CTE Intelligent Transportation Systems (ITS) 2 — Questions and Answers
Question 1: What is 'travel time reliability' and why is it important in ITS performance measurement?
- The accuracy of DMS-posted travel time estimates vs. actual times
- The consistency of travel times from day to day, reflecting predictability of the transportation system (Correct answer)
- The percentage of time a corridor operates within its design capacity
- The statistical mean travel time across all routes in a network
Correct answer: The consistency of travel times from day to day, reflecting predictability of the transportation system
Travel time reliability measures day-to-day variability in travel times; a reliable facility has consistent travel times that travelers can plan around, which FHWA measures using the Planning Time Index (PTI) and Buffer Index (BI).
Question 2: What is 'ramp metering' and what transportation benefit does it provide?
- Metering parking in ramp garages adjacent to highways
- Controlling the rate at which vehicles enter a freeway on-ramp using traffic signals, to maintain mainline traffic flow (Correct answer)
- Charging variable tolls at freeway on-ramps based on congestion
- Restricting access to high-occupancy vehicle lanes at ramp terminals
Correct answer: Controlling the rate at which vehicles enter a freeway on-ramp using traffic signals, to maintain mainline traffic flow
Ramp metering uses a signal at freeway on-ramps to regulate vehicle entry rates, preventing traffic demand from exceeding freeway capacity and maintaining stable flow that prevents breakdown and reduces throughput loss.
Question 3: What does 'connected vehicle' technology refer to in the context of ITS?
- Vehicles with in-dash GPS navigation systems
- Vehicles equipped with wireless communication capabilities that exchange data with other vehicles, infrastructure, pedestrians, and the cloud (Correct answer)
- Vehicles linked to a fleet management system via cellular data
- Electric vehicles connected to the power grid for charging management
Correct answer: Vehicles equipped with wireless communication capabilities that exchange data with other vehicles, infrastructure, pedestrians, and the cloud
Connected vehicles use wireless communication (DSRC, C-V2X) to exchange data with other vehicles (V2V), infrastructure (V2I), pedestrians (V2P), and the network (V2N) to improve safety, mobility, and efficiency.
Question 4: In freeway traffic flow theory, what is the 'capacity drop' phenomenon?
- Reduction in freeway capacity due to geometric bottlenecks like lane reductions
- The observed drop in throughput when a freeway transitions from free flow to congested breakdown conditions (Correct answer)
- Capacity reduction caused by heavy vehicle grades on upgrades
- The decline in capacity as a facility ages without maintenance
Correct answer: The observed drop in throughput when a freeway transitions from free flow to congested breakdown conditions
Capacity drop refers to the empirically observed phenomenon where throughput at a freeway bottleneck during congested conditions is 5–15% lower than the pre-breakdown discharge rate, sustained as long as congestion persists.
Question 5: What is 'Wrong Way Driving (WWD) detection' and which ITS technology is most commonly used?
- Detection of vehicles traveling the wrong direction on one-way streets using parking enforcement cameras
- Detection of vehicles entering freeways in the wrong direction using radar, video, or thermal sensors at off-ramps, triggering alerts and DMS warnings (Correct answer)
- Automated enforcement of wrong-way turns at intersections using red-light cameras
- GPS tracking of erratic driver behavior for insurance telematics
Correct answer: Detection of vehicles entering freeways in the wrong direction using radar, video, or thermal sensors at off-ramps, triggering alerts and DMS warnings
Wrong way driving detection systems use radar, thermal cameras, or video analytics at freeway off-ramps and interchange areas to detect wrong-way vehicle movements and immediately activate DMS, signals, and alert responders.
Question 6: What is 'performance-based practical design' in the context of ITS project development?
- Designing ITS systems to meet minimum FTA performance standards
- Selecting ITS treatments and investments based on measured performance outcomes and data-driven needs rather than prescriptive standards (Correct answer)
- A bidding process requiring contractors to meet performance metrics post-construction
- A design methodology for autonomous vehicle testing facilities
Correct answer: Selecting ITS treatments and investments based on measured performance outcomes and data-driven needs rather than prescriptive standards
Performance-based practical design applies performance measurement to ITS investment decisions, selecting technologies and treatments that address identified deficiencies and deliver measured outcomes (reduced delay, improved reliability).
CTE Intelligent Transportation Systems (ITS) 2
What is 'travel time reliability' and why is it important in ITS performance measurement?