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Below are the available interpretations and guidance for the given section. To return to the list of parts, use the Parts link above. If you do not see any guidance or interpretation information below, that means there is none available for the given part/section. Return to the search page to browse additional regulations sections.

PHMSA has published several Frequently Asked Questions (FAQ) documents on regulatory topics. Please review our FAQ documents below:

Additionally PHMSA has Hazardous Materials FAQs based on letters of interpretation on the following topics:

This section of the website provides the ability to find regulations information including regulations parts, content of sections, and interpretations for regulations sections. Below is a list of parts, identified by the part number and subject. 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.

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.

The regulations text of the section can be found on the eCFR website. To view the regulations text, use the link below. For assistance, please send an email to

View part 177 on the ECFR website

Regulation Sections

Section Subject
177.800 Purpose and scope of this part and responsibility for compliance and training
177.801 Unacceptable hazardous materials shipments
177.802 Inspection
177.804 Compliance with Federal Motor Carrier Safety Regulations
177.810 Vehicular tunnels
177.816 Driver training
177.817 Shipping papers
177.823 Movement of motor vehicles in emergency situations
177.834 General requirements
177.835 Class 1 materials
177.837 Class 3 materials
177.838 Class 4 (flammable solid) materials, Class 5 (oxidizing) materials, and Division 4.2 (self-heating and pyrophoric liquid) materials
177.839 Class 8 (corrosive) materials
177.840 Class 2 (gases) materials
177.841 Division 6.1 and Division 2.3 materials
177.842 Class 7 (radioactive) material
177.843 Contamination of vehicles
177.848 Segregation of hazardous materials
177.854 Disabled vehicles and broken or leaking packages; repairs
177.87 Regulations for passenger carrying vehicles