Tennessee Electrical Contractor Exam –
Traffic Signal SystemsExam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. In a typical traffic signal system, which controller function is
responsible for determining the sequence and duration of signal
indications based on detected traffic demand and programmed timing
plans?
A. Load switch module
B. Conflict monitor unit
C. Signal controller unit
D. Flash transfer relay
C. Signal controller unit
The signal controller unit is the central processing device that
executes programmed timing plans and responds to detector inputs
to determine phase sequences and durations.
2. What is the primary purpose of a conflict monitor (malfunction
management unit) in a traffic signal cabinet?
A. To provide backup power during outages
B. To detect conflicting signal indications and place the system in flash
mode
C. To measure vehicle speed
, D. To synchronize signals across intersections
B. To detect conflicting signal indications and place the system in
flash mode
The conflict monitor ensures safety by detecting improper
simultaneous green signals and forcing the system into a safe
flashing mode.
3. Which type of detection system uses electromagnetic fields to sense
the presence of vehicles at an intersection?
A. Video detection
B. Infrared detection
C. Inductive loop detection
D. Microwave detection
C. Inductive loop detection
Inductive loop detectors are embedded in pavement and detect
vehicles through changes in electromagnetic fields caused by metal
objects.
4. What is the standard voltage level commonly used for traffic signal
indications in the United States?
A. 12 volts
B. 24 volts
C. 120 volts
D. 480 volts
C. 120 volts
Traffic signal indications typically operate at 120 volts AC, which is
standard for most signal equipment.
5. Which component converts low-voltage control signals from the
controller into high-voltage outputs for signal lamps?
A. Detector amplifier
B. Load switch
C. Conflict monitor
D. Flash relay
B. Load switch
, Load switches receive low-voltage signals and switch high-voltage
power to the signal lamps accordingly.
6. In a traffic signal system, what does “preemption” refer to?
A. Normal signal timing adjustment
B. Emergency vehicle override of normal signal operation
C. Pedestrian crossing activation
D. Backup power activation
B. Emergency vehicle override of normal signal operation
Preemption allows emergency vehicles to override normal signal
timing to receive a green indication for faster and safer passage.
7. Which device is typically used to provide battery backup during a
power outage at a signalized intersection?
A. Transformer
B. UPS system
C. Load center
D. Relay module
B. UPS system
Uninterruptible Power Supply (UPS) systems maintain signal
operation during power outages to ensure safety.
8. What is the purpose of a pedestrian push button in a traffic signal
system?
A. To control vehicle speed
B. To activate pedestrian crossing phases
C. To override the controller
D. To test signal lamps
B. To activate pedestrian crossing phases
Pedestrian push buttons allow pedestrians to request a walk signal
phase at intersections.
9. Which wiring method is commonly used for underground traffic signal
installations?
A. NM cable
B. Rigid metal conduit
C. Direct burial cable without protection
Traffic Signal SystemsExam Practice
Questions And Correct Answers
(Verified Answers) Plus Rationale 2026
Q&A| Instant Download Pdf
1. In a typical traffic signal system, which controller function is
responsible for determining the sequence and duration of signal
indications based on detected traffic demand and programmed timing
plans?
A. Load switch module
B. Conflict monitor unit
C. Signal controller unit
D. Flash transfer relay
C. Signal controller unit
The signal controller unit is the central processing device that
executes programmed timing plans and responds to detector inputs
to determine phase sequences and durations.
2. What is the primary purpose of a conflict monitor (malfunction
management unit) in a traffic signal cabinet?
A. To provide backup power during outages
B. To detect conflicting signal indications and place the system in flash
mode
C. To measure vehicle speed
, D. To synchronize signals across intersections
B. To detect conflicting signal indications and place the system in
flash mode
The conflict monitor ensures safety by detecting improper
simultaneous green signals and forcing the system into a safe
flashing mode.
3. Which type of detection system uses electromagnetic fields to sense
the presence of vehicles at an intersection?
A. Video detection
B. Infrared detection
C. Inductive loop detection
D. Microwave detection
C. Inductive loop detection
Inductive loop detectors are embedded in pavement and detect
vehicles through changes in electromagnetic fields caused by metal
objects.
4. What is the standard voltage level commonly used for traffic signal
indications in the United States?
A. 12 volts
B. 24 volts
C. 120 volts
D. 480 volts
C. 120 volts
Traffic signal indications typically operate at 120 volts AC, which is
standard for most signal equipment.
5. Which component converts low-voltage control signals from the
controller into high-voltage outputs for signal lamps?
A. Detector amplifier
B. Load switch
C. Conflict monitor
D. Flash relay
B. Load switch
, Load switches receive low-voltage signals and switch high-voltage
power to the signal lamps accordingly.
6. In a traffic signal system, what does “preemption” refer to?
A. Normal signal timing adjustment
B. Emergency vehicle override of normal signal operation
C. Pedestrian crossing activation
D. Backup power activation
B. Emergency vehicle override of normal signal operation
Preemption allows emergency vehicles to override normal signal
timing to receive a green indication for faster and safer passage.
7. Which device is typically used to provide battery backup during a
power outage at a signalized intersection?
A. Transformer
B. UPS system
C. Load center
D. Relay module
B. UPS system
Uninterruptible Power Supply (UPS) systems maintain signal
operation during power outages to ensure safety.
8. What is the purpose of a pedestrian push button in a traffic signal
system?
A. To control vehicle speed
B. To activate pedestrian crossing phases
C. To override the controller
D. To test signal lamps
B. To activate pedestrian crossing phases
Pedestrian push buttons allow pedestrians to request a walk signal
phase at intersections.
9. Which wiring method is commonly used for underground traffic signal
installations?
A. NM cable
B. Rigid metal conduit
C. Direct burial cable without protection
