Development of Condition Indicator for Managing Sealed Rural Road Networks

Abstract

Rural roads may be defined as low volume roads providing access and mobility to rural population. In developing countries they commonly represent 80% of the total road network length, playing a key role to economic and social development. Rural roads are divided into unsealed (gravel and earth) and sealed roads (thin bituminous surfaces and stabilized roads). Network management methodologies currently recommend the use of objective condition evaluations to assist decision making, such as the Pavement Condition Index for paved roads and unpaved roads. However, none of these indicators properly apply to sealed rural roads, which present different performances due climate and traffic demands. The lack of an objective indicator specially calibrated for sealed rural roads is addressed in this study. The main goal is to calibrate a condition indicator for managing sealed rural road networks. As a result of the study, a condition indicator that was preliminary developed for Double Treatment Surfaces was successfully validated for thin bituminous surfaces. In addition, a Stabilized Roads Condition Index (SRCI) was developed using field evaluations of various surface distresses observed in stabilized roads, which were contrasted with the evaluations of an expert panel. Two equations were calibrated: automated and manual SRCI equations, the former considering the collection of roughness data with response type equipment and the latter accounting for manual assessment. Finally, a qualitative scale ranging from very good to very poor condition were defined for thin bituminous surfaces and stabilized roads, considering the effect of three types of climates and roads hierarchy.