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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
Does a driver, employed full time by one motor carrier using the 60-hours in 7-days rule, and part-time by another motor carrier using the 70-hours in 8-days rule, have the option of using either rule in computing his hours of service? FMCSA-HOS-395.3-Q02 Hours of Service Maximum Driving Time
Are unladen converter dollies covered by the exemption in § 393.42(b)(2)? FMCSA-VEH-393.42-Q02 Are unladen converter dollies covered by brake exception for driveaway-towaway operations?
§ 393.42(b)(3) of the FMCSRs states that any full trailer, any semitrailer, or any pole trailer having a gross weight of 3,000 pounds or less must be equipped with brakes FMCSA-VEH-393.42-Q03 Must manufacturer install brakes on certain lightweight trailers?
Are tractor protection valves required by § 393.43(b), or may similar devices be used? FMCSA-VEH-393.43-Q01 Are tractor protection valves required?
Does the term ‘‘rear wheels’’ include the tag axle on a bus/motorcoach? FMCSA-VEH-393.44-Q01 Does “rear wheels” include bus tag axles?
If a CMV manufactured on or after July 25, 1980 (see § 393.42) has brake components on the front axle, and the brakes are not operable, does the vehicle comply with § 393.48? FMCSA-VEH-393.48-Q01 Is a post-1980 CMV with inoperable front brakes in compliance?
If a truck or truck tractor manufactured prior to July 25, 1980, and having 3 or more axles, has inoperable brakes on the front axle or some of the brake components are missing, would the vehicle be in violation of § 393.48? FMCSA-VEH-393.48-Q02 Is a pre-1980 CMV with inoperable front brakes in violation?
Are the brakes on a vehicle towed in a driveaway-towaway operation or towed disabled vehicle required to be operable at all times? FMCSA-VEH-393.48-Q03 Are operable brakes required on disabled or driveaway-towaway vehicles?
Is the low pressure warning device required to activate before the tractor protection valve? FMCSA-VEH-393.51-Q01 Must the low-pressure warning device activate before the tractor protection valve?
Is the vacuum portion of vacuum-assisted hydraulic brake systems required to have a warning device? FMCSA-VEH-393.51-Q02 Does vacuum assist on hydraulic brakes need a warning device?