NETTCP Traffic Management & Control Systems 5 — Questions and Answers
Question 1: A traffic engineer is reviewing detector occupancy data and notices values consistently above 80%. This most likely indicates:
- Detector malfunction due to a broken loop wire
- Highly congested or stopped traffic over the detector (Correct answer)
- Normal free-flow conditions at posted speed
- The detector is counting bicycles instead of vehicles
Correct answer: Highly congested or stopped traffic over the detector
High occupancy percentages mean vehicles are sitting over the detector for long periods, which is characteristic of stop-and-go or queued traffic.
Question 2: In signal timing design, the 'lost time' per phase accounts for:
- Time when the signal is in all-red only
- Start-up lost time and clearance lost time during which the intersection is not efficiently used (Correct answer)
- The time pedestrians spend waiting for the walk signal
- Gaps in traffic flow caused by heavy vehicles accelerating slowly
Correct answer: Start-up lost time and clearance lost time during which the intersection is not efficiently used
Lost time includes start-up delay as queued vehicles react and clearance time during the yellow and all-red, representing time the phase is not fully productive.
Question 3: Which technology allows a traffic management center to remotely adjust signal timing plans without a technician visiting the cabinet?
- CCTV surveillance camera
- Central signal control via fiber optic or wireless communication network (Correct answer)
- Passive loop detectors
- Variable speed limit signs
Correct answer: Central signal control via fiber optic or wireless communication network
A central signal control system communicates with field controllers over a network, enabling operators to push updated timing plans remotely.
Question 4: What is the primary reason for using a 'lag left-turn' phase instead of a 'lead left-turn' phase at a signalized intersection?
- Lag left turns always provide more green time
- A lag phase can reduce the overall cycle length and improve operations in certain traffic conditions (Correct answer)
- Lag phases are required by MUTCD at all intersections
- Lag left turns prevent pedestrian conflicts entirely
Correct answer: A lag phase can reduce the overall cycle length and improve operations in certain traffic conditions
A lag left-turn phase occurs after the opposing through movement, which can reduce cycle length and improve coordination under certain demand patterns.
Question 5: In New England states, winter maintenance operations often require coordination with traffic management because:
- Snow plows are prohibited from entering signalized intersections
- Plowing and anti-icing activities affect detector accuracy and require adjusted signal timing or worker protection plans (Correct answer)
- Traffic signals must be turned off during snowstorms
- Winter reduces traffic enough that signals revert to flashing mode automatically
Correct answer: Plowing and anti-icing activities affect detector accuracy and require adjusted signal timing or worker protection plans
Snow and ice can cover loop detectors and alter traffic patterns, requiring recalibration of detection and work zone signal plans to protect maintenance crews.
Question 6: A 'wrong-way driver' alert system on a freeway typically uses which combination of technologies?
- Speed radar and weigh-in-motion sensors
- Wrong-way detection cameras or sensors combined with DMS and motorist alert systems (Correct answer)
- Ramp meters and toll plaza cameras only
- Pedestrian push buttons and audible signals
Correct answer: Wrong-way detection cameras or sensors combined with DMS and motorist alert systems
Wrong-way detection systems use sensors or video at exit ramps, then activate DMS warnings and notify motorists and law enforcement in real time.
Question 7: The NETTCP program emphasizes that technicians performing work in or near travel lanes must comply with which foundational safety standard?
- OSHA 1926 Subpart R (Steel Erection)
- MUTCD Part 6 — Temporary Traffic Control (Work Zone) standards (Correct answer)
- EPA stormwater permit requirements
- FAA airspace regulations for drone operations
Correct answer: MUTCD Part 6 — Temporary Traffic Control (Work Zone) standards
MUTCD Part 6 establishes all requirements for temporary traffic control in work zones, including device placement, taper lengths, and worker protection.
NETTCP Traffic Management & Control Systems 5
A traffic engineer is reviewing detector occupancy data and notices values consistently above 80%.
This most likely indicates: