CDL · On the Road

When driving a bus, why is speed management on curves especially important?

Correct answer

Buses have a high center of gravity (especially with passengers and baggage above seating level) and can roll over more easily than passenger cars in curves

  1. A Buses have unique speedometers
  2. B Buses have a high center of gravity (especially with passengers and baggage above seating level) and can roll over more easily than passenger cars in curves
  3. C Buses cannot turn at all
  4. D Speed only matters on straight roads

Why this is the answer

Modern motorcoaches and buses have high centers of gravity because the passenger compartment is well above the chassis and baggage is loaded high in some configurations. The combination makes rollover possible in curves taken too fast. Posted advisory speeds on curves are designed for passenger cars; buses (especially loaded ones) should be 10-15 mph below the advisory on tight off-ramps and curves. Brake before the curve, maintain steady speed through it, accelerate gently after exit. Bus rollovers in curves and on highway off-ramps have produced multi-fatality outcomes; the prevention is conservative speed and smooth driving.
Source: FMCSA CDL Manual 4.3.4 Speed in Curves

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