Analysis of implementation and maintenance costs of highways designed by empirical and mechanistic-empirical methods

Abstract

Decisions taken in the design phase and during the lifetime of pavements have the potential to impact their performance and rate of deterioration. Mention is made of the definition of the layer system (materials and thicknesses), which can be given by different design methods, and the choice of maintenance and rehabilitation (M&R) activities. In this context, it is clear that there is potential for combining pavement design strategies with Life Cycle Cost Analysis (LCCA) methods to help select adequate structure options of pavements and M&R activities that, combined, generate economically and technically more efficient pavements. This paper aims to evaluate the empirical and mechanistic-empirical methods most used in Brazil regarding their ability to design pavements efficiently when considering life cycle costs, in different traffic scenarios. The predicted percentage of cracked area (%AT) obtained by simulations with the MeDiNa software was adopted as a performance indicator. In order to maintain comparability between the evaluated scenarios, only one M&R strategy was adopted: milling-and-filling and total reconstruction of the surface asphalt layer. Such action is adopted whenever the expected %AT reaches 30% (design criterion adopted in MeDiNa). Different pavement alternatives demanded more or less repetitions of the proposed maintenance action. It was possible to conclude that, in scenarios with higher traffic, the use a more mechanistic design methods (in this case, the mechanistic-empirical method implemented in MeDiNa) tends to mitigate the volume of resources needed to deploy and maintain pavements throughout the cycle of life. In those scenarios, the surface layer value is very high and major interventions are costly and need to be avoided within the project horizon. As for pavements designed to serve less traffic, this logic is reversed, and the lower investment in construction can be justified to the point that under-designed pavements have lower life cycle costs.