 values for radionuclides
173.436 Exempt material activity concentrations and exempt consignment activity limits for radionuclides
173.441 Radiation level limitations and exclusive use provisions
173.443 Contamination control
173.447 Storage incident to transportation-general requirements
173.448 General transportation requirements
173.453 Fissile materials-exceptions
173.457 Transportation of fissile material packages-specific requirements
173.459 Mixing of fissile material packages with non-fissile or fissile-excepted material packages
173.461 Demonstration of compliance with tests
173.465 Type A packaging tests
173.467 Tests for demonstrating the ability of Type B and fissile materials packagings to withstand accident conditions in transportation
173.469 Tests for special form Class 7 (radioactive) materials