Traffic Laws

Study questions with answers

4 sample Traffic Laws questions with the correct answer, a short explanation, and the official handbook reference. Read through them, then take the quiz above.

1. 1. A visible low-air-pressure warning must come on before tank pressure drops below what level?

   Correct answer: 55 psi

   Air brake vehicles must have a visible low-air warning that alerts you before tank pressure falls under 55 psi.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.1.11 - Low Air Pressure Warning

2. 2. Truck tractors with air brakes are required to have ABS if built on or after what date?

   Correct answer: March 1, 1997

   Air-braked truck tractors built on or after March 1, 1997 are required to have antilock brakes.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.1.16 - Antilock Braking Systems (ABS)

3. 3. How does an air brake system light up the brake lights for the drivers behind you?

   Correct answer: An air-pressure-operated electric switch turns them on as you brake

   An electric switch that is worked by air pressure turns the brake lights on when you apply the brakes.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.1.12 - Stop Light Switch

4. 4. Other air brake vehicles such as trucks, buses, trailers and converter dollies must have ABS if built on or after which date?

   Correct answer: March 1, 1998

   Other air-braked vehicles, including trucks, buses, trailers and dollies, must have ABS if built on or after March 1, 1998.

   Source: Pennsylvania Commercial Driver's Manual (PUB 223), Section 5.1.16 - Antilock Braking Systems (ABS)