KDOT Traffic Signal & Signage Installation 5 — Questions and Answers
Question 1: What is the minimum recommended luminance ratio between a traffic signal lens and its background during daylight?
- 2:1
- 5:1
- 10:1 (Correct answer)
- The signal itself must be visible — no specific ratio is set
Correct answer: 10:1
A luminance ratio of at least 10:1 between the lit signal lens and its background is recommended to ensure adequate daytime visibility.
Question 2: A KDOT inspector observes that a newly installed overhead sign is tilted 8 degrees from vertical. What is the appropriate action?
- Accept it if the sign is still readable
- Document and require correction before final acceptance (Correct answer)
- Only flag it if the tilt exceeds 15 degrees
- Approve it if the contractor provides a written waiver
Correct answer: Document and require correction before final acceptance
Signs must be installed plumb and level per specifications; deviations must be corrected before the inspector approves final acceptance.
Question 3: What is 'signal coordination' in the context of arterial traffic signal systems?
- Linking signal controllers so vehicles traveling at a designated speed can encounter progressive green lights (Correct answer)
- Synchronizing pedestrian countdown timers across all intersections
- Connecting all cabinets to a central power source
- Ensuring all signals on a corridor use identical phase plans
Correct answer: Linking signal controllers so vehicles traveling at a designated speed can encounter progressive green lights
Signal coordination times green phases on a corridor so vehicles traveling at the design speed experience a 'green wave,' improving arterial flow and reducing stops.
Question 4: Which MUTCD sign color combination is used for temporary traffic control (work zone) signs?
- Black on white
- Black on orange (Correct answer)
- White on red
- Black on yellow
Correct answer: Black on orange
Temporary traffic control signs in work zones use black text and symbols on an orange background, distinguishing them from permanent signs.
Question 5: When setting signal timing, what does 'minimum green' refer to?
- The maximum time the signal will display green before transitioning
- The shortest time the signal will remain green to allow stopped vehicles to begin moving (Correct answer)
- The all-red clearance time between phases
- The minimum pedestrian walk time required by ADA
Correct answer: The shortest time the signal will remain green to allow stopped vehicles to begin moving
Minimum green is the shortest duration the controller will allow a green indication before yielding to a competing call, ensuring queued vehicles can begin moving.
Question 6: What is the purpose of a 'conflict monitor' (also called a malfunction management unit) in a traffic signal cabinet?
- To log all signal phase changes for maintenance records
- To detect contradictory or unsafe signal indications and force the system to safe flash mode (Correct answer)
- To adjust signal timing based on real-time traffic data
- To communicate signal status to the traffic management center
Correct answer: To detect contradictory or unsafe signal indications and force the system to safe flash mode
The conflict monitor continuously checks for illegal simultaneous green indications or other faults and places the intersection in flash mode if detected.
Question 7: According to MUTCD, what is the correct lateral placement for a standard roadside sign post installed adjacent to a curbed urban street?
- Flush with the back of curb
- 1 to 2 feet behind the face of the curb
- 2 to 6 feet behind the face of the curb (Correct answer)
- Minimum 10 feet from the curb face
Correct answer: 2 to 6 feet behind the face of the curb
MUTCD recommends sign posts on curbed roadways be placed 2 to 6 feet behind the face of curb to provide clearance while keeping signs visible.
KDOT Traffic Signal & Signage Installation 5
What is the minimum recommended luminance ratio between a traffic signal lens and its background during daylight?