CME CME Transportation Engineering & Traffic Management 2 — Questions and Answers
Question 1: What does the 85th percentile speed represent in traffic engineering?
- The speed below which 85% of vehicles travel (Correct answer)
- The maximum posted speed limit
- The average speed of all vehicles
- The speed of the slowest 15% of drivers
Correct answer: The speed below which 85% of vehicles travel
The 85th percentile speed is the speed at or below which 85% of vehicles are traveling, commonly used to set posted speed limits.
Question 2: Which pavement design method is most widely used for flexible pavement in US municipal streets?
- AASHTO pavement design method (Correct answer)
- Westergaard rigid pavement method
- CBR method alone
- Benkelman beam deflection method
Correct answer: AASHTO pavement design method
The AASHTO pavement design method, based on the AASHO Road Test, is the most widely adopted approach for flexible pavement design in the US.
Question 3: What is a roundabout's primary safety advantage over a signalized intersection?
- Higher vehicle throughput at all times
- Elimination of high-speed right-angle and head-on conflicts (Correct answer)
- Lower construction cost
- Simpler pedestrian crossing design
Correct answer: Elimination of high-speed right-angle and head-on conflicts
Roundabouts eliminate the most severe crash types—right-angle and head-on collisions—by converting all conflicts to lower-speed merging movements.
Question 4: What is the function of a 'shy distance' in roadway cross-section design?
- Minimum distance between opposing travel lanes
- Lateral clearance buffer between travel lane edge and fixed objects that affects driver behavior (Correct answer)
- Required distance between driveways
- Setback for utilities from curb
Correct answer: Lateral clearance buffer between travel lane edge and fixed objects that affects driver behavior
Shy distance is the lateral clearance needed beyond a travel lane edge to prevent drivers from instinctively moving away from nearby fixed objects.
Question 5: Which federal act requires municipalities to consider Title VI equity impacts in transportation planning?
- Clean Water Act
- Civil Rights Act of 1964 (Title VI) (Correct answer)
- National Environmental Policy Act
- Safe, Accountable, Flexible, Efficient Transportation Equity Act
Correct answer: Civil Rights Act of 1964 (Title VI)
Title VI of the Civil Rights Act prohibits discrimination in federally funded programs, requiring transportation agencies to assess impacts on minority and low-income populations.
Question 6: What type of intersection control is typically recommended when peak-hour traffic volumes on the minor road are very low compared to the major road?
- Traffic signal
- Roundabout
- Two-way stop control (TWSC) (Correct answer)
- All-way stop control (AWSC)
Correct answer: Two-way stop control (TWSC)
Two-way stop control is appropriate when the major road has significantly higher volumes than the minor road, minimizing delay for the predominant traffic flow.
CME CME Transportation Engineering & Traffic Management 2
What does the 85th percentile speed represent in traffic engineering?