A transit bus's rear-door interlock holds its brakes while the door is open. May the driver rely on it instead of the parking brake?
Correct answer: No; use the proper parking brake rather than the door interlock.
A brake-door interlock may release as the door closes. Its door-safety function is not a substitute for properly parking the vehicle.
Source: Missouri Commercial Driver License Manual, revised August 2025; Section 4 (July 2017), 4.6 Use of Brake-door Interlocks; physical PDF page 68 (printed 4-4); reviewed September 15, 2026. ↗
A bus is being fueled and there is no need to run its engine for the fueling operation. What should the driver do?
Correct answer: Shut off the engine before fueling.
The federal rule prohibits fueling a CMV with its engine running except when engine operation is necessary to fuel it. Passenger comfort is not that exception.
Source: 49 CFR 392.50(a); eCFR displayed current through September 11, 2026; reviewed September 15, 2026. ↗
During bus fueling, how must the fuel-hose nozzle relate to the fuel tank's intake pipe?
Correct answer: Remain continuously in contact with the intake pipe.
The nozzle must remain in contact with the intake pipe while fueling. Also prevent smoking, flames and other foreseeable ignition hazards.
Source: 49 CFR 392.50(b)–(d); eCFR displayed current through September 11, 2026; reviewed September 15, 2026. ↗
A bus is disabled where having passengers get off would be unsafe. Under the handbook's guidance, how far may a necessary tow or push with them aboard go?
Correct answer: To the nearest safe place where the passengers can get off.
The handbook's exception is tied to unsafe unloading at the breakdown location. It calls for the nearest safe discharge point, not carrying passengers on a routine tow to a distant destination.
Source: Missouri Commercial Driver License Manual, revised August 2025; Section 4 (July 2017), 4.5 Prohibited Practices; physical PDF page 67 (printed 4-3); reviewed September 15, 2026. ↗
A driver proposes refueling a bus inside a closed building while its passengers remain aboard. What does the Missouri CDL handbook direct?
Correct answer: Do not refuel there with passengers aboard.
The handbook specifically warns against refueling in a closed building with riders aboard. Its general advice is to avoid fueling with riders aboard unless absolutely necessary.
Source: Missouri Commercial Driver License Manual, revised August 2025; Section 4 (July 2017), 4.5 Prohibited Practices; physical PDF page 67 (printed 4-3); reviewed September 15, 2026. ↗
Which stated exception to the federal ban on Class 1 explosives in the passenger space of a for-hire vehicle does the rule identify?
Correct answer: Small-arms ammunition, subject to the other applicable requirements.
The passenger-space rule identifies small-arms ammunition as an exception, not general permission for other explosives. Other shipment conditions still apply; this is not an ORM-D authorization.
Source: 49 CFR 177.870(c); Official eCFR XML dated September 11, 2026 was checked against the linked rule; reviewed September 15, 2026. ↗
Assume a for-hire passenger vehicle may lawfully carry a non-Class 1 hazardous shipment and no special exception applies. Under the federal per-class limit, what gross weight must one given class not exceed?
Correct answer: 45 kg (99 lb).
The rule uses 45 kg (99 pounds) per given class. Meeting this number alone does not authorize carriage; material, packaging, location and other conditions must also be met.
Source: 49 CFR 177.870(e); Official eCFR XML dated September 11, 2026 was checked against the linked rule; reviewed September 15, 2026. ↗
Assume authorized non-Class 1 hazardous articles on a for-hire passenger vehicle, with no special exception. What is their aggregate gross-weight limit under the federal rule?
Correct answer: 225 kg (496 lb).
The aggregate limit is 225 kg (496 pounds), in addition to the per-class limit and other requirements. The handbook's rounded 500-pound wording is not the precise current regulatory value.
Source: 49 CFR 177.870(e); Official eCFR XML dated September 11, 2026 was checked against the linked rule; reviewed September 15, 2026. ↗
A labeled Class 7 package qualifies for transport on a passenger-for-hire vehicle because no other practicable transport is available and all other conditions are met. Where may it be stowed?
Correct answer: In the trunk or baggage compartment, not an occupied compartment.
The rule restricts such packages to the trunk or baggage compartment and forbids storage in a compartment occupied by persons. Qualification for transport does not remove the location restriction.
Source: 49 CFR 177.870(g); Official eCFR XML dated September 11, 2026 was checked against the linked rule; reviewed September 15, 2026. ↗
A rider tries to board with a can of gasoline that has no hazard label. What should the bus driver do?
Correct answer: Prevent it from being brought aboard as ordinary carry-on baggage.
A missing label does not remove the hazard. The handbook specifically warns about passengers bringing common hazards such as gasoline or car batteries aboard.
Source: Missouri Commercial Driver License Manual, revised August 2025; Section 4 (July 2017), 4.2.1–4.2.2 Hazardous Materials; physical PDF page 66 (printed 4-2); reviewed September 15, 2026. ↗
