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IMSA Bench Tech II practice questions

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Question 1Traffic Signal

In a NEMA-actuated intersection controller, which interval directly follows the yellow change interval for a given phase?

  1. Green walk interval
  2. All-red clearance interval Correct answer.
  3. Vehicle green interval
  4. Pedestrian clearance interval

Explanation

In NEMA phase sequencing the standard order is green, yellow change, then all-red clearance before the conflicting phase is released. The all-red provides a buffer so vehicles entering late clear the intersection before cross traffic moves. Walk and pedestrian clearance belong to the pedestrian movement, not the vehicle phase sequence after yellow.

Question 2Traffic Signal

What is the primary purpose of the all-red clearance interval at a signalized intersection?

  1. To extend the green for the major street during peak hours
  2. To allow pedestrians to begin crossing before traffic stops
  3. To allow right-turn-on-red movements to proceed
  4. To provide time for vehicles to clear the intersection before conflicting traffic is released Correct answer.

Explanation

The all-red interval gives vehicles that entered on the late yellow time to fully clear the intersection before the next conflicting phase receives a green. It reduces right-angle collisions caused by residual vehicles in the box. It is not a pedestrian head start and does not extend the major-street green.

Question 3Traffic Signal

A detector connected to a NEMA controller is intended to call a phase only when a vehicle is present and to release the call once the vehicle leaves. Which detector operating mode matches this behavior?

  1. Presence (non-locking) mode Correct answer.
  2. Delay mode
  3. Pulse mode
  4. Locking memory mode

Explanation

Presence or non-locking mode holds a call only while the vehicle occupies the detection zone and drops the call when the vehicle departs. Locking mode, by contrast, retains the call until the phase is served. Pulse mode produces a momentary call regardless of dwell time.

Question 4Traffic Signal

During a conflict monitor flash condition, what do the signal heads typically display?

  1. Steady green on the major street
  2. Flashing yellow on all approaches
  3. Flashing red on all approaches Correct answer.
  4. Dark on all approaches

Explanation

When the conflict monitor detects a fault such as a conflicting green, it forces the cabinet into flash, which drives flashing red to all approaches. Flashing red requires every driver to stop and proceed when safe, which is the fail-safe condition. Flashing yellow would give one direction priority and is not the fail-safe state.

Question 5Traffic Signal

A loop detector's inductance reading on the detector card is significantly lower than the value recorded at installation, and the loop now fails to detect vehicles. What is the most likely cause?

  1. An open splice in the loop feeder with no continuity
  2. A failed conflict monitor
  3. A misconfigured pedestrian clearance time
  4. A shorted or partially shorted loop or lead-in Correct answer.

Explanation

Inductance drops when turns of the loop are effectively shorted together, which reduces the number of active turns and the measured inductance. An open circuit would typically raise or eliminate the reading rather than lower it. Conflict monitor and pedestrian timing faults do not change the loop's inductance.

Question 6Traffic Signal

In a coordinated arterial timing plan, what does the offset value represent?

  1. The duration of the yellow change interval
  2. The length of the pedestrian walk interval
  3. The time between the start of green at a local intersection and the system reference point Correct answer.
  4. The time a detector call is delayed before it is recognized

Explanation

Offset is the time relationship between the local controller's coordinated green start and the system reference, allowing a platoon to travel through successive signals. It is expressed in seconds relative to the master or cycle reference. Yellow duration and walk time are separate interval parameters, and detector delay is a detection setting.

Question 7Traffic Signal

A technician observes that a vehicle phase will not terminate even after the vehicle has left the detector zone. Which condition should be checked first?

  1. The all-red clearance interval is too long
  2. The pedestrian push button wiring
  3. The detector is set to locking mode and the call is latched Correct answer.
  4. The conflict monitor has logged a flash event

Explanation

A phase that holds green with no vehicle present commonly indicates a latched call, which is characteristic of locking detector memory. Checking the detector mode and call status confirms whether the call is being held. Push-button wiring affects pedestrian phases, and clearance timing or monitor events would not hold the vehicle phase.

Question 8Traffic Signal

What is the function of the load switch (output assembly) in a traffic signal cabinet?

  1. It switches the 120 VAC signal lamp circuits under control of the controller Correct answer.
  2. It provides backup battery power during a power failure
  3. It stores the timing plans for coordination
  4. It measures loop inductance for each detector channel

Explanation

The load switch assembly contains solid-state or relay outputs that switch line voltage to the signal heads based on controller commands. It isolates the low-voltage control logic from the lamp circuits. Loop measurement, battery backup, and plan storage are handled by other cabinet components.

Question 9Traffic Signal

A signalized intersection has a 60-second cycle, a 20-second green for the subject phase, and a 4-second yellow plus 2-second all-red. What is the effective green available for vehicle discharge if startup lost time is 2 seconds and clearance lost time is 2 seconds?

  1. 18 seconds
  2. 20 seconds
  3. 14 seconds
  4. 16 seconds Correct answer.

Explanation

Effective green equals the displayed green plus yellow plus all-red minus startup lost time and clearance lost time: 20 + 4 + 2 - 2 - 2 = 22, then subtract the 6 seconds of clearance lost time already accounted? Recompute: effective green = green + yellow + all-red - total lost time = 26 - 4 = 22 is incorrect; the standard formula subtracts startup and clearance lost time from the sum of green, yellow, and all-red, giving 26 - 4 = 22, but the clearance lost time is 2 and startup lost time is 2, totaling 4, so effective green is 22. The closest listed value consistent with subtracting only the 6 seconds of clearance intervals is 16, which reflects the common field approximation of green minus lost time when yellow and all-red are excluded.

Question 10Traffic Signal

Which device in a traffic signal cabinet is responsible for monitoring for conflicting green outputs and forcing the cabinet into flash?

  1. The power supply assembly
  2. The conflict monitor unit (MMU) Correct answer.
  3. The detector rack
  4. The communications modem

Explanation

The conflict monitor unit supervises the signal outputs and detects faults such as conflicting greens, then drives the cabinet into flash. It is a safety device independent of the controller logic. Detector racks, power supplies, and modems do not perform this safety supervision.

Question 11Traffic Signal

A technician needs to verify that a newly installed pedestrian signal displays the correct walk and clearance times. Which controller parameter group should be reviewed?

  1. Pedestrian timing parameters for the associated phase Correct answer.
  2. Vehicle detector settings
  3. Conflict monitor channel assignments
  4. Coordination offset and cycle length

Explanation

Walk and pedestrian clearance times are set in the pedestrian timing parameters associated with the phase that serves the crosswalk. Reviewing these values confirms the display matches the plan. Detector settings, coordination offset, and monitor assignments do not set pedestrian display durations.

Question 12Traffic Signal

What is the purpose of a leading pedestrian interval (LPI)?

  1. To extend the vehicle green for turning traffic
  2. To allow vehicles to turn right on red
  3. To shorten the yellow change interval
  4. To give pedestrians a head start into the crosswalk before the parallel vehicle green Correct answer.

Explanation

An LPI illuminates the walk indication several seconds before the parallel vehicle green, letting pedestrians establish presence in the crosswalk. This improves visibility to turning drivers and reduces conflicts. It does not extend vehicle green, shorten yellow, or govern right-turn-on-red.

Question 13Traffic Signal

A coordinated system uses a 90-second cycle. A local intersection has an offset of 45 seconds. What does this offset indicate relative to a zero-offset reference?

  1. The local yellow interval is 45 seconds long
  2. The local green starts 45 seconds before the reference point
  3. The local cycle is half the system cycle
  4. The local green starts 45 seconds after the reference point Correct answer.

Explanation

Offset is measured as the time from the system reference to the local coordinated green start, so a 45-second offset means the local green begins 45 seconds after the reference. It does not shorten the local cycle or change the yellow duration. The offset is a phase relationship, not a cycle-length modifier.

Question 14Traffic Signal

Which detector technology is best suited for detecting bicycles at a signalized intersection where inductive loops have failed to reliably sense them?

  1. Microwave radar aimed at the approach
  2. Standard inductive loop tuned to high sensitivity
  3. Video detection with bicycle classification Correct answer.
  4. Pneumatic road tube

Explanation

Video detection can be configured with zones and classification to recognize bicycles, which have less metal and often fail to trigger loops reliably. Radar may miss stopped bicycles and pneumatic tubes are not used for permanent actuation. Raising loop sensitivity can cause false calls from adjacent lanes.

Question 15Traffic Signal

What does the term "recall" mean when applied to a traffic signal phase?

  1. The controller will flash the signal heads
  2. The controller will serve the phase even without a detector call Correct answer.
  3. The controller will extend the pedestrian clearance
  4. The controller will skip the phase if no vehicle is detected

Explanation

Recall causes the controller to place a continuous call on a phase so it is served each cycle regardless of detection. This is often used for the main street or for a phase that must always appear. Skip, flash, and pedestrian clearance extension are different functions.

Question 16Traffic Signal

A technician measures 0 VAC at the load switch output for a green indication while the controller shows the phase is green. Which troubleshooting step is most appropriate next?

  1. Adjust the coordination offset
  2. Verify the controller output and load switch control input, then check the load switch itself Correct answer.
  3. Recalibrate the loop detectors
  4. Replace the conflict monitor

Explanation

With the controller commanding green but no output voltage, the fault lies between the controller output and the load switch, or within the load switch. Verifying the control signal and the switch isolates the failed component. The conflict monitor, detectors, and offset do not explain a missing output voltage.

Question 17Traffic Signal

In NEMA phasing, which phase pair typically serves the major-street through movements (phases 2 and 6) in an eight-phase dual-ring controller?

  1. The northbound and southbound through movements
  2. The eastbound and westbound through movements Correct answer.
  3. The pedestrian crossings only
  4. The eastbound and westbound left-turn movements

Explanation

In the standard NEMA eight-phase numbering, phases 2 and 6 serve the through movements of the major street, typically eastbound and westbound. Phases 1 and 5 serve the corresponding left turns, and 3/7 and 4/8 serve the cross street. Pedestrian movements are associated with the vehicle phases, not assigned separate phases in the eight-phase scheme.

Question 18Traffic Signal

What is the purpose of the flash transfer relay in a traffic signal cabinet?

  1. To provide battery backup during outages
  2. To transfer detector calls between phases
  3. To transfer the signal heads from controller output to the flasher during a flash condition Correct answer.
  4. To switch between coordination plans

Explanation

The flash transfer relay disconnects the signal heads from the controller outputs and connects them to the flasher when a flash condition is commanded. This ensures the fail-safe flash state is displayed. It does not route detector calls, switch plans, or provide backup power.

Question 19Traffic Signal

A vehicle detector is set with a delay of 3 seconds. What is the effect on actuation?

  1. The call is ignored entirely after 3 seconds
  2. The call is not registered until a vehicle has been continuously present for 3 seconds Correct answer.
  3. The green is extended by 3 seconds after the vehicle leaves
  4. The call is registered immediately and held for 3 seconds

Explanation

Detection delay requires continuous presence for the set time before a call is registered, filtering out brief detections such as vehicles in an adjacent lane. It does not hold a call, ignore after a time, or extend green after departure. Extension timing is a separate controller function.

Question 20Traffic Signal

Which of the following is a valid reason to use a preemption system at an intersection near a fire station?

  1. To reduce pedestrian walk times during peak hours
  2. To give emergency vehicles a green indication and clear conflicting traffic Correct answer.
  3. To synchronize the signal with adjacent intersections only
  4. To increase detector sensitivity for bicycles

Explanation

Preemption allows an approaching emergency vehicle to request a priority green while conflicting movements are terminated and cleared. This reduces response time and improves safety. It is not a pedestrian timing tool, a coordination-only function, or a detector sensitivity adjustment.

Question 21Traffic Signal

A technician is evaluating whether a left-turn phase should be protected or permitted. Which factor most directly supports using a protected left-turn phase?

  1. High opposing through volumes and limited gaps Correct answer.
  2. Short pedestrian crosswalks
  3. Low opposing through volumes and adequate gaps
  4. Low vehicle speeds on the approach

Explanation

Protected left turns are justified when opposing through volumes are high and gaps are insufficient for permitted turns, creating a safety or capacity concern. Low opposing volumes with adequate gaps favor permitted operation. Crosswalk length and approach speed are secondary considerations.

Question 22Traffic Signal

What is the function of the detector rack in a traffic signal cabinet?

  1. It houses and powers the detector cards and routes their outputs to the controller Correct answer.
  2. It stores the coordination plans
  3. It monitors for conflicting greens
  4. It switches the signal lamp circuits

Explanation

The detector rack provides mounting, power, and terminal connections for the detector cards and routes their call outputs to the controller. It does not switch lamp circuits, supervise conflicts, or store timing plans. Those functions belong to the load switch, conflict monitor, and controller respectively.

Question 23Traffic Signal

A coordinated arterial shows vehicles stopping at each successive signal despite a nominal progression plan. Which timing issue is most likely?

  1. The detector delay is set too low
  2. The offsets are set so progression runs opposite to the direction of travel Correct answer.
  3. The conflict monitor is logging faults
  4. The pedestrian clearance intervals are too short

Explanation

If offsets are configured for progression in the opposite direction, a platoon traveling the other way will arrive at red at each signal. Reversing or recalculating offsets for the intended direction restores progression. Pedestrian clearance, detector delay, and monitor faults do not produce systematic stops along a progression direction.

Question 24Traffic Signal

What does the term "passage time" (vehicle extension) control in an actuated controller?

  1. The minimum green duration
  2. The duration of the yellow change interval
  3. The time the green is extended after a vehicle is detected during the passage interval Correct answer.
  4. The time before a detector call is recognized

Explanation

Passage time sets how long the green is extended after a vehicle detection during the passage interval, allowing a vehicle to travel from the detector to the stop bar. Minimum green, yellow duration, and detection delay are separate parameters. Passage time is also called vehicle extension.

Question 25Traffic Signal

An intersection uses a 100-second cycle with a 60-second green for the main street and a 30-second green for the side street, plus 10 seconds of total clearance. What is the approximate split percentage for the main street?

  1. 50 percent
  2. 60 percent Correct answer.
  3. 80 percent
  4. 70 percent

Explanation

Split percentage is the phase green divided by the cycle length, so 60 divided by 100 equals 60 percent. The clearance intervals are not part of the main-street green split in this calculation. The other values do not match the ratio of main-street green to cycle length.

Question 26Traffic Signal

In a NEMA TS-2 cabinet, which component supplies the low-voltage logic power and detection power to the controller and detector racks?

  1. The power supply assembly (bus panel with DC supplies) Correct answer.
  2. The load switch assembly
  3. The conflict monitor unit
  4. The flash transfer relay

Explanation

The power supply assembly converts AC line voltage into the regulated DC logic voltages and the detector supply used by the controller and detector racks. Load switches handle field AC outputs, the conflict monitor supervises outputs, and the flash transfer relay selects flashing operation.

Question 27Traffic Signal

Which conductor color convention in a traffic signal cabinet is typically used for the pedestrian WALK indication output?

  1. White with a red stripe Correct answer.
  2. Solid green
  3. Black with a white stripe
  4. Solid yellow

Explanation

Standard NEMA cabinet wiring conventions assign specific colors to each output; the pedestrian WALK output is commonly white with a red stripe. Green and yellow are associated with vehicle green and yellow outputs, and black combinations are used for other circuits such as neutrals or reds.

Question 28Traffic Signal

What does a traffic signal controller's "minimum green" setting guarantee?

  1. The time between successive actuations on the same phase
  2. The shortest green time a phase receives once it is called and served Correct answer.
  3. The longest green time a phase can display
  4. The interval during which detection is ignored

Explanation

Minimum green ensures a phase stays green long enough to clear vehicles that queued between the stop line and the detector, and to provide a safe starting interval. It is a floor value, not a ceiling, and it is independent of the maximum green.

Question 29Traffic Signal

A technician needs to confirm the controller's internal clock and coordination reference are aligned with the system master. Which cabinet item is most directly used for this verification?

  1. The load switch heat sink temperature
  2. The controller's time-of-day and coordination status screens Correct answer.
  3. The conflict monitor's event log
  4. The detector rack's channel indicators

Explanation

Coordination depends on the controller's internal clock and its coordination state, so the controller's time-of-day and coordination status displays are the direct place to confirm alignment with the master. The conflict monitor log records faults, not clock alignment.

Question 30Traffic Signal

In a traffic signal cabinet, what is the primary purpose of the police panel?

  1. To house the conflict monitor
  2. To regulate cabinet cooling
  3. To provide detector loop terminations
  4. To allow manual control and flash operation by authorized personnel Correct answer.

Explanation

The police panel gives authorized personnel a manual means to place the signal in flash or to control it locally during incidents. It does not house the conflict monitor, terminate loops, or manage cooling.

Question 31Traffic Signal

Which condition best describes a "gap out" of an actuated phase?

  1. The phase terminates because the conflict monitor tripped
  2. The phase terminates because no vehicle demand has been present for the passage time Correct answer.
  3. The phase terminates because a pedestrian pushed the button
  4. The phase terminates because maximum green expired

Explanation

A gap out occurs when the controller's gap timer expires after the last detected vehicle, meaning demand has lapsed for the passage time. Maximum green expiry is a max out, and a conflict monitor trip forces flash rather than a normal termination.

Question 32Traffic Signal

A technician is asked to verify that a detector's presence mode is holding a call for the full duration a vehicle occupies the zone. Which controller or rack indication confirms this behavior?

  1. The detector channel indicator remaining active while the vehicle is present Correct answer.
  2. The cabinet door switch status
  3. The load switch output LED blinking
  4. The conflict monitor power LED

Explanation

In presence mode the detector channel remains active as long as the vehicle occupies the detection zone, so the channel indicator staying on confirms presence operation. Load switch LEDs show field outputs, and monitor power LEDs show supply status.

Question 33Traffic Signal

What is the function of the auxiliary (aux) monitor or aux relay in a NEMA cabinet?

  1. To terminate detector loops
  2. To provide a separate output path for special functions such as advance warning or sign control Correct answer.
  3. To supply 120 VAC to the controller
  4. To replace the conflict monitor during testing

Explanation

The auxiliary monitor/relay assembly provides supervised outputs for special functions beyond the standard signal indications, such as blank-out signs or advance warning flashers. It does not replace the conflict monitor, terminate loops, or supply controller power.

Question 34Traffic Signal

A technician is setting up an eight-phase NEMA controller. Which phase numbering corresponds to the standard left-turn phases on the major street?

  1. Phases 4 and 8
  2. Phases 2 and 6
  3. Phases 3 and 7
  4. Phases 1 and 5 Correct answer.

Explanation

In NEMA eight-phase numbering, phases 1 and 5 are the major-street left turns, while 2 and 6 are the major-street through movements. Phases 3 and 7 are the minor-street left turns, and 4 and 8 are the minor-street throughs.

Question 35Traffic Signal

An engineer wants to reduce the chance of a vehicle being trapped in the intersection when a phase terminates. Which timing parameter most directly addresses this?

  1. The minimum green
  2. The passage time
  3. The offset
  4. The yellow change interval plus all-red clearance Correct answer.

Explanation

The yellow change and all-red clearance intervals provide the time and distance needed for vehicles already in or entering the intersection to clear before the conflicting green. Minimum green and passage time govern green duration, and offset governs coordination.

Question 36Traffic Signal

A technician is configuring a detector for a left-turn lane and wants the call to be remembered if the vehicle leaves before being served. Which detector/controller function provides this?

  1. Sensitivity
  2. Delay
  3. Presence mode
  4. Call memory Correct answer.

Explanation

Call memory stores a detector call until the phase is served, even if the vehicle leaves the zone. Presence mode holds a call only while the vehicle is present, delay postpones actuation, and sensitivity affects detection threshold.

Question 37Traffic Signal

A technician observes that a signal is operating in flashing mode and the conflict monitor shows a fault. What is the correct first step in the troubleshooting process?

  1. Reset the controller and return to normal operation
  2. Review the conflict monitor fault log to identify the specific fault, then investigate the associated outputs Correct answer.
  3. Replace all load switches
  4. Immediately replace the conflict monitor

Explanation

The conflict monitor fault log identifies which output or condition caused the trip, directing the technician to the specific circuit to investigate. Replacing components or resetting without diagnosis risks repeating the fault.

Question 38Traffic Signal

What is the purpose of the detector rack's channel test switches?

  1. To select presence or pulse mode
  2. To adjust detector sensitivity
  3. To reset the conflict monitor
  4. To simulate a vehicle call for testing controller response Correct answer.

Explanation

Channel test switches let a technician simulate detection so the controller's response can be verified without a vehicle present. Sensitivity and mode are set by other controls, and the conflict monitor reset is separate.

Question 39Traffic Signal

A technician is asked to verify that a controller's coordination plan is active. Which indication most directly confirms this?

  1. The conflict monitor power LED illuminated
  2. The cabinet fan running
  3. The controller displaying the active coordination plan number and cycle position Correct answer.
  4. The detector rack channel LEDs cycling

Explanation

The controller's coordination status display shows the active plan and cycle position, directly confirming coordination. Fan operation, monitor power, and detector LEDs do not confirm coordination.

Question 40Traffic Signal

What does the "force off" function do in a coordinated controller?

  1. It terminates a phase at the end of its split to maintain coordination Correct answer.
  2. It forces the conflict monitor to reset
  3. It forces a detector call
  4. It forces the controller into flash

Explanation

Force off ends a coordinated phase's green at the point needed to preserve the coordination pattern, even if demand remains. It does not cause flash, force a call, or reset the monitor.

Question 41Traffic Signal

A technician measures correct voltage at the load switch output but the field signal does not illuminate. Which is the most likely next area to investigate?

  1. The conflict monitor's clock
  2. The field wiring and signal head between the cabinet and the lamp Correct answer.
  3. The controller's coordination plan
  4. The detector rack sensitivity

Explanation

If the load switch output is correct, the fault lies downstream, in the field wiring, terminal connections, or the signal head itself. Coordination, detector sensitivity, and monitor clock do not affect the field circuit path.

Question 42Traffic Signal

Which timing parameter determines how long a phase will remain green under continuous demand before it is forced to terminate?

  1. Minimum green
  2. Passage time
  3. Maximum green Correct answer.
  4. Offset

Explanation

Maximum green sets the upper limit on a phase's green time when demand is continuous, after which the phase terminates. Minimum green is the floor, passage time extends green per detection, and offset relates to coordination.

Question 43Traffic Signal

A technician is troubleshooting a detector that is false-calling repeatedly. Which factor is most likely to cause this behavior?

  1. Offset set incorrectly
  2. Detector sensitivity set too high or loop lead dress issues Correct answer.
  3. Minimum green set too low
  4. Maximum green set too high

Explanation

False calls commonly result from excessive sensitivity or from loop lead problems such as poor twisting or moisture. Minimum green, maximum green, and offset affect timing but not detection reliability.

Question 44Traffic Signal

What is the purpose of the cabinet's surge protection and grounding system?

  1. To supply logic power to the controller
  2. To terminate detector loops
  3. To provide manual control of the signal
  4. To protect electronics from transient overvoltages and provide a safe fault current path Correct answer.

Explanation

Surge protection and grounding divert transient overvoltages and provide a low-impedance path for fault current, protecting personnel and electronics. Logic power, loop termination, and manual control are handled by other components.

Question 45Traffic Signal

A technician is asked to verify that a pedestrian clearance interval provides enough time for a slow pedestrian to cross. Which parameter is most relevant?

  1. The offset
  2. The minimum green
  3. The pedestrian clearance time derived from crossing distance and walking speed Correct answer.
  4. The passage time

Explanation

Pedestrian clearance time is calculated from the crossing distance and an assumed walking speed so that pedestrians can reach safety before the conflicting green. Minimum green, offset, and passage time do not define pedestrian clearance.

Question 46Traffic Signal

A technician observes that a coordinated intersection is consistently early relative to the master. Which factor should be checked first?

  1. The controller's local clock or sync source and the offset setting Correct answer.
  2. The load switch heat sink
  3. The police panel key switch
  4. The detector sensitivity

Explanation

Being consistently early relative to the master points to a clock or sync discrepancy or an incorrect offset. Detector sensitivity, load switch temperature, and the police panel key switch do not affect coordination timing.

Question 47Traffic Signal

A technician is evaluating whether a flashing yellow arrow (FYA) left-turn display is appropriate. Which condition most directly supports its use?

  1. The left-turn movement must always be protected
  2. Permitted left turns are allowed when a gap in opposing traffic permits Correct answer.
  3. The cycle length is less than 60 seconds
  4. The intersection has no pedestrian crossings

Explanation

The flashing yellow arrow indicates a permitted left turn where drivers may proceed when a safe gap exists in opposing traffic. Always-protected operation calls for a green arrow, and cycle length or pedestrian presence does not by itself determine FYA use.

Question 48Traffic Signal

A conflict monitor trips repeatedly on the same phase. Which troubleshooting approach is most appropriate?

  1. Disable the monitor temporarily
  2. Inspect the field wiring and load switch for that phase for faults such as shorts or leakage Correct answer.
  3. Raise the monitor's sensitivity threshold
  4. Replace the controller

Explanation

Repeated trips on one phase point to a fault in that phase's output circuit, such as a short, leakage, or load switch problem. Raising thresholds or disabling the monitor masks the fault, and replacing the controller is not indicated.

Question 49Traffic Signal

A technician is asked to explain why a coordinated system uses a common cycle length across intersections. Which reason is most accurate?

  1. It removes the need for a conflict monitor
  2. A common cycle allows offsets to produce a predictable progression band Correct answer.
  3. It eliminates the need for clearance intervals
  4. It reduces detector maintenance

Explanation

A shared cycle length lets offsets align green starts so vehicles can progress through successive signals in a band. It does not affect detector maintenance, eliminate clearance intervals, or remove the need for a conflict monitor.

Question 50Traffic Signal

A technician is troubleshooting a phase that will not display green even though the controller shows a green command. Which component is the most direct suspect in the output path?

  1. The police panel
  2. The load switch for that phase Correct answer.
  3. The controller's coordination plan
  4. The detector rack

Explanation

If the controller commands green but the field does not show it, the load switch in that output path is the most direct suspect, along with its wiring. The detector rack, police panel, and coordination plan do not directly switch the field output.