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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. An item that is 15 feet long placed on a flatbed trailer should have at least:
1 tie-down.
15 tie-downs.
3 tie-downs.
2 tie-downs.
2. When driving at night, you should use ________ when you can.
low beams
emergency flashers
indicator lights
high beams
3. If you go twice as fast, your stopping distance will increase by:
eight times.
four times.
ten times.
two times.
4. When approaching a double railroad track, you should:
rely upon the presence of warning signals.
remember that a train on one track may hide a train on the other track.
remember that trains may be more frequent.
expect to hear a train when it's approaching.
5. The earliest way to recognize that your trailer has started to skid is:
by releasing the brakes.
by checking your mirrors.
by hearing squeaking noises from the wheels.
by checking the jackknife sensor.
6. With low beams, drivers can see ahead about:
15 feet
250 feet
150 feet
100 feet
7. If you cannot make a right turn without entering another traffic lane, you should:
turn wide as you complete the turn.
turn wide before you start the turn.
watch out for vehicles coming toward you and back up for them.
swing wide to the left before starting the turn.
8. On front tires, tread should be at least:
4/16 inch
4/32 inch
1/16 inch
2/32 inch
9. Your mirrors should be adjusted so that:
the rear of the vehicle is visible in the mirror.
no part of the vehicle is visible in the mirror.
a part of the vehicle is visible in the mirror.
more than half of the mirror shows the vehicle.
10. An alcohol evaporator:
to hold compressed air.
protects the air brake system from too much pressure.
is used to reduce the risk of ice in air brake valves and other parts during cold weather.
used to reduce the chance of the front wheels skidding.
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Doubles Triples DC CDL Test

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