MTO Roadway Design & Engineering 4 — Questions and Answers
Question 1: What is the purpose of a 'passing sight distance' standard on two-lane roads?
- To define the distance required to safely pass a slower vehicle before oncoming traffic arrives (Correct answer)
- To establish the spacing of passing lanes
- To determine the speed limit in passing zones
- To set the minimum length of no-passing zones
Correct answer: To define the distance required to safely pass a slower vehicle before oncoming traffic arrives
Passing sight distance is the minimum sight distance required to allow a driver to safely complete a passing maneuver before encountering oncoming traffic.
Question 2: Which road element is designed to slow vehicles by increasing discomfort at high speeds?
- Rumble strips (Correct answer)
- Speed tables
- Raised crosswalks
- Traffic circles
Correct answer: Rumble strips
Rumble strips create vibration and noise when driven over, alerting drivers that they are traveling too fast or drifting out of lane.
Question 3: What does 'ADT' stand for in traffic engineering?
- Average Daily Traffic (Correct answer)
- Annual Design Template
- Arterial Directional Travel
- Adjusted Distance Threshold
Correct answer: Average Daily Traffic
ADT (Average Daily Traffic) is the total traffic volume on a road segment during a given time period divided by the number of days in that period.
Question 4: In pavement design, what is the purpose of a 'base course'?
- To provide the wearing surface for vehicles
- To distribute loads from the surface to the subgrade (Correct answer)
- To waterproof the pavement structure
- To mark the boundary between concrete and asphalt sections
Correct answer: To distribute loads from the surface to the subgrade
The base course distributes traffic loads over a wider area before they reach the subgrade, preventing premature pavement failure.
Question 5: What is a 'diverging diamond interchange' (DDI) primarily designed to improve?
- Bicycle access to freeway ramps
- Left-turn movements to and from freeway ramps without signal phases (Correct answer)
- Pedestrian crossing safety at on-ramps
- Emergency vehicle preemption at interchanges
Correct answer: Left-turn movements to and from freeway ramps without signal phases
A DDI temporarily crosses traffic to the opposite side, eliminating left-turn conflicts and reducing the number of signal phases needed for freeway ramp movements.
Question 6: What does a higher 'K-value' indicate in vertical curve design?
- Steeper grades on both approaches
- A longer, more gradual vertical curve for a given algebraic grade difference (Correct answer)
- A sharper, shorter vertical curve
- Higher posted speed limits on the curve
Correct answer: A longer, more gradual vertical curve for a given algebraic grade difference
The K-value represents the length of vertical curve per percent of algebraic grade difference; a higher K-value means a flatter, longer curve.
Question 7: Which type of interchange is most commonly used on US Interstate highways?
- Diamond interchange (Correct answer)
- Trumpet interchange
- Cloverleaf interchange
- Single-point urban interchange
Correct answer: Diamond interchange
The diamond interchange is the most common interchange type on Interstate highways due to its simplicity, compact footprint, and cost-effectiveness.
MTO Roadway Design & Engineering 4
What is the purpose of a 'passing sight distance' standard on two-lane roads?