Análise comparativa de métodos de dimensionamento de estradas de baixo volume de tráfego

Abstract

The road network is an important aspect of a country’s economic, social and cultural development. It is responsible for connecting rural and urban areas and for allowing the movement of people and products throughout the terrestrial territory. Unpaved roads are generally an evolution of precarious trails and dirt paths, characterized by the low cost of implementation and by tolerating large deformation. Due to their importance, it is essential that those roads are studied and designed in an appropriate and effective way so that they can meet the needs of users and ensure comfortable and safe traffic. In order to improve the conditions of the unpaved low traffic roads, this work presents a comparison between three different design methods. The first method refers to the ERA Manual (2011) which uses the CBR and traffic variables for the design. The second methodology corresponds to the Austroads method (2009) which also makes use of the CBR and traffic variables for the design. Finally, the FCE Manual (Brito, 2011) which uses only the soil classification, consequently the CBR value, to determine the thickness of the base layer of the road. For the application of the aforementioned methodologies, a road located in the Montesinho natural park region, responsible for ensuring access between two dams that supply the district of Bragança, was the target of the study. Through laboratory and “in situ” tests carried out by Cabette (2018) and Freitas (2019) it was possible to estimate some physical and mechanical characteristics on the road structure and thus determine the thickness of the base layer required for the applied conditions. The thickness of the layer designed by the three methods was similar, ranging from 10 – 15 cm in thickness. After a sensitivity study of the input variables of the presented methodologies, it was conclude that for the ERA Manual (2011) the traffic variable is the most sensitive, while for the Austroads method (2009) the most sensitive variable is the CBR value, and in relation to the FCE Manual (Brito, 2011) the resistance of the specific subgrade material and the CBR value are the most sensitive variables.