Commercial driver’s license (CDL) knowledge tests · California DMV
Managing space
Questions and answers
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Why does a driver need space all around the vehicle?
When things go wrong, space gives time to think and act
Space gives you time to think and take action when something goes wrong.
Section 2 · 2.7 – Managing Space ↗ -
Of all the space around your vehicle, which is the most important?
The space ahead, which you are driving into
The area you are driving into matters most.
Section 2 · 2.7.1 – Space Ahead ↗ -
The vehicle ahead of you is smaller than yours. What does that mean for stopping?
It can probably stop faster than you can
A smaller vehicle can usually stop faster, so following closely risks a crash.
Section 2 · 2.7.1 – Space Ahead ↗ -
Below 40 mph, how much following distance does the handbook’s rule call for?
At least 1 second for each 10 feet of vehicle length
Allow at least 1 second per 10 feet of vehicle length below 40 mph.
Section 2 · 2.7.1 – Space Ahead ↗ -
How does the following distance rule change at speeds above 40 mph?
Add 1 second
Above 40 mph, use the same formula and add 1 second for safety.
Section 2 · 2.7.1 – Space Ahead ↗ -
You drive a 40-foot vehicle at 30 mph. How many seconds should you leave between you and the vehicle ahead?
4 seconds
Forty feet at one second per 10 feet is 4 seconds below 40 mph.
Section 2 · 2.7.1 – Space Ahead ↗ -
You drive a 40-foot vehicle at 55 mph. How many seconds of following distance do you need?
5 seconds
Four seconds for the length plus one more above 40 mph makes 5 seconds.
Section 2 · 2.7.1 – Space Ahead ↗ -
You drive a 60-foot rig at 50 mph. How many seconds of following distance do you need?
7 seconds
Six seconds for the length plus one more above 40 mph makes 7 seconds.
Section 2 · 2.7.1 – Space Ahead ↗ -
How do you measure your following distance on the road?
Count the seconds from when the vehicle ahead passes a landmark until you reach it
Pick a shadow, pavement marking, or other landmark and count “one thousand-and-one, one thousand-and-two” until you reach it.
Section 2 · 2.7.1 – Space Ahead ↗ -
In a 40-foot truck at 35 mph you count only 2 seconds behind the vehicle ahead. What should you do?
Drop back and count again until you have 4 seconds
Two seconds is too close for a 40-foot truck. Drop back to 4 seconds.
Section 2 · 2.7.1 – Space Ahead ↗ -
How does a slippery road affect the space you need ahead?
You need more space to stop
When the road is slippery, more space is needed to stop.
Section 2 · 2.7.1 – Space Ahead ↗ -
A heavy load is slowing you down on an uphill grade. Where should you drive?
In the right lane, if you can
Heavy vehicles are often tailgated when they cannot keep up, so stay to the right.
Section 2 · 2.7.2 – Space Behind ↗ -
Going uphill, when is it acceptable to pass another slow vehicle?
Only when you can get around quickly and safely
Do not pass another slow vehicle uphill unless you can get around it quickly and safely.
Section 2 · 2.7.2 – Space Behind ↗ -
In which conditions are you especially likely to be tailgated?
When you are traveling slowly and in bad weather
Drivers stuck behind slow vehicles follow closely, and many small vehicles follow large ones closely in bad weather.
Section 2 · 2.7.2 – Space Behind ↗ -
You are being tailgated. What should you do about the space in front of you?
Increase your following distance
More room ahead helps you avoid sudden changes and makes it easier for the tailgater to get around.
Section 2 · 2.7.2 – Space Behind ↗ -
A vehicle is following you very closely. Should you speed up?
No, it is safer to be tailgated at a low speed than a high speed
Do not speed up. Being tailgated at low speed is the safer of the two.
Section 2 · 2.7.2 – Space Behind ↗ -
Which is the wrong way to deal with a tailgater?
Flashing your brake lights or switching on your taillights
Avoid tricks such as turning on the taillights or flashing the brake lights.
Section 2 · 2.7.2 – Space Behind ↗ -
You are being tailgated and need to slow down or turn. How should you do it?
Signal early and reduce speed very gradually
Avoid quick changes. Signal early and slow very gradually.
Section 2 · 2.7.2 – Space Behind ↗ -
How do you keep a safe clearance on both sides in your lane?
Keep the vehicle centered in the lane
A centered vehicle keeps clearance on either side. A wide vehicle has little room to spare.
Section 2 · 2.7.3 – Space to the Sides ↗ -
What are the two dangers of traveling alongside other vehicles?
Another driver may turn into you, and you may be trapped when you need to change lanes
A driver beside you may change lanes suddenly, and you may have nowhere to go when you need to move.
Section 2 · 2.7.3 – Space to the Sides ↗ -
Traffic is heavy and you must travel near other vehicles. What should you do?
Keep as much space as possible and drop back or pull forward so the other driver can see you
Keep what space you can, and shift your position so you are sure the other driver can see you.
Section 2 · 2.7.3 – Space to the Sides ↗ -
Where can strong winds be an especially bad problem?
Coming out of tunnels
Strong winds make it hard to stay in your lane, usually more so for lighter vehicles, and can be especially bad coming out of tunnels.
Section 2 · 2.7.3 – Space to the Sides ↗ -
Can you trust the height posted at a bridge or overpass?
Not fully, since repaving or packed snow may have reduced the clearance
Do not assume posted heights are correct. Repaving or packed snow may have cut the clearance since posting.
Section 2 · 2.7.4 – Space Overhead ↗ -
Your cargo van cleared a bridge when loaded. Will it clear the same bridge when empty?
Not necessarily, because an empty van is higher than a loaded one
The weight of the cargo changes the van’s height. An empty van rides higher.
Section 2 · 2.7.4 – Space Overhead ↗ -
You are not sure your vehicle will fit under an overhead object. What should you do?
Go slowly, and take another route if you are not sure you can make it
If in doubt go slowly, and if you are not sure you can make it, take another route.
Section 2 · 2.7.4 – Space Overhead ↗ -
The road tilts your vehicle toward signs and trees at the edge. What should you do?
Drive a little closer to the center of the road
Where a tilting road brings the top of the vehicle near roadside objects, move a little toward the center.
Section 2 · 2.7.4 – Space Overhead ↗ -
What should you do before backing into an area?
Get out and check for overhanging objects such as branches or electric wires
Overhead objects are easy to miss while backing, so get out and check first.
Section 2 · 2.7.4 – Space Overhead ↗ -
When can the space under your vehicle be very small?
When the vehicle is heavily loaded
Clearance underneath shrinks with a heavy load, which is often a problem on dirt roads and unpaved yards.
Section 2 · 2.7.5 – Space Below ↗ -
What can drainage channels across a road do to some vehicles?
Cause the ends of the vehicle to drag
Drainage channels can make the ends of some vehicles drag, so cross them carefully.
Section 2 · 2.7.5 – Space Below ↗ -
Which vehicles are most at risk of getting hung up on railroad tracks?
Those pulling trailers with a low underneath clearance
Railroad tracks are a particular problem for trailers with low clearance underneath.
Section 2 · 2.7.5 – Space Below ↗ -
Why can large vehicles hit other vehicles or objects during turns?
Because of wide turning and off-tracking
Wide turning and off-tracking make the space around a truck or bus important in turns.
Section 2 · 2.7.6 – Space for Turns ↗ -
Your truck cannot make a right turn without swinging into another lane. When should you turn wide?
As you complete the turn
Turn wide as you complete the turn and keep the rear close to the curb.
Section 2 · 2.7.6 – Space for Turns ↗ -
During a right turn, why keep the rear of your vehicle close to the curb?
It stops other drivers from passing you on the right
A rear kept near the curb leaves no room for someone to slip past on the right.
Section 2 · 2.7.6 – Space for Turns ↗ -
What may happen if you swing wide to the left as you start a right turn?
A following driver may think you are turning left and try to pass on the right
A driver behind may misread the move, pass on the right, and be hit as you complete the turn.
Section 2 · 2.7.6 – Space for Turns ↗ -
You have crossed into the oncoming lane to complete a turn and a vehicle is coming toward you. What should you NOT do?
Back up for it
Give oncoming vehicles room to go by or stop, but do not back up, because you might hit someone behind you.
Section 2 · 2.7.6 – Space for Turns ↗ -
On a left turn, where should you be before you start turning?
At the center of the intersection
Reach the center of the intersection first. Turning too soon can make the left side hit another vehicle because of off-tracking.
Section 2 · 2.7.6 – Space for Turns ↗ -
You are turning left and there are 2 turning lanes. Which should you take?
The right turn lane of the two
Take the right-hand turn lane. From the inside lane you may have to swing right, and drivers on your left are easier to see.
Section 2 · 2.7.6 – Space for Turns ↗ -
Compared with a car, what size of gap may a large vehicle need to enter traffic?
A much larger gap
Slow acceleration and the space a large vehicle takes mean a much larger gap is needed.
Section 2 · 2.7.7 – Space Needed to Cross or Enter Traffic ↗ -
Your vehicle is heavily loaded. How does that affect the room you allow when entering traffic?
Allow more room, because acceleration varies with the load
A heavy load slows acceleration, so allow more room.
Section 2 · 2.7.7 – Space Needed to Cross or Enter Traffic ↗ -
Before you start across a road, what must you be sure of?
That you can get all the way across before traffic reaches you
Make sure the whole vehicle can clear the road before traffic arrives.
Section 2 · 2.7.7 – Space Needed to Cross or Enter Traffic ↗
Questions and answers by topic
- Licenses, endorsements and tests105
- Disqualifications and state rules110
- Vehicle inspection80
- Basic control and shifting gears47
- Seeing and communicating46
- Controlling your speed62
- 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