NETTCP Field Testing 4 — Questions and Answers
Question 1: A field technician performing a hand-held retroreflectometer test on pavement markings obtains a reading of 80 mcd/m²/lux. Most state DOTs require a minimum of 150 mcd/m²/lux for new markings. This result means:
- The markings pass since they are within 50% of the threshold
- The markings fail and should be reported for reapplication (Correct answer)
- Retroreflectivity is only measured at night so the result is invalid
- The reading should be averaged with three additional tests first
Correct answer: The markings fail and should be reported for reapplication
A reading of 80 mcd/m²/lux is well below the minimum 150 mcd/m²/lux threshold, constituting a clear failure requiring remediation.
Question 2: During a field embankment inspection, a technician observes that the contractor is placing fill lifts that appear to be 18 inches thick. Typical compaction specifications require maximum loose lift thickness of:
- 6 inches (150 mm)
- 8 inches (200 mm) (Correct answer)
- 12 inches (300 mm)
- 16 inches (400 mm)
Correct answer: 8 inches (200 mm)
Most NETTCP-region DOT specifications limit uncompacted lift thickness to 8 inches (200 mm) so compaction energy can reach the full layer depth.
Question 3: A field technician uses a digital thermometer to check asphalt mat temperature behind the paver and gets a reading of 215°F (102°C). The specification minimum for compaction start is 280°F (138°C). The correct action is:
- Begin compaction immediately before the mat cools further
- Notify the inspector and halt rolling until the cause is determined (Correct answer)
- Apply a light water mist to stabilize the surface temperature
- Increase roller speed to complete compaction before temperature drops more
Correct answer: Notify the inspector and halt rolling until the cause is determined
A mat temperature well below the compaction minimum indicates a delivery or laydown problem; the inspector must be notified before compaction proceeds.
Question 4: What test is used in the field to evaluate the bearing capacity of a subgrade using a rod and calibrated hammer system?
- Dynamic Cone Penetrometer (DCP) test (Correct answer)
- Standard Penetration Test (SPT)
- Clegg Impact Value test
- Plate Load Test
Correct answer: Dynamic Cone Penetrometer (DCP) test
The DCP uses a falling hammer to drive a cone into the soil; penetration rate per blow correlates with California Bearing Ratio (CBR) and subgrade strength.
Question 5: When conducting a field pipe joint infiltration test on a newly installed storm drainage system, the technician fills the pipe with water and monitors for leakage. What is primarily being assessed?
- Pipe wall permeability and material porosity
- Joint tightness and overall system watertightness (Correct answer)
- Flow velocity and hydraulic gradient
- Pipe wall thickness and structural integrity
Correct answer: Joint tightness and overall system watertightness
Infiltration or exfiltration tests check that pipe joints and connections are watertight so groundwater cannot enter and stormwater cannot leak out.
Question 6: A field technician is conducting a traffic count using a pneumatic tube counter. One tube is found cut and the counts are asymmetric. This will result in:
- Accurate volume counts but incorrect speed data
- Inflated vehicle counts on the intact tube channel
- Inaccurate axle counts and erroneous classification data (Correct answer)
- No data collected since the counter requires both tubes
Correct answer: Inaccurate axle counts and erroneous classification data
Pneumatic tube counters rely on both tubes to distinguish axle groupings for classification; a damaged tube corrupts axle and vehicle-type data.
Question 7: Which condition requires a field technician to STOP concrete placement operations on a bridge deck?
- Ambient temperature drops below 40°F (4°C) and is forecast to remain below 40°F for 24 hours (Correct answer)
- Wind speed exceeds 5 mph (8 km/h)
- Relative humidity rises above 70%
- Concrete temperature reaches 70°F (21°C)
Correct answer: Ambient temperature drops below 40°F (4°C) and is forecast to remain below 40°F for 24 hours
Cold weather concrete protection requirements typically mandate stopping placement or implementing approved cold-weather precautions when temperatures drop below 40°F (4°C).
NETTCP Field Testing 4
A field technician performing a hand-held retroreflectometer test on pavement markings obtains a reading of 80 mcd/m²/lux.
Most state DOTs require a minimum of 150 mcd/m²/lux for new markings.
This result means: