KDOT Traffic Signal & Signage Installation 3 — Questions and Answers
Question 1: A mast arm traffic signal pole is being installed. What factor primarily determines the required pole height?
- The speed limit of the roadway
- The number of lanes and required horizontal clearance for signal heads (Correct answer)
- The distance to the nearest signal cabinet
- The ambient light conditions at the intersection
Correct answer: The number of lanes and required horizontal clearance for signal heads
Mast arm height is determined by the number of lanes to span and the required vertical and horizontal clearances for mounted signal heads.
Question 2: What does 'intergreen' refer to in traffic signal terminology?
- A protected-permissive left turn display
- The yellow change interval plus the all-red clearance interval between phases (Correct answer)
- The minimum pedestrian walk time
- The period when all signals display green simultaneously
Correct answer: The yellow change interval plus the all-red clearance interval between phases
Intergreen is the combined yellow change and all-red clearance interval that separates conflicting traffic movements.
Question 3: When should retroreflective sign sheeting be inspected for replacement on KDOT facilities?
- Only when a complaint is filed
- Based on a scheduled maintenance program considering sheeting age and measured retroreflectivity (Correct answer)
- Every 10 years regardless of condition
- Only after storm damage
Correct answer: Based on a scheduled maintenance program considering sheeting age and measured retroreflectivity
MUTCD requires agencies to use either an assessment or management method to ensure sign retroreflectivity is maintained above minimum levels.
Question 4: A STOP sign must be installed at what height on an urban roadway with sidewalks?
- 5 feet minimum to bottom of sign
- 7 feet minimum to bottom of sign (Correct answer)
- 10 feet minimum to bottom of sign
- No minimum height requirement in urban areas
Correct answer: 7 feet minimum to bottom of sign
MUTCD requires a minimum mounting height of 7 feet from the bottom of the sign to the sidewalk level in pedestrian areas.
Question 5: What is the purpose of a detector loop in a traffic signal system?
- To count signal phases
- To detect vehicle presence or passage and send actuation data to the controller (Correct answer)
- To control pedestrian crossing timing
- To monitor cabinet temperature
Correct answer: To detect vehicle presence or passage and send actuation data to the controller
Inductive loop detectors sense the presence or passage of vehicles by detecting changes in inductance, sending this data to the signal controller for actuation.
Question 6: When installing overhead sign structures on KDOT highways, which specification primarily governs the structural design?
- AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals (Correct answer)
- ITE Manual of Traffic Signal Design
- KDOT Bridge Design Manual only
- OSHA 29 CFR 1926
Correct answer: AASHTO Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals
AASHTO's Standard Specifications for Structural Supports for Highway Signs, Luminaires, and Traffic Signals governs the structural design of overhead sign supports.
Question 7: What is a 'flashing beacon' used for in traffic control?
- To replace a full traffic signal at high-volume intersections
- To provide additional emphasis or warning at specific locations such as school zones or stop signs (Correct answer)
- To indicate construction work zones only
- To direct traffic during signal outages
Correct answer: To provide additional emphasis or warning at specific locations such as school zones or stop signs
Flashing beacons supplement other signs or signals to draw driver attention to important locations like school crossings or unexpected stop conditions.
KDOT Traffic Signal & Signage Installation 3
A mast arm traffic signal pole is being installed.
What factor primarily determines the required pole height?