Seeing: Practice Questions & Explanations

At highway speed, look 12 to 15 seconds ahead, which is roughly a quarter mile, or about one-quarter mile in good visibility. In city driving, 12 to 15 seconds is closer to one and a half blocks. The reason is reaction time: scanning far ahead lets you identify problems early enough to slow, change lanes, or stop without panic braking. Drivers who look only at the vehicle directly ahead get tunnel vision, react late, and tailgate. Looking only as far as the headlights at night is dangerous because at highway speed you can outrun your headlights — high beams reach about 350 feet, but at 55 mph you cover 80 feet per second, leaving little reaction time. The 12-to-15-second rule is independent of speed and works in any condition.

Effective mirror use means scanning regularly with brief glances, every 5 to 8 seconds while driving normally, and more often before any lane change or turn. Each scan should be a quick check, not a long stare, because your eyes need to return to the road ahead. Use both the flat (West Coast) mirror for accurate distance judgment and the convex (spot) mirror for wider angle. The flat mirror shows objects at their true size and distance; the convex makes them look smaller and farther away than they actually are, so do not judge gaps from a convex mirror alone. Both mirrors are needed because neither alone covers all the blind spots around a tractor-trailer. Adjust mirrors before driving so you can see the side of the trailer and the lane next to it.

Effective scanning on a long, straight road means keeping your gaze 12 to 15 seconds ahead — about a quarter mile at highway speed — while sweeping side to side and checking mirrors every 5 to 8 seconds. This gives you time to identify problems while they are still distant and to take smooth, planned action. Fixating on the vehicle directly ahead reduces your awareness of the bigger picture and leads to tailgating. Staring at the road just in front of the hood causes the eye to follow rapid motion and produces a tunnel-vision feeling, which can induce drowsiness. The speedometer should be glanced at periodically to confirm speed, not stared at. Active scanning is the difference between defensive driving and reactive driving.

EYE LEAD TIME is the practice of continuously scanning the road 12-15 seconds ahead of your vehicle. This is approximately one block in city driving and a quarter mile at highway speeds. WHY 12-15 SECONDS: At 55 mph, a vehicle travels about 80 feet per second. Perception-reaction time (seeing the hazard, deciding to brake, beginning to press the pedal) takes 1.5-2.5 seconds minimum. Braking distance for a loaded truck at 55 mph is approximately 300-400 feet. Total stopping distance therefore exceeds 400 feet. If you're only looking 2-3 seconds ahead (as many drivers instinctively do), you have no time to avoid a hazard — you're already in it. SCANNING TECHNIQUE: Look far ahead for major hazards; scan back to the area 6-8 seconds ahead for developing hazards; check mirrors every 5-8 seconds; use peripheral vision for immediate surroundings. CITY vs HIGHWAY: In the city, 12-15 seconds ahead may be only 1 block — look through and past intersections. On highways, a quarter mile gives you time to anticipate lane changes, merges, and slowdowns well before they become emergencies. MOST SERIOUS HAZARD: Rear-end crashes are the most common type in commercial trucking, and most result from following too closely or not looking far enough ahead.

A CMV driver relies heavily on mirrors because there is no rearward visibility through a solid-sided trailer. MIRROR SYSTEM ON A TRACTOR-TRAILER: (1) LEFT CONVEX MIRROR: Provides a wide-angle view of the area to the left and slightly behind the cab; shows left-lane traffic that may be alongside the trailer; essential for lane changes to the left; wide-angle distortion makes objects appear farther than they are; (2) RIGHT CONVEX MIRROR: Same function on the right side; covers the right side and right rear; right side has a much larger blind spot and this mirror is correspondingly more critical; (3) FLAT (REAR-VIEW) MIRRORS: Provide straight-back view along the side of the trailer; used for monitoring trailer position, detecting trailer tire issues, watching for fires or shifted cargo; (4) WIDE-ANGLE MIRRORS (WEST COAST STYLE): The large convex mirrors mounted high on tractor doors — provide the broadest view but with significant size distortion. MIRROR ADJUSTMENT: Before every trip, mirrors should be adjusted so the trailer's side is just visible in the inner edge of the mirror — this provides the reference point for judging gap. BLIND SPOTS: Even with properly adjusted mirrors, every CMV has blind spots: directly behind the trailer (cannot see any vehicle directly behind); directly alongside the cab (the 'right side' blind spot extending from the door back 20-30 feet); immediately in front of the cab. CHECK EVERY 5-8 SECONDS: Mirrors should be scanned in rotation continuously — don't fix attention on a single mirror.