UNPAVED ROAD MAINTENANCE MANAGEMENT IN LOCAL HIGHWAY SYSTEMS (GRAVEL, CORRUGATIONS, PANEL RATING, ROUGHNESS, INDIANA, ONTARIO, CHILE)

Unpaved roads are important in the management of county or other local highway systems but have often been overshadowed by the emphasis placed on the paved road network. This study was undertaken to analyze influencing factors, costs and existing strategies of unpaved road maintenance and to provide guidelines for road surface management by local road officials. A survey of unpaved road maintenance practices of counties in Indiana, townships in Ontario, Canada and local roads authorities in Chile indicated the need for simplicity and flexibility in road surface management at the local level. Additional analyses confirmed the impact of funding, economic development and land use on unpaved roads distribution in Indiana counties and Ontario townships. Regression relationships were determined between a visual condition rating, roughness and average speed of travel. In addition, similar relationships were determined for three road condition variables of roughness, average rut depth and clegg impact value. Independent variables with significant correlation included gradation parameters, liquid limit, road width and gradient or terrain dummy variable. Recommendations were made for gradation band specification for unpaved roads with crushed limestone surfaces in Indiana drawing from analysis of material characteristics of weak/rutted and corrugated unpaved road sections. Apart from unpaved road surface deterioration, often rarely monitored specifically in local road management, grading frequencies which were influenced by traffic volumes and type of equipment used, as well as regraveling, were analyzed as important management strategies which affect the cost of unpaved road maintenance. A modified maintenance cost accounting procedure, adaptable to microcomputer application, was developed for improved county road surface management in Indiana. The basic need of most local highway agencies is improved cost accounting by road surface type which enables life-cycle analysis. With experience, established procedures can be expanded to include road condition monitoring as part of total road surface management