Contribuição para a previsão empírico-mecanicista da irregularidade longitudinal e seus desdobramentos econômicos em pavimentos asfálticos

Abstract

The guarantee of ride quality conditions with safety and comfort is one of the main objectives during a road structure design. A road functional behavior is evaluated quantitatively by indexes that determine, among other parameters, the surface roughness. Thus, inserted in the current scenario of changes instituted in pavement design methodology in Brazil, the present study seeks to contribute to the roughness prediction, represented by the International Roughness Index (IRI), through the elaboration of functional models from national pavements. Through monitoring actions on sites located in Santa Maria/RS and Rio de Janeiro/RJ, it was aimed to evaluate the evolution of IRI, correlating this indicator with other parameters measured in the field. After verifying which independent variables adequately compose an empirical prediction model, the mechanistic methodology was connect to the work scope, by predicting the IRI evolution using the average damage, calculated computationally with AEMC (Multiple Layers Elastic Analysis) and the LVECD (Layered Viscoelastic Analysis for Critical Distresses) software. The procedure allowed the elaboration of mechanistic-empirical prediction equations, based on observed initial IRI, obtained just after pavement construction, pavement age and the computationally calculated average damage. The linear regression model was the most satisfactory pattern for roughness evolution, with coefficients of determination (R²) value of 0.78 and 0.79, respectively, for the models using average damage determined by AEMC and LVECD. A validation of these models were also attempted with other Brazilian National MEPDG project sites and compared with other literature prediction equations, resulting in significant coherence and practical applicability. Finally, an economic analysis was performed with HDM-4 (Highway Development and Management Tool) software, aiming to identify the roughness influence in road users’ operational costs. The results indicated that the maintenance of roughness within a limit (2.7m/km), in 10-year scenarios, can lead to an average economy of approximately R$82.000/km/year in the vehicles operational costs. In long-term scenarios (30 years), this average economy can reach R$2.768.000/km/year. Based on the results generated, it is possible to predict the structure performance in terms of IRI, in association with the asphalt mixture quality, transferring these interpretations to economic analyzes.