CPII Road and Pavement Inspection 4 — Questions and Answers
Question 1: The Falling Weight Deflectometer (FWD) primarily evaluates:
- Surface texture depth
- Structural capacity and layer moduli of the pavement system (Correct answer)
- Skid resistance of the pavement surface
- Pavement thickness by coring
Correct answer: Structural capacity and layer moduli of the pavement system
The FWD drops a weight to apply an impulse load and measures deflection basin data used to back-calculate layer moduli and remaining structural life.
Question 2: Which type of pavement marking retroreflectivity measurement device is most commonly used by state DOTs for compliance with MUTCD requirements?
- Retroreflectometer (Correct answer)
- Luminance meter
- Skid resistance tester
- IRI profiler
Correct answer: Retroreflectometer
Handheld or mobile retroreflectometers measure the retroreflectivity of pavement markings in mcd/m²/lux to ensure MUTCD minimum values are met.
Question 3: Under AASHTO Pavement Design, the Structural Number (SN) is calculated using:
- Layer thicknesses multiplied by their respective layer coefficients and drainage factors (Correct answer)
- CBR of the subgrade divided by axle load equivalencies
- IRI values weighted by traffic volume
- Deflection basin area from FWD testing
Correct answer: Layer thicknesses multiplied by their respective layer coefficients and drainage factors
SN = Σ(aᵢ × Dᵢ × mᵢ), where a is the layer coefficient, D is thickness, and m is the drainage coefficient for each pavement layer.
Question 4: Which drainage feature along a roadway is inspected specifically to ensure it conveys water away from the pavement edge without undermining the shoulder?
- Curb inlet
- Edge drain outlet (Correct answer)
- Median barrier
- Guardrail end treatment
Correct answer: Edge drain outlet
Edge drain outlets discharge subsurface water collected by edge drains; inspectors check for blockages, erosion at the outlet, and daylight pipe integrity.
Question 5: Polished aggregate in pavement surface is a concern primarily because it reduces:
- Pavement thickness
- Surface friction and skid resistance (Correct answer)
- Thermal stability of the binder
- Load-bearing capacity of the subgrade
Correct answer: Surface friction and skid resistance
Traffic wear rounds and polishes coarse aggregate particles, reducing micro-texture and skid resistance, increasing crash risk especially in wet conditions.
Question 6: When inspecting an unpaved gravel road, 'washboarding' is best corrected by:
- Adding a chip seal surface
- Motor grading to re-establish cross-slope and apply fresh aggregate (Correct answer)
- Installing edge drains along the road
- Placing geotextile fabric over the existing surface
Correct answer: Motor grading to re-establish cross-slope and apply fresh aggregate
Motor grading removes the rippled surface and restores proper cross-slope; adding fresh gravel may also be needed to rebuild lost aggregate.
Question 7: The primary reason inspectors check pavement cross-slope (superelevation runoff) is to ensure:
- Adequate structural strength under heavy trucks
- Proper drainage of surface water to prevent hydroplaning (Correct answer)
- Correct lane width for traffic capacity
- Compliance with horizontal curve radius standards
Correct answer: Proper drainage of surface water to prevent hydroplaning
Adequate cross-slope (typically 1.5–2% for tangent sections) ensures surface water drains off the pavement quickly, reducing hydroplaning risk.
CPII Road and Pavement Inspection 4
The Falling Weight Deflectometer (FWD) primarily evaluates: