NETTCP Traffic Management & Control Systems 3 — Questions and Answers
Question 1: What is the function of a ramp meter on a freeway?
- Measure the weight of trucks entering the freeway
- Regulate the rate at which vehicles enter the freeway to maintain mainline flow (Correct answer)
- Display speed limits to entering vehicles
- Count the number of vehicles exiting the freeway
Correct answer: Regulate the rate at which vehicles enter the freeway to maintain mainline flow
Ramp meters use signals to release vehicles one or two per green cycle, preventing demand surges that cause mainline breakdown.
Question 2: Which communication protocol is most commonly associated with traffic signal controllers in the United States for standardized communication?
- NTCIP (National Transportation Communications for ITS Protocol) (Correct answer)
- Modbus RTU
- HTTP/2
- CAN bus
Correct answer: NTCIP (National Transportation Communications for ITS Protocol)
NTCIP is the standard protocol suite allowing interoperability between traffic controllers, management systems, and field devices from different vendors.
Question 3: In a traffic signal system, 'preemption' is activated by:
- High pedestrian volumes at crosswalks
- Emergency vehicles, trains, or transit priority requests (Correct answer)
- A malfunctioning loop detector
- The time-of-day schedule in the controller
Correct answer: Emergency vehicles, trains, or transit priority requests
Preemption overrides normal signal operation to provide right-of-way to emergency vehicles, rail crossings, or high-priority transit.
Question 4: The Highway Capacity Manual (HCM) defines Level of Service (LOS) 'F' as:
- Free-flow conditions with minimal delay
- Stable flow near capacity with slight delays
- Oversaturated conditions with demand exceeding capacity and long delays (Correct answer)
- An intersection operating at exactly 100% capacity
Correct answer: Oversaturated conditions with demand exceeding capacity and long delays
LOS F represents a breakdown of flow where demand exceeds capacity, causing queues to grow and delays to become unacceptable.
Question 5: What does a flashing yellow arrow signal indicate to a left-turning driver?
- Left turns are prohibited
- Proceed without yielding to oncoming traffic
- Yield to oncoming traffic and pedestrians, then turn left when safe (Correct answer)
- Wait for a solid green arrow before turning
Correct answer: Yield to oncoming traffic and pedestrians, then turn left when safe
A flashing yellow arrow is a permissive left-turn indication requiring drivers to yield before turning, replacing the traditional circular green for this movement.
Question 6: In traffic engineering, 'v/c ratio' stands for:
- Vehicle-to-cyclist ratio
- Volume-to-capacity ratio (Correct answer)
- Velocity-to-count ratio
- Variable-to-constant ratio
Correct answer: Volume-to-capacity ratio
The volume-to-capacity ratio measures how close a roadway or intersection is to its operational limit; values near or above 1.0 indicate congestion.
Question 7: Which device is used to detect pedestrian presence at a crosswalk and extend the walk phase if needed?
- Inductive loop buried in the roadway
- Passive infrared or microwave pedestrian detector
- Video analytics camera focused on the signal head
- Push-button actuation with extended hold timer (Correct answer)
Correct answer: Push-button actuation with extended hold timer
Extended push-button actuators with hold timers detect when a pedestrian is still in the crosswalk and can extend the walk or pedestrian clearance interval.
NETTCP Traffic Management & Control Systems 3
What is the function of a ramp meter on a freeway?