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Regulatory Guidance

Welcome to the FMCSA Guidance Portal. This web portal is a searchable, indexed database that contains and links to all guidance documents in effect from the Federal Motor Carrier Safety Administration. The guidance documents lack the force and effect of law, unless expressly authorized by statute or incorporated into a contract.

To comment on any guidance document, or to request issuance, reconsideration, modification, or rescission of any guidance document, please identify the guidance document in your request and send it to: FMCSAguidance@dot.gov. NOTE: The FMCSAguidance mailbox is not intended to serve as a mailbox for general inquiries. For inquiries that go beyond the limited purpose of the FMCSAguidance mailbox, please call FMCSA's Information Line (800-832-5660) or visit FMCSA's "Contact Us" page to send your inquiry to the appropriate mailbox.

Subject Agency Identifier Topic Issued Date
If a crack extended into the thickness of the glass at such an angle FMCSA-VEH-393.60-Q03 Definition of ¼” windshield crack
May a bus being operated by a for-hire motor carrier of passengers, under contract with a governmental agency to provide transportation of prisoners in interstate commerce, be allowed to operate with security bars covering the emergency push-out windows a FMCSA-VEH-393.62-Q01 May buses for prisoners block the emergency push-out windows?
When calculating the minimum emergency exit space required on school buses used in non-school bus operations, should two or three passengers per bench seat be used in determining the adult seating capacity? FMCSA-VEH-393.62-Q02 Seating capacity of school buses used for adults
Do school buses which meet the school bus emergency exit requirements established by NHTSA’s November 2, 1992, final rule on FMVSS No. 217 have to be retrofitted with additional emergency exits when used in interstate commerce for non-school bus operation FMCSA-VEH-393.62-Q03 Must school bus emergency exits be retrofitted for non-school operations?
Which edition of FMVSS No. 217 is required to be used in determining the emergency exit space requirements when retrofitting buses? FMCSA-VEH-393.62-Q04 Emergency exits for buses
May a fuel fill pipe opening be placed above the passenger floor level if it is not physically within the passenger compartment? FMCSA-VEH--393.65Q01 Placement of fuel pipe opening relative to passenger compartment
Must a motor vehicle that meets the definition of a "commercial motor vehicle" in § 390.5 because it transports hazardous materials in a quantity requiring placarding under the Hazardous Materials Regulations (49 CFR parts 171-180) comply with the fuel FMCSA-VEH-393.65-Q02 Must a vehicle with a GVWR under 10,001 pounds hauling hazmat comply with Subpart E of Part 393?
May a properly vented fuel cap be used on a fuel tank equipped with another fuel venting system? FMCSA-VEH-393.67-Q01 Topic: Use of vented fuel cap in addition to other fuel system
Do the FMCSRs specify a particular pressure relief system? FMCSA-VEH-393.67-Q02 Pressure relief systems
What standards under the FMCSRs must be met when a liquid fuel tank is repaired or replaced? FMCSA-VEH-393.67-Q03 Repairing/replacing liquid fuel tanks