NETTCP Roadway Design & Maintenance 2 — Questions and Answers
Question 1: What is the primary purpose of a superelevation transition in horizontal curve design?
- To increase the posted speed limit
- To gradually rotate the roadway cross-section from normal crown to full superelevation (Correct answer)
- To widen the lane through the curve
- To reduce the curve radius
Correct answer: To gradually rotate the roadway cross-section from normal crown to full superelevation
Superelevation transition gradually rotates the roadway cross-section to counteract centrifugal forces on vehicles navigating horizontal curves.
Question 2: Which AASHTO design element determines the minimum stopping sight distance on a vertical curve?
- The curve's ADT
- The lane width and shoulder width
- The design speed and driver eye/object height (Correct answer)
- The pavement friction coefficient only
Correct answer: The design speed and driver eye/object height
AASHTO stopping sight distance is based on design speed combined with standard driver eye height (3.5 ft) and object height (2.0 ft) assumptions.
Question 3: A roadway segment has an existing subgrade CBR of 4. Which corrective action is MOST appropriate before paving?
- Apply a chip seal surface treatment
- Stabilize the subgrade with lime or cement (Correct answer)
- Reduce the pavement design life
- Increase the asphalt surface course thickness only
Correct answer: Stabilize the subgrade with lime or cement
A low CBR indicates weak subgrade support, and stabilization with lime or cement improves its load-bearing capacity before paving.
Question 4: Under MUTCD standards, what color is used for temporary traffic control (work zone) signs?
- Green on white
- Black on yellow
- Black on orange (Correct answer)
- White on red
Correct answer: Black on orange
The MUTCD specifies black lettering on an orange background for all temporary traffic control signs in work zones.
Question 5: What is the function of a longitudinal drainage pipe installed parallel to the roadway?
- To carry stormwater laterally across the road
- To collect and convey subsurface or surface runoff along the roadway corridor (Correct answer)
- To irrigate roadside vegetation
- To support the edge of pavement structurally
Correct answer: To collect and convey subsurface or surface runoff along the roadway corridor
Longitudinal drain pipes collect runoff from ditches or subsurface layers and convey it along the road corridor to an outfall.
Question 6: Which pavement distress type is characterized by a series of closely spaced transverse cracks resembling an alligator hide?
- Rutting
- Reflection cracking
- Fatigue (alligator) cracking (Correct answer)
- Thermal cracking
Correct answer: Fatigue (alligator) cracking
Fatigue cracking, also called alligator cracking, results from repeated traffic loading that exceeds the pavement's structural capacity.
Question 7: What does a k-value represent in the design of a vertical curve?
- The skid resistance coefficient of the pavement
- The rate of change of grade per unit length of curve (Correct answer)
- The number of lanes on the roadway
- The load equivalency factor for heavy trucks
Correct answer: The rate of change of grade per unit length of curve
The K-value is the length of vertical curve (in feet) required per one percent change in grade, used to ensure adequate sight distance.
NETTCP Roadway Design & Maintenance 2
What is the primary purpose of a superelevation transition in horizontal curve design?