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A
Amber lights are used only in bad weather
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B
Amber lights warn approaching traffic that the bus is preparing to stop and load/unload students — activate 200 feet (in city) to 400-500 feet (on highway) before the stop to give drivers time to slow and prepare to stop for the red lights
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C
Amber lights indicate the bus needs to be passed on the left
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D
Amber lights replace the need for a stop sign arm
Why this is the answer
THE AMBER FLASHING LIGHT SEQUENCE is a critical warning system that gives approaching traffic advance notice before the bus activates its mandatory red stop lights. TIMING REQUIREMENTS: Most states specify activation distances: URBAN/SUBURBAN areas (under 35 mph): activate approximately 100-200 feet before the stop; RURAL/HIGHWAY areas (35+ mph): activate 200-500 feet before the stop; the greater the vehicle speeds, the more advance warning required for drivers to safely slow down; WHAT AMBER COMMUNICATES: Amber means: 'I am a school bus, I am about to stop, be prepared to stop behind me'; it does NOT yet require drivers to stop; it gives them time to recognize the bus, check their mirrors, and slow down before the red lights activate; SEQUENCE: AMBER lights → bus slows → stops at designated location → RED lights + STOP ARM extend → door opens → students load/unload → door closes → STOP ARM retracts → RED lights off → AMBER lights briefly → amber off → bus proceeds; DRIVER ERROR: Not activating amber lights early enough is a common error that increases the risk of rear-end crashes behind the stopped bus and does not give drivers enough warning to stop smoothly; SCHOOL BUS AWARENESS FOR ALL CMV DRIVERS: CDL drivers must know and follow school bus stopping laws — failure to stop when required for a school bus is a serious violation in all states.
Source: FMCSA CDL Manual, Chapter 12, School Buses, Amber Warning Lights