District of Columbia (DC) CDL manual 2026
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- 1
Introduction
Everyone
You will lose your CDL for at least 60 days if you have committed two serious traffic violations within a three-year period involving a CMV.
This chapter has 26 more questions. Practice them in the app and see your pass chance.What is the penalty for a third railroad crossing violation within three years?
The sequence runs 60 days, then 120 days, then at least one year for the third violation inside a three-year period.
Manual section 1.3.5
A passenger endorsement is required to drive a vehicle designed to transport how many people?
The threshold is a vehicle designed to carry 16 or more passengers, and the driver counts toward that total.
Manual section 1.2
- 2
Driving Safely
Everyone
Texting means manually entering text into, or reading text from, an electronic device.
This chapter has 290 more questions. Practice them in the app and see your pass chance.What is the minimum tread depth required in every major groove on a front (steering) tire?
Front tires carry the steering load and must have at least 4/32 inch of tread in every major groove. Other tires need at least 2/32 inch.
Manual section 2.2
When does the manual tell you to be especially alert for drunk and sleepy drivers?
Late night is when both impairments are most common, so the clues to look for matter most in those hours.
Manual section 2.8.3
- 3
Transporting Cargo Safely
Everyone
Distribute the cargo so it is as low as possible; put the heaviest parts of the cargo under the lightest parts.
This chapter has 26 more questions. Practice them in the app and see your pass chance.What does axle weight measure?
Axle weight is what reaches the road through that axle or axle set, which is what bridge formulas and scales are concerned with.
Manual section 3.2.1
When is a high center of gravity most dangerous?
Both situations put sideways force into a load whose weight sits high. That is the combination that tips a vehicle over.
Manual section 3.2.3
- 4
Transporting Passengers
P endorsement (bus)
Drivers must know where the emergency exits are and how to operate them before an emergency occurs.
This chapter has 98 more questions. Practice them in the app and see your pass chance.You are driving a bus toward a railroad crossing where a stop is required. Within what distance range before the nearest rail must you stop?
Buses must stop between 15 and 50 feet before the nearest rail at railroad crossings where a stop is required. From there the driver looks and listens in both directions for a train.
Manual section 4.3
On buses designed to allow standing, how is the standee line marked?
A two-inch line on the floor, or some other equally clear means, shows riders how far forward they may stand.
Manual section 4.2.3
- 5
Air Brakes
Any vehicle with air brakes
To test the parking brake, stop the vehicle, put the parking brake on, and gently pull against it in a low gear to test that it will hold.
This chapter has 147 more questions. Practice them in the app and see your pass chance.How is a manually operated air tank drain valve worked?
Manual drains are built either as a quarter-turn valve at the bottom of the tank or as a valve operated by a cable the driver can reach.
Manual section 5.1.4
Besides a red warning light, what device do many air-braked vehicles use to alert the driver to low air pressure?
Low air pressure warning systems commonly pair a red light with an audible buzzer so the driver cannot miss the warning.
Manual section 5.1.11
- 6
Combination Vehicles
Class A
Pull-ups let a driver move forward and reposition the vehicle during backing whenever it drifts off course.
This chapter has 118 more questions. Practice them in the app and see your pass chance.What rearward amplification figure does the manual give for triples?
Triples come in at 3.5, meaning the last trailer can be rolled about three and a half times as easily as a five-axle tractor in the same quick maneuver.
Manual section 6.1.2
Your combination vehicle is equipped with ABS. How should you apply the brakes in a normal stop?
ABS only takes over when wheels are about to lock, so the driver should brake normally and let the system work in the background.
Manual section 6.3
- 7
Doubles and Triples
T endorsement
Keeping the lightest trailer at the rear reduces rollover and whip risk at the position of greatest sway.
This chapter has 98 more questions. Practice them in the app and see your pass chance.Among common commercial combinations, which is generally the most likely to whip and roll its rearmost trailer during a sudden maneuver?
The more trailers and hitch points a combination has, the more each steering input is amplified, and triples have the most of both.
Manual section 7.1
A converter dolly has no spring brakes. How do you release its brakes so it can be moved into position?
On a dolly without spring brakes, the brakes are held on by air stored in its tank. Opening the tank petcock bleeds that air off and frees the wheels.
Manual section 7.2.1
- 8
Tank Vehicles
N endorsement
Check manhole covers and vents; make sure the covers have gaskets and they close correctly, and keep the vents clear so they work correctly.
This chapter has 62 more questions. Practice them in the app and see your pass chance.Compared with most other kinds of cargo, why does a load of liquid in a tank make a truck easier to roll over?
A cargo tank places the load well above the pavement, giving the vehicle a high center of gravity. The higher the weight rides, the less sideways force it takes to tip the vehicle over.
Manual section 8.2
At a rest stop you notice product dripping from underneath your cargo tank. What should you do?
A leaking tank must not be driven; the vehicle stays put until the leak is properly addressed, because moving it spreads the product and the danger.
Manual section 8.1
- 9
Hazardous Materials
H endorsement
Table 2 lists ORM-D with no placard name.
This chapter has 234 more questions. Practice them in the app and see your pass chance.Hazardous materials rules are built around three broad goals. Which set below matches the intent of those rules?
The regulations exist to keep the product in its container, tell everyone what the hazard is, and make sure the people and equipment moving it are safe.
Manual section 9.1
On a portable tank holding less than 1,000 gallons, how tall must the shipping name letters be?
Below 1,000 gallons the letters may be one inch tall, half the height required on the larger portable tanks.
Manual section 9.5.1
- 10
School Buses
S endorsement
Before departing a stop, check mirrors to verify all students are clear of the bus and no one is running back toward it.
This chapter has 98 more questions. Practice them in the app and see your pass chance.How far can the blind spot behind a school bus extend, depending on the bus's size?
The rear blind spot runs from roughly 50 to 150 feet and can reach 400 feet on a longer, wider bus. Nothing in that space is visible without the side mirrors.
Manual section 10.1.3
While a school bus is being driven on its route, what is the rule for the emergency exit doors?
Emergency exit doors exist for evacuations only; while the bus is in operation they must be fully closed and secured.
Manual section 10.3
- 11
Pre-Trip Vehicle Inspection
Everyone (skills test)
Inspect that the battery box, cover, or door is secure, if applicable.
This chapter has 200 more questions. Practice them in the app and see your pass chance.What must be true of the lug nuts on every wheel?
Every nut must be there and tight. Rust trails or shiny threads around a nut are the signs that it has been working loose.
Manual section 11.5.2
How many parts make up the air brake check, and what happens if you get one wrong?
The air brake check has four parts, and failing to explain and demonstrate all four correctly is an automatic failure of the Vehicle Inspection test.
Manual section 11.1.2
What’s different in District of Columbia
Most of every state manual is the same federal material. These are the parts that are not.
- Low air warning in the air brakes chapter (written test): before pressure drops below 60 psi.
- A warning signal you can see must come on before the air pressure in the tanks falls below 60 psi.
The official District of Columbia CDL manual
Published free by District of Columbia Department of Motor Vehicles
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