Use of longitudinal roughness data as a tool for effective maintenance management of gravel roads

Abstract

Paper presented at the 30th Annual Southern African Transport Conference 11-14 July 2011 "Africa on the Move", CSIR International Convention Centre, Pretoria, South Africa.This paper attempt to define the use of gravel road longitudinal roughness data as a significant input in Gravel Road Management System (GRMS). The data were collected from three gravel roads constructed using marginal materials in Tanzania. Two of them are in the Kilimanjaro Region and one in the Coastal Region. The rates of longitudinal roughness progression of these gravel roads were recorded using vehicle mounted bump rntegrator (VMBI) at 100 metre intervals. These data were later used to locate road sections w~th roughness at or above IRI 14 mlkm for distress survey. Roughness at or above IRI 14 mlkm is specified by the literature as the min~mum above which the gravel roads will begin to show deep depressions and erosion gulley. The correlation between longitudinal roughness and traffic volume for each road was good, and the minimum and maximum threshold at which maintenance should be triggered was set. Recommendations are made to use classified traffic volume data together with longitudinal roughness data in prioritising gravel road maintenance.