Passenger Vehicle Braking, Skid Control, and Hazard Perception
What this domain tests
This domain tests speed and space management in a heavy passenger vehicle: how to brake without locking wheels, how to recover from a skid, and how to scan for hazards that arrive faster than a bus can stop. Expect questions on brake fade, following distance, and steering in a skid.
Core rules
- Brake early and smoothly. In an air-brake bus, do a brake check before the trip and use controlled braking; if wheels lock, release and reapply rather than holding the pedal down.
- Downshift before a downgrade. Do not ride the brakes; brake fade leaves you with no stopping power. Use the same gear down that you used up.
- Skid recovery: steer in the direction you want the vehicle to go. If the rear wheels skid, release the brake and steer into the skid; if the front wheels skid, straighten the wheel and release the brake. Avoid hard acceleration and overcorrection.
- Following distance: use at least one second per 10 feet of vehicle length, plus one second above 40 mph. A 40-foot bus at 55 mph needs about 5 seconds.
- Hazard perception: scan 12–15 seconds ahead, check mirrors at stops, watch for standees moving before the bus stops, and identify escape routes before you need them.
Worked example
A 40-foot bus descends a wet hill at 45 mph. The driver brakes late, the rear starts to swing right, and the bus begins to skid. The driver releases the brake, steers right into the skid to align the rear, then straightens and brakes gently. Reasoning: the rear wheels have lost traction; holding the brake or steering left would increase the rotation. The correct response is to restore rolling traction, then slow gradually.
Traps
- Braking hard in a curve or on wet pavement.
- Steering away from a skid.
- Using the parking brake to stop a moving bus.
- Following a 40-foot bus at a 2-second gap.
- Ignoring low-clearance signs or passengers standing before a stop.