NETTCP Roadway Design & Maintenance 4 — Questions and Answers
Question 1: What type of retaining wall relies on the weight of the wall itself and retained soil for stability against overturning?
- Cantilever retaining wall
- Gravity retaining wall (Correct answer)
- Sheet pile wall
- Mechanically stabilized earth (MSE) wall
Correct answer: Gravity retaining wall
A gravity retaining wall uses its own mass and the weight of soil bearing on it to resist overturning and sliding forces without reinforcement.
Question 2: When designing roadway grades in New England, which factor is especially critical due to the regional climate?
- Hurricane wind load on signs
- Maximum grade steepness to prevent vehicle stalling in summer heat
- Grade and drainage design to prevent ice accumulation and black ice formation (Correct answer)
- Minimizing pavement reflectivity in winter months
Correct answer: Grade and drainage design to prevent ice accumulation and black ice formation
New England's freeze-thaw climate makes drainage and grade design critical to prevent water pooling that freezes into dangerous black ice conditions.
Question 3: A highway agency is evaluating a section of roadway for mill and overlay. What pavement condition primarily DISQUALIFIES a section from this treatment?
- Surface raveling in isolated areas
- Minor longitudinal cracking along the centerline
- Severe structural (alligator) cracking indicating base failure (Correct answer)
- Moderate transverse thermal cracking
Correct answer: Severe structural (alligator) cracking indicating base failure
Severe alligator cracking indicates base failure, meaning an overlay alone will not correct the structural deficiency and full-depth reclamation or reconstruction is needed.
Question 4: What is the purpose of a rumble strip installed on the centerline of a two-lane highway?
- To reduce speed on steep downhill grades
- To alert drowsy or inattentive drivers drifting across the centerline (Correct answer)
- To channel stormwater away from the pavement surface
- To delineate the passing zone for overtaking vehicles
Correct answer: To alert drowsy or inattentive drivers drifting across the centerline
Centerline rumble strips create audible and tactile warnings that alert drivers who drift across the centerline toward oncoming traffic.
Question 5: Which drainage structure is BEST suited to pass a high-volume stream beneath a roadway while allowing natural stream-bed migration and wildlife passage?
- Corrugated metal pipe culvert
- Concrete box culvert
- Open-bottom arch culvert or bridge (Correct answer)
- Perforated drain pipe
Correct answer: Open-bottom arch culvert or bridge
Open-bottom arches or bridges preserve the natural stream bottom, accommodating stream migration and wildlife passage that closed culverts prevent.
Question 6: In traffic calming design, which measure physically alters the roadway geometry to reduce vehicle speeds?
- Flashing speed limit signs
- Increased pavement marking frequency
- Speed table or raised crosswalk (Correct answer)
- High-visibility pavement markings only
Correct answer: Speed table or raised crosswalk
Speed tables and raised crosswalks are vertical deflection devices that physically compel drivers to reduce speed, unlike signage which relies on driver compliance.
Question 7: Under ADA requirements, what is the maximum running slope for a pedestrian access route within a transportation project?
- 1:10 (10%)
- 1:12 (8.3%)
- 1:20 (5%) (Correct answer)
- 1:50 (2%)
Correct answer: 1:20 (5%)
ADA standards require pedestrian access routes to have a maximum running slope of 1:20 (5%) unless designed as a ramp with handrails.
NETTCP Roadway Design & Maintenance 4
What type of retaining wall relies on the weight of the wall itself and retained soil for stability against overturning?