Civil Engineering July 2021 | Vol 29 No 6

28 July 2021 Civil Engineering data, the imported layer thickness largely exceeds 500 mm. However, at km 214 the layer is only 300 mm thick. Laboratory test results for samples of the original pavement taken between 400 mm and 700 mm depth indicate CBR values which all exceed 30. Pavement visual condition A visual assessment of the pavement was carried out in April 2021 to identify any defects. The defects observed consist of small linear and alligator cracks in the outer wheel track. No significant rutting was observed. The defects are visually represented in Figure 5 by plotting of the estimated areas of distress. Road roughness (IRI) measurements In accordance with the contract specifica- tions, the road roughness must conform to the following requirements: Months IRI (mm/m) 60 3.0 2.5 2.0 1.5 1.0 0 50 40 30 20 10 0 Left IRI Right IRI Linear (Left IRI) Linear (Right IRI) Figure 6 Variation of average IRI with time 0.5 Location (SV, km) IRI (mm/m) 250 3.0 2.5 2.0 1.5 0.5 0 240 230 220 210 190 170 IRI-RHS IRI-LHS Figure 7 Variation of IRI values with road length (March 2021) 200 180 0.5 Average of 95th percentile deflection Yo (micrometer) 450 400 350 300 250 200 150 100 50 0 Q2 (2016/8) Q8 (2018/3) Q10 (2018/9) Q12 (2019/3) Q14 (2019/9) Q16 (2020/3) Q18 (2020/9) Q20 (2021/3) LHS RHS or both Measurement date Figure 8 Variation of average of 95 th percentile deflections with time