Maine CDL — General Knowledge practice
Maine CDL — General Knowledge: Signals & Pavement Markings practice test
How to read traffic signals, lane lines, and pavement markings — including yellow and white lines, arrows, and flashing lights.
Content reviewed against official driver handbooks · August 12, 2026
13 questions · pass with 10 correct. You get instant feedback and an explanation after every answer.
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12 sample Signals & Pavement Markings questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.
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1. During a walk-around you find a red side-marker light midway along the trailer's side. What does the inspection guide say about that color?
Correct answer: Only the rear side-markers should be red; the others should be amber
Side-marker lights and reflectors are red at the rear and amber everywhere else, so a red lamp at mid-length is the wrong color.
Source: Maine Commercial Driver License Manual — Section 2.1.5, Seven-step Inspection Method
2. You are in a crash and have moved your truck to the side of the road. Along with setting out reflective triangles, what does the manual tell you to switch on to protect the area?
Correct answer: Your flashers
Protecting the scene means getting the vehicle to the roadside if you can, putting on the flashers, and setting out triangles where other drivers will see them in time.
Source: Maine Commercial Driver License Manual — Section 2.20.1, Protect the Area
3. During the lights operations check, the examiner may watch the lamps from outside for you. What does the manual say you will need to do with the cab window?
Correct answer: Roll it down and speak loudly enough for the examiner to hear
You tell the examiner where to stand and exactly which lights to look at, so the window comes down and you speak up. A light you forget to name earns no credit.
Source: Maine Commercial Driver License Manual — Section 11.4, Lights Operations Check (All Vehicles)
4. On a two-lane road, what accompanies the painted "X" and "RR" ahead of a railroad crossing?
Correct answer: A no-passing marking
The pavement markings carry the same message as the advance warning sign. On two-lane roads they include a no-passing marking, and a no-passing-zone sign is posted as well.
Source: Maine Commercial Driver License Manual — Section 2.15.2, Warning Signs and Devices
5. On the inspection test, why must the horn be shown to work?
Correct answer: It lets you warn other road users that you are there and helps avoid collisions
The horn is how you alert cars, motorcyclists, bicyclists and pedestrians to your presence, so it has to function properly.
Source: Maine Commercial Driver License Manual — Section 11.1.1, In-Vehicle/Engine Start
6. On the road test you are driving a vehicle that displays placards. When do you switch on the four-way flashers for a railroad crossing?
Correct answer: As the vehicle approaches the crossing
Drivers of buses, school buses and placarded vehicles turn on the four-way flashers during the approach, make the stop, and switch the flashers off after the vehicle has crossed.
Source: Maine Commercial Driver License Manual — Section 13.1.8, Railroad Crossing
7. When you shift by engine speed, which instrument do you watch to know when to shift up?
Correct answer: The tachometer
Shifting by engine speed means learning the engine's operating rpm range and upshifting when the tachometer shows the top of it.
Source: Maine Commercial Driver License Manual — Section 2.3.1, Manual Transmissions
8. Which of these is NOT on the manual's list of other lights and devices that must be clean and working so you can be seen at night?
Correct answer: Interior dome lights
The list is reflectors, marker lights, clearance lights, taillights and identification lights. The manual actually says to keep the cab's interior light off at night.
Source: Maine Commercial Driver License Manual — Section 2.11.4, Vehicle Factors
9. On the manual's oil pressure gauge illustration, what reading is normal with the engine idling?
Correct answer: 5 to 20 psi
The illustration gives 5-20 psi at idle and 35-75 psi when operating. Pressure that is low, dropping or fluctuating means stop right away.
Source: Maine Commercial Driver License Manual — Section 2.1.5, Seven-step Inspection Method
10. At the rear of the vehicle, what does the walk-around inspection say about license plates?
Correct answer: They should be present, clean and secured
The rear check covers lights, reflectors and the license plate or plates, which must be in place, clean and fastened.
Source: Maine Commercial Driver License Manual — Section 2.1.5, Seven-step Inspection Method
11. On a combination vehicle with ABS, what should the trailer's ABS light at the rear driver's side do when the vehicle is started?
Correct answer: Come on, then go off
As part of the lighting indicator check, the trailer's ABS light on the rear driver's side should turn on and then turn off, just as the dash ABS indicator does.
Source: Maine Commercial Driver License Manual — Section 11.1.1, In-Vehicle/Engine Start
12. While inspecting a bus's passenger entry, which light do you check if the bus has one?
Correct answer: The step light
At the entry you confirm the doors work, the handrails are secure and, where fitted, the step lights are working.
Source: Maine Commercial Driver License Manual — Section 11.2, Passenger and School Bus Only
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