Skid Control, Hazard Perception, and Safe Operating Practices
Skid control and hazard perception questions test whether you can recognize conditions that cause loss of traction and manage space, speed, and visibility with a long, heavy combination vehicle.
Skid causes and correction
- Overbraking, excessive speed, abrupt steering, and poor traction cause skids.
- If a skid starts, release the brakes or accelerator as appropriate and steer in the direction you want to go.
- Avoid overcorrecting; a trailer skid may require releasing the brakes and pulling forward to straighten out.
- With ABS, keep firm brake pressure; do not pump.
Hazard perception
- Scan 12-15 seconds ahead and check mirrors often.
- Watch for low bridges, overhead clearance, sharp curves, construction, railroad crossings, pedestrians, and cyclists.
- Remember blind spots and trailer swing; a combination can strike objects beside it.
Safe operating
- Following distance: one second per 10 feet of vehicle length below 40 mph, plus one second above 40 mph. A 60-foot rig at 55 mph needs about 7 seconds.
- Slow before curves; rollover risk rises with speed and load height.
- Secure cargo and check clearance before moving.
Worked example
A 70-foot combination approaches a sharp off-ramp at 55 mph. The driver brakes hard in the curve; the trailer begins to skid. The correct action is to slow before the curve, release hard braking if traction is lost, and steer smoothly. Speed management before the curve is the real fix.
Traps
- Braking hard in a curve.
- Looking only at the tractor and ignoring trailer position.
- Following too closely for the vehicle's length.
- Forgetting overhead clearance and low bridges.