NCDOT Traffic Engineering & Control 2 — Questions and Answers
Question 1: NCDOT uses level of service (LOS) grades A through F to evaluate intersection operations. Which LOS indicates the worst traffic conditions with excessive delays?
- LOS A
- LOS C
- LOS E
- LOS F (Correct answer)
Correct answer: LOS F
LOS F represents a breakdown of traffic flow with unacceptable delays, queuing, and congestion beyond intersection capacity.
Question 2: What does the term 'peak hour volume' represent in NCDOT traffic engineering studies?
- The highest 15-minute traffic count of the day multiplied by four
- The highest hourly traffic volume recorded during the study period (Correct answer)
- The average of the two busiest hours of the day
- The total daily volume divided by 24
Correct answer: The highest hourly traffic volume recorded during the study period
Peak hour volume is the highest traffic volume recorded in any single hour during the observation period, used to design for worst-case conditions.
Question 3: Which NCDOT document governs the design and placement of temporary traffic control (TTC) devices in construction work zones?
- NCDOT Roadway Standard Drawings
- NCDOT Standard Specifications for Roads and Structures
- NCDOT Work Zone Traffic Control Manual (Correct answer)
- NCDOT Pavement Design Manual
Correct answer: NCDOT Work Zone Traffic Control Manual
NCDOT's Work Zone Traffic Control Manual provides requirements for temporary traffic control devices, channelization, and safety measures in active construction zones.
Question 4: When designing a roundabout in North Carolina, which design element primarily controls vehicle speeds through the intersection?
- Sign placement and posted speed limit
- Number of lanes in the circulatory roadway
- Inscribed circle diameter and entry deflection geometry (Correct answer)
- Traffic signal phasing within the circle
Correct answer: Inscribed circle diameter and entry deflection geometry
Speed control in a roundabout is achieved through geometric deflection—specifically the inscribed circle diameter and the angle at which vehicles must turn to enter—forcing slower operating speeds.
Question 5: What is the standard NCDOT yellow change interval (yellow clearance time) purpose at a signalized intersection?
- To allow pedestrians to complete their crossing
- To warn drivers that the green phase is ending and they should prepare to stop (Correct answer)
- To provide all-red clearance for vehicles already in the intersection
- To extend green time for heavy turning movements
Correct answer: To warn drivers that the green phase is ending and they should prepare to stop
The yellow change interval warns drivers that the green phase is ending, providing time to decelerate and stop before the signal turns red.
Question 6: According to NCDOT driveway permit requirements, what is the primary concern when evaluating a proposed commercial driveway location?
- Driveway width and surface material
- Sight distance and potential conflict with traffic operations (Correct answer)
- Number of parking spaces in the development
- Landscaping requirements along the highway frontage
Correct answer: Sight distance and potential conflict with traffic operations
NCDOT driveway permits focus primarily on adequate sight distance and minimizing conflicts between driveway traffic and through highway operations.
Question 7: Which federal regulation requires NCDOT to prepare a Transportation Improvement Program (TIP) that programs projects receiving federal funding?
- Clean Air Act
- National Environmental Policy Act (NEPA)
- Moving Ahead for Progress in the 21st Century (MAP-21) and FAST Act (Correct answer)
- Americans with Disabilities Act (ADA)
Correct answer: Moving Ahead for Progress in the 21st Century (MAP-21) and FAST Act
Federal surface transportation laws including MAP-21 and the FAST Act require states to develop a financially constrained Transportation Improvement Program (TIP) for federally funded projects.
NCDOT Traffic Engineering & Control 2
NCDOT uses level of service (LOS) grades A through F to evaluate intersection operations.
Which LOS indicates the worst traffic conditions with excessive delays?