Network-level pavement deflection testing and structural evaluation

Structural evaluation provides valuable information about the expected beha vior of pavements and can be very useful at the network level of pavement m anagement for project prioritization purposes. However, due to the expense involved in data collection and analysis, structural capacity is usually no t determined at the network level. In Kansas, due to limited resources and the large size of the network (10 971 miles), annual network-level structur al data collection at the same rate (five to ten tests per mile) as the pro ject level is not realistic. This study was initiated to determine the samp le size (% mileage) at the network level as well as the test intervals and frequency that can be used as guides for network-level deflection testing a nd structural evaluation of pavements. Falling-weight deflectometer (FWD) data, collected on 571 km (357 miles) of non-interstate asphalt pavements of the Kansas Department of Transportatio n from 1993 to 1996, were used in the analysis. Three response variables we re studied: (1) normalized and temperature-corrected first sensor deflectio n, (2) backcalculated subgrade resilient modulus (M-r), and (3) effective p avement modulus (E-p). Statistical analysis of these variables showed that the FWD tests up to a three-year interval at the network level yield statis tically similar pavement responses and layer properties. At the network lev el, FWD tests on 20% mileage appear to be a valid statistical choice, and t hree tests per mile is the minimum test frequency required. An analysis pro cedure for assessing structural deterioration of pavements at the network l evel is also demonstrated.