Hazard Perception and Safe Driving Practices
Hazard perception and safe driving - what is tested
This domain tests following distance, space management, weather and night driving, downgrades, and railroad and work-zone decisions with a heavy combination.
Following distance
- Use one second for every 10 feet of vehicle length below 40 mph, and add one second above 40 mph.
- Add more for rain, fog, night, a heavy load, or a downgrade.
- If someone tailgates you, increase your own following distance; do not speed up.
Scanning
- Look about 15 seconds ahead in the city and a quarter mile down the highway; check mirrors every 5 to 8 seconds.
- Watch for shadows hiding potholes, ice on bridges and overpasses, and stopped traffic beyond a crest.
- At night, slow to a speed at which you can stop within the distance your headlights show.
Weather and grades
- Fog: low beams, slow down, and never stop on the traveled portion of the road.
- Rain: hydroplaning risk rises with speed and with worn tires; back off.
- Downgrades: select a lower gear before you start down, use engine braking, and avoid fanning the brakes.
Crossings and work zones
- Never stop on railroad tracks; confirm room on the far side before crossing, and do not shift while crossing.
- In work zones, reduce speed, watch flaggers and merging traffic, and expect narrow lanes and sudden stops.
Worked example
A 70-foot combination traveling 55 mph: 70 divided by 10 gives 7 seconds, plus 1 second for speed over 40 mph, for an 8-second gap. At 55 mph you cover about 80 feet per second, so the gap is roughly 640 feet. If fog limits visibility to 300 feet, you must slow until you can stop within 300 feet rather than simply holding the gap.
Traps
- Applying a car's 3-second rule to a 70-foot rig.
- Using high beams in fog.
- Braking hard in a curve instead of slowing before it.
- Assuming a green light means the intersection is clear.