análise do impacto do período de projeto de pavimentos no custo global de obras rodoviárias

Most projects for the construction of big highways in Brazil are based on conventional design methods. It is also common practice in Brazil to adopt a period of ten years to account for the traffic load when designing flexible pavements. However, some highway infrastructure projects are rather expensive and the costs related to earthworks or special structures, such as bridges and drainage, can significantly overshadow the cost of the pavement construction. Therefore, it is important to evaluate the economic impact of considering longer design periods, still in the stage of study of viability of a big highway project. The objective of this paper is to show the relation between overall cost and design reliability with the increase of design period. Five big highways infrastructure projects under construction by the Brazilian National Department of Transport Infrastructure (DNIT), in the context of the Program for Growth Acceleration (PAC), are investigated as case studies. The cases include two highways with rigid pavement and three others with flexible pavements. The results show clearly that a significant increase in design period does not impact significantly the overall costs. In all cases, doubling the period of design would increase the of overall cost of the contract by less than 4%. Perhaps most importantly, the results of mechanist analyses show that the probability of failure of the pavement due to fatigue cracking of the concrete layer decreases when longer design periods are adopted. In order works, the adoption of longer design periods not only has little impact on the overall costs of big highway construction projects, but also lead to pavements with higher design reliability.