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Seeing: looking ahead and using your mirrors

General Knowledge3 minManual section 2.4

Not looking properly is a major cause of crashes. A safe driver knows what is happening on every side. This lesson covers how far ahead to look, what to look for, mirror adjustment, regular and special mirror checks, and convex mirrors.

Seeing ahead (2.4.1)

All drivers look ahead, but many do not look far enough ahead. Stopping or changing lanes in a big vehicle takes a lot of distance, so you need to see problems early.

How far? Most good drivers look at least 12 to 15 seconds ahead — the distance you will cover in 12–15 seconds. At lower (city) speeds that is about one block. At highway speeds it is about a quarter of a mile.

If you do not look that far, you may have to stop too quickly or make quick lane changes.

Looking far ahead does not mean ignoring things close to you. Good drivers shift their attention back and forth, near and far.

What to look for ahead

The two main things to look for ahead are traffic and road conditions.

  • Traffic: vehicles entering the highway, moving into your lane, or making turns. Watch for the brake lights of vehicles that are slowing. Seeing these early lets you change speed or change lanes.
  • Stale green light: a light that has already been green for a long while will likely turn before you reach it. Ease off, begin slowing, and be prepared to stop.

Mirrors: adjustment and how to use them (2.4.2)

Your mirrors are your most important way to see the sides and rear. Check them regularly, and more often in special situations.

Adjustment: check mirror adjustment before every trip. It can only be checked accurately when the trailer(s) are straight. Adjust each mirror so it shows some part of your own vehicle — that gives you a reference point for judging where other things are.

Use: check mirrors quickly and understand what you see. Look back and forth between the mirrors and the road ahead. Do not stare at the mirrors, or you travel a long way without knowing what is happening in front.

Regular checks and special situations

Regular checks — traffic: look for vehicles on both sides and behind. In an emergency you may need to know if a quick lane change is possible. Spot overtaking vehicles. Mirrors have blind spots, so check often to see when vehicles move into them.

Regular checks — your vehicle: watch your tires (one way to spot a tire fire). With open cargo, look for loose straps, ropes or chains and a flapping or ballooning tarp.

Special situations need more than regular checks: lane changes, turns, merges and tight maneuvers.

  • Lane changes — check mirrors: before you change lanes (enough room?), after you signal (has anyone moved into your blind spot?), right after you start the change (path still clear?), and after you finish.
  • Turns — check that the rear of your vehicle will not hit anything.
  • Merges — make sure the gap in traffic is big enough.
  • Tight maneuvers — in close quarters, check mirrors often for clearance.

Convex mirrors

Many large vehicles have curved convex mirrors (also called fisheye, spot or bug-eye mirrors). They show a wider area than flat mirrors, which helps.

But in a convex mirror everything looks smaller and farther away than it really is. Remember this and allow for it — that car may be much closer than it looks.

References and scope

The topic reference is listed below. Sources support verification; the lesson itself is here. The current content needs technical and language review before public launch.

Manual reference: 2.4

Official CDL handbook · Utah ↗StatesOur editorial approach

Put it into practice

Educational questions with explanations. The answer review also works without the interactive quiz.

Preparing your questions…

Review questions with answers

  1. How far ahead do most good drivers look?
    1. 3 to 4 seconds
    2. 5 to 8 seconds
    3. 12 to 15 seconds
    4. 30 to 40 seconds
    Show answer
    12 to 15 seconds

    Good drivers look at least 12 to 15 seconds ahead.

  2. At highway speeds, looking 12 to 15 seconds ahead equals about:
    1. One block
    2. A quarter of a mile
    3. One mile
    4. 100 feet
    Show answer
    A quarter of a mile

    At highway speed, 12–15 seconds is about a quarter mile; at low speed, about one block.

  3. At lower (city) speeds, 12 to 15 seconds ahead is about:
    1. One block
    2. A quarter of a mile
    3. Half a mile
    4. Two car lengths
    Show answer
    One block

    At low speeds, 12 to 15 seconds is about one block.

  4. A traffic light ahead has been green for a long time. What should you do?
    1. Speed up to make it through
    2. Keep your speed and sound the horn
    3. Change lanes
    4. Start slowing down and be ready to stop
    Show answer
    Start slowing down and be ready to stop

    A stale green light will probably change before you get there.

  5. Looking 12 to 15 seconds ahead means you should:
    1. Ignore things close to your vehicle
    2. Shift your attention back and forth, near and far
    3. Look only at the vehicle directly ahead
    4. Stop checking your mirrors
    Show answer
    Shift your attention back and forth, near and far

    Good drivers keep switching attention between near and far.

  6. Which tool is most important for watching the areas beside and behind your vehicle?
    1. Turning your head
    2. Asking a passenger
    3. Your mirrors
    4. A backup camera
    Show answer
    Your mirrors

    Mirrors are the main tool for seeing to the sides and rear.

  7. Mirror adjustment can only be checked accurately when:
    1. The trailer(s) are straight
    2. The vehicle is in a turn
    3. The engine is off
    4. It is dark
    Show answer
    The trailer(s) are straight

    Check and adjust mirrors before every trip with the trailer straight.

  8. Each mirror should be adjusted so that:
    1. It shows only the road behind
    2. It points at the sky
    3. It shows the lane two lanes over
    4. It shows some part of your vehicle as a reference point
    Show answer
    It shows some part of your vehicle as a reference point

    Seeing part of your own vehicle gives a reference point for judging other images.

  9. Compared to a flat mirror, objects in a convex mirror look:
    1. Larger and closer
    2. Smaller and farther away than they really are
    3. The same size and distance
    4. Upside down
    Show answer
    Smaller and farther away than they really are

    Convex mirrors show a wider area but make things look smaller and farther away.

  10. During a lane change, when should you check your mirrors?
    1. Only before you signal
    2. Only after you finish
    3. Before the change, after signaling, right after starting, and after completing it
    4. Only if you hear a horn
    Show answer
    Before the change, after signaling, right after starting, and after completing it

    The manual lists four mirror checks for a lane change.

  11. Checking your mirrors regularly can help you spot:
    1. A tire fire
    2. Low engine oil
    3. A loose fan belt
    4. Low coolant
    Show answer
    A tire fire

    Watching your tires in the mirrors is one way to spot a tire fire.

  12. When using mirrors while driving, you should:
    1. Stare at them until you are sure
    2. Check them only once per hour
    3. Use only the convex mirror
    4. Check them quickly and look back and forth with the road ahead
    Show answer
    Check them quickly and look back and forth with the road ahead

    Do not focus on mirrors too long, or you travel a long way without seeing ahead.

  13. When carrying open cargo, what should you watch for in your mirrors?
    1. Exhaust smoke color
    2. Loose straps, ropes or chains and a flapping tarp
    3. The brake light bulbs
    4. The fuel cap
    Show answer
    Loose straps, ropes or chains and a flapping tarp

    Use mirrors to check open cargo: loose tie-downs or a flapping or ballooning tarp.

  14. Which is NOT one of the special situations that need more than regular mirror checks?
    1. Lane changes
    2. Merges
    3. Driving straight on an empty highway
    4. Tight maneuvers
    Show answer
    Driving straight on an empty highway

    Special situations are lane changes, turns, merges and tight maneuvers.

  15. The two main things to look for ahead are:
    1. Traffic and road conditions
    2. Billboards and exits
    3. Gas prices and rest areas
    4. Radio towers and bridges
    Show answer
    Traffic and road conditions

    Look ahead for traffic and for road conditions.

  16. When merging onto a highway, use your mirrors to make sure:
    1. Your trailer lights work
    2. The vehicle behind has its headlights on
    3. No one is tailgating you
    4. The gap in traffic is large enough to enter safely
    Show answer
    The gap in traffic is large enough to enter safely

    In a merge, mirrors confirm the gap is big enough.