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Safely pulling double and triple trailers requires knowledge and skill. If you want to pull double or triple trailers, you must add the Doubles/Triples (T) endorsement to your Class A CDL. The District of Columbia doubles triples test consists of 20 questions. To pass, you must correctly answer at least 16 questions (80%). The DC CDL doubles triples test covers the following sections of the District of Columbia CDL Manual: Driving Safely, Air Brakes (if you plan to operate vehicles equipped with air brakes), Combination Vehicles, Doubles and Triples. Take this DC CDL practice test now to prepare for the actual test!
1. When the spring brakes are on, you should:
not push the brake pedal down.
press the accelerator.
exceed the posted speed limit.
pump the brakes.
2. When more cargo is piled up in a truck, the center of gravity moves:
higher up from the road.
to the left side of the truck.
closer to the ground.
to the right side of the truck.
3. Having ABS on only the trailer:
is very dangerous.
makes the trailer more likely to swing out.
still gives you more control over your vehicle during braking.
makes the trailer more likely to roll over.
4. Emergency brakes must be held on by:
mechanical force.
hydraulic pressure.
air pressure.
dynamic pressure.
5. If you must drive slowly, how should you alert following drivers?
Help them out by signaling when it is safe to pass
Use your emergency flashers if it is legal
Turn on your taillights
Flash your brake lights
6. Truck tractors with air brakes built after March 1, 1997, are required to be equipped with:
anti-lock brakes.
hydraulic brakes.
a rear backup camera.
7. Watch out for black ice:
any time the temperature is below freezing and the road looks wet.
when it is snowing.
right after it starts to rain.
when the temperature is above freezing and the road is dry.
8. When driving a double or triple:
all trailers should have the same weight.
the more heavily loaded trailer should be in the rear.
the more heavily loaded trailer should be directly behind the tractor.
the lighter trailer should be directly behind the tractor.
9. If you're feeling tired while driving you should:
drink coffee.
stop driving and get some rest.
eat something.
increase your speed to get to your destination quicker.
10. If an item placed on a flatbed trailer is 7 feet long, it should have __ tie-downs.
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DC CDL Doubles Triples Test

Number of questions: 20
Correct answers to pass:16
Passing score:80%
Number of questions: 20
Correct answers to pass:16
Passing score:80%
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