Evaluating the effect of incorporating network-level structural condition on pavement lifecycle cost

Abstract: The structural condition of road pavements significantly influences their performance and service life, making it essential to include in the selection and planning of future maintenance and rehabilitation treatments. However, due to network-level structural condition testing challenges, agencies often rely solely on surface-based condition data, resulting in inaccurate analysis and less-than-optimal treatment intervention plans on some sections of the network. Potential benefits of integrating network-level structural condition into agency pavement management processes have been demonstrated using one maintenance cycle. This paper evaluates the effect of incorporating network-level structural condition, obtained from the traffic speed deflectometer (TSD) data, on pavement lifecycle costs. Based on treatment categories and expected pavement life, a schedule of future maintenance and rehabilitation interventions required to maintain the pavement network in good condition was developed. A detailed pavement condition assessment was conducted to determine initial treatment recommendations for individual roadways based on functional condition only and combined functional and structural condition assessments. The FHWA’s life-cycle analysis methodology was used to estimate lifecycle costs based solely on functional treatment categories and combined functional and structural treatment categories on 2,000 lane miles of primary roads in Virginia, USA. Based on the functional assessment, 29.3%, 40.3%, 13.5%, 8.3%, and 8.6% were recommended for do nothing (DN), preventive maintenance (PM), corrective maintenance (CM), restorative maintenance (RM), and reconstruction (RC) treatment categories respectively. For the structural assessment, the treatment categories were 40.9%, 25.4%, 13.1%, 14.6%, and 6.0% for DN, PM, CM, RM, and RC respectively. Detailed examination of these findings revealed that individual road sections were not necessarily recommended for the same functional and structural treatment categories. Life-cycle cost analysis showed differences in costs among individual roads when structural treatment categories were considered compared to using solely the functional treatment categories. The differences varied based on the distribution of recommended treatment categories and analysis period, with most roads showing reductions in costs when structural treatment categories were considered. For the network, 20, 30, 35, and 50-year analysis periods using the net present value and equivalent uniform annual cost methods resulted in lifecycle cost reduction of 4.5%, 11.2%, 8.7%, and 5.8% respectively. Two detailed case studies—lifecycle costs decreased, and lifecycle costs decreased—were presented. While incorporating structural condition shows promising results regarding accurate treatment selection, future rehabilitation planning, and potential savings in pavement lifecycle costs, agencies need to conduct regular long-term repeated structural testing at the network level to develop more accurate structural deterioration models. To achieve this, systematic investigations to determine the appropriate interval between structural testing cycles are recommended.