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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. FMCSA may not cite, use, or rely on any guidance that is not posted on this Guidance Portal, except to establish historical facts.

This Guidance Portal represents the exclusive source of guidance that the FMCSA has determined is in effect. In accordance with Executive Order 13891 and OMB Memorandum M-20-02, any previously issued guidance that does not appear in the Guidance Portal is considered rescinded and of no legal effect.

For more information regarding the procedures associated with the development and issuance of DOT guidance documents, please see the Department’s regulations on “Administrative Rulemaking, Guidance, and Enforcement Procedures” (December 27, 2019). To comment on any guidance document, or to request issuance, reconsideration, modification, or rescission of any guidance document in accordance with 49 CFR 5.41, send your request to: FMCSAguidance@dot.gov. Please identify the guidance document in your request.

Subject Agency Identifier Topic Issued Date
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
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?
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 decal designed to comply with the periodic inspection documentation requirements of § 396.17 be displayed on the windshields or side windows of a CMV? FMCSA-VEH-393.60-Q02 May CVSA decals be displayed on windows?
May windshields and side windows be tinted? FMCSA-VEH-393.60-Q01 Tinting of windshields and side windows
May the information in the stopping distance table be used to determine the stopping distances at speeds greater than 20 mph? FMCSA-VEH-393.52-Q01 Can the stopping-distance table be used for speeds above 20 mph?
What difference, if any, is there between a warning device and a warning signal? FMCSA-VEH-393.51-Q05 What’s the difference between a warning device and a warning signal?
Is a warning device required in a Commercial Motor Vehicle (CMV) with a single hydraulic brake system which uses the driveline parking brake as the emergency brake system? FMCSA-VEH-393.51-Q04 Is a warning device required on a hydraulic brake system with driveline parking brake as emergency brake?
Are vacuum gauges required on the vacuum portion of vacuum-assisted hydraulic brakes? FMCSA-VEH-393.51-Q03 Do vacuum-assisted hydraulic brake need a gauge on the vacuum portion?
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?