Commercial driver’s license (CDL) knowledge tests · California DMV
Seeing and communicating
Questions and answers
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How far ahead do most good drivers look?
At least 12 to 15 seconds
Good drivers look ahead to where they will be in 12 to 15 seconds.
Section 2 · 2.4.1 – Seeing Ahead ↗ -
At lower speeds in the city, about how far is 12 to 15 seconds ahead?
About one block
At lower speeds, 12 to 15 seconds is roughly one block.
Section 2 · 2.4.1 – Seeing Ahead ↗ -
At highway speeds, about how far is 12 to 15 seconds ahead?
About a quarter of a mile
At highway speeds, 12 to 15 seconds is about a quarter of a mile.
Section 2 · 2.4.1 – Seeing Ahead ↗ -
What may happen if you do not look far enough ahead?
You may have to stop too quickly or make quick lane changes
Stopping and changing lanes take a lot of distance, so short sight lines force sudden moves.
Section 2 · 2.4.1 – Seeing Ahead ↗ -
Does looking 12 to 15 seconds ahead mean you can ignore things that are closer?
No, shift your attention back and forth between near and far
Good drivers keep moving their attention back and forth, near and far.
Section 2 · 2.4.1 – Seeing Ahead ↗ -
A traffic light ahead has been green for a long time. What should you do?
Start slowing down and be ready to stop
A light that has been green a long while will probably change before you reach it.
Section 2 · 2.4.1 – Seeing Ahead ↗ -
When looking ahead for traffic, what should you watch for?
Vehicles entering the highway, moving into your lane, or turning, and brake lights
Seeing these things early lets you adjust speed or change lanes in good time.
Section 2 · 2.4.1 – Seeing Ahead ↗ -
What road conditions should you look for ahead?
Hills, curves, and anything else that will make you slow or change lanes
Look for hills and curves, and pay attention to traffic signals and signs.
Section 2 · 2.4.1 – Seeing Ahead ↗ -
How many mirrors must every California registered motor vehicle have?
At least 2, including 1 on the left-hand side
At least 2 mirrors are required, one of them on the left-hand side.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
The required mirrors must show the roadway to the rear for at least what distance?
200 feet
The mirrors must give a clear view to the rear for at least 200 feet.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
Your load blocks the view straight to the rear. Which mirrors are required?
Both left and right-hand rear view mirrors
Both side mirrors are required when the vehicle, its load, or a towed vehicle hides the rear view.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
How should you look at your mirrors while driving on the road?
Quickly, looking back and forth between the mirrors and the road ahead
Check mirrors quickly and understand what you see. Staring too long means travelling a distance without watching ahead.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
How do objects look in a convex mirror?
Smaller and farther away than they really are
A convex mirror shows a wider area, but things look smaller and farther off, so allow for it.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
What is the advantage of a convex mirror over a flat mirror?
It shows a wider area
Curved mirrors show a wider area than flat mirrors, though blind spots remain.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
When should mirror adjustment be checked?
Before the start of any trip, with the trailer straight
Mirrors are checked before a trip and can be checked accurately only when the trailers are straight.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
When adjusting a mirror, what should it show?
Some part of the vehicle, as a reference point
Seeing part of the vehicle gives a reference for judging where other things are.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
Besides traffic, what can regular mirror checks help you spot on your own vehicle?
A tire fire or loose cargo straps
Mirrors let you watch the tires, which is one way to spot a tire fire, and check open cargo for loose straps, ropes, or chains.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
Do mirrors show everything around your vehicle?
No, there are blind spots that mirrors cannot show
There are blind spots the mirrors cannot show, so check regularly to see who is moving into them.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
Which situations call for more than regular mirror checks?
Lane changes, turns, merges, and tight maneuvers
These four special situations need extra mirror checks.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
You have signaled for a lane change. Why check your mirrors again?
To see that no one has moved into your blind spot
After signaling, check that nobody has moved into the blind spot.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
At how many points in a lane change does the handbook tell you to check your mirrors?
Four: before, after signaling, right after starting, and after completing it
Check before the change, after signaling, right after starting, and after completing it.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
Why check your mirrors while turning?
To make sure the rear of your vehicle will not hit anything
In turns, the mirrors show whether the rear of the vehicle is clearing obstacles.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
What do you use your mirrors for when merging?
To make sure the gap in traffic is large enough to enter safely
When merging, the mirrors tell you whether the gap is big enough.
Section 2 · 2.4.2 – Seeing to the Sides and Rear ↗ -
Why should you signal well before a turn?
It is the best way to keep others from trying to pass you
Signaling early is the best way to stop others from trying to pass as you turn.
Section 2 · 2.5.1 – Signal Your Intentions ↗ -
When may you cancel your turn signal?
After you have completed the turn
Signal continuously and do not cancel until the turn is complete. You need both hands on the wheel to turn safely.
Section 2 · 2.5.1 – Signal Your Intentions ↗ -
Your vehicle does not have self-canceling signals. What must you remember after a turn?
To turn the signal off
Without self-canceling signals, turn the signal off yourself after the turn.
Section 2 · 2.5.1 – Signal Your Intentions ↗ -
Why change lanes slowly and smoothly?
A driver you did not see may have a chance to honk or avoid you
A slow, smooth lane change gives an unseen driver time to warn you or get clear.
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How can you warn drivers behind you that you are about to slow down?
A few light taps on the brake pedal to flash the brake lights
Light taps on the brake pedal flash the brake lights and warn following drivers.
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When should you use the 4-way emergency flashers on the road?
When you are driving very slowly or are stopped
The flashers are for times when you are moving very slowly or stopped.
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You are about to make a tight turn in a large vehicle. How do you warn the drivers behind?
Brake early, slowly, and gradually
Most car drivers do not know how slowly a large vehicle must take a tight turn, so brake early and gradually.
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You see a hazard ahead that drivers behind you cannot see past your vehicle. What should you do?
Flash your brake lights to warn them
Your vehicle may hide hazards from those behind, so warn them by flashing the brake lights.
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Another driver is waiting behind you to pass. Should you signal when it is safe for them?
No, do not direct traffic, because it could cause an accident and you could be blamed
Signaling others to pass could cause an accident for which you might be blamed.
Section 2 · 2.5.1 – Signal Your Intentions ↗ -
You are about to pass a pedestrian or bicyclist. What should you assume?
That they do not see you
Assume they do not see you, because they could suddenly move in front of you.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
When it is legal, how can you let someone know you are about to pass at night?
Flash your lights from low to high beam and back
Tap the horn lightly, or at night flash from low to high beam and back.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
At dawn, dusk, in rain, or snow, which lights should you turn on?
The headlights, on low beam
Use the headlights, not just the marker lights, and keep them on low beam.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
Why use low beams and not high beams when it is hard to see in the daytime?
High beams can bother people in the daytime as well as at night
High beams can bother other people by day as well as by night.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
You pull off the road and stop. What should you turn on?
The 4-way emergency flashers
Turn on the 4-way flashers. Taillights alone are not a trustworthy warning.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
Why not rely on taillights alone when parked at the side of the road?
Drivers have hit parked vehicles because they thought they were moving normally
Drivers have crashed into the rear of parked vehicles they took to be moving.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
You must stop on the shoulder of a road. How soon must your emergency warning devices be out?
Within 10 minutes
Warning devices go out within 10 minutes of stopping on a road or shoulder.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
You stop on a one-way or divided highway. Where do the warning devices go?
10 feet, 100 feet, and 200 feet toward the approaching traffic
On a one-way or divided highway all three devices go toward approaching traffic at 10, 100, and 200 feet.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
You stop on a 2-lane road with traffic in both directions. Where do the warning devices go?
Within 10 feet of the front or rear corners, and 100 feet behind and ahead
On a two-way or undivided road, one device marks the vehicle and the others go 100 feet behind and ahead.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
You stop just past a hill that hides your vehicle from drivers coming up behind. What do you do with the rearmost triangle?
Move it back down the road so it gives warning
If a hill or curve blocks the view within 500 feet, the rearmost device is moved back beyond the obstruction.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
An obstruction counts for warning device placement when it keeps drivers from seeing your vehicle within what distance?
500 feet
Place a device back beyond any hill, curve, or obstruction that hides the vehicle within 500 feet.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
How should you carry the triangles when setting them out?
Between yourself and the oncoming traffic
Holding them between you and oncoming traffic makes you visible to other drivers.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
What does the handbook say about using your horn?
Use it when needed, because it can startle others when used unnecessarily
The horn can help avoid an accident, but it can startle people and be dangerous when used without need.
Section 2 · 2.5.2 – Communicating Your Presence ↗ -
You must drive well below the speed of traffic. How do you alert drivers coming up behind?
Turn on the emergency flashers, if it is legal
Following drivers often misjudge how fast they are closing on a slow vehicle. Flasher laws differ from state to state.
Section 2 · 2.5.1 – Signal Your Intentions ↗
Questions and answers by topic
- Licenses, endorsements and tests105
- Disqualifications and state rules110
- Vehicle inspection80
- Basic control and shifting gears47
- Controlling your speed62
- Managing space40
- Seeing hazards49
- Distracted and Aggressive Driving71
- Night, Fog, Winter and Hot Weather124
- Railroad Crossings and Mountain Driving65
- Emergencies, ABS and Skids102
- Accident Procedures and Fires49
- Alcohol, Drugs and Illness41
- Hazardous Materials Rules for All Drivers42
- Transporting Cargo Safely79
- Bus Inspection, Loading and Hazardous Materials74
- Driving a Bus: Stops, Crossings and Prohibited Practices56
- Air Brake Parts: Compressor, Tanks and Foundation Brakes52
- Warnings, Spring Brakes, ABS and Dual Systems59
- Inspecting Air Brake Systems61
- Using Air Brakes51
- Driving Combination Vehicles Safely50
- Combination Vehicle Air Brakes and ABS59
- Coupling and Uncoupling63
- Inspecting a Combination Vehicle24
- Pulling Double and Triple Trailers16
- Coupling, Inspecting and Brake Checks for Doubles34
- Tank Vehicles62
- HazMat basics and who does what48
- Hazard classes, labels and lists64
- Shipping papers and package markings49
- Placards and placard tables40
- Loading and unloading HazMat58
- Bulk packaging and tanks30
- HazMat driving and parking rules72
- HazMat emergencies and reporting60
- Danger zones and mirrors34
- Loading and unloading students47
- Emergency exit and evacuation34
- Railroad-highway crossings40
- Student management, ABS and special situations47