Performance evaluation of gravel road: case study along shambu to amuru road segment, horo guduru wollega

Abstract

In Ethiopia Gravel roads are serving majority of the nations in major rural areas for agricultural, commercial and other social mobility purposes. Due to lack of maintenance, movement of traffic, and climatic changes over a period of time, the issues with gravel are numerous and inaccessibility of roads during rainy season, which are possible factors which affect performance of the gravel road .the road along the shambu to Amuru is one of the segment which was severely deteriorated due to the above factors. The objective of the study was to evaluate the performance of existing gravel road by taking the possible factors which can affect the performance of the road in the study area. Sampling for material laboratory(6 samples for sub grade soil and 6 for surface wearing gravel), for each sample laboratory test was done for CBR test, gradation test; Atterberg’s limits test, compaction test, specific gravity and hydrometer test. The field measurement of side drainage factor, and distress type along the study road were divided in sections. From the collected data were processed and analyzed on excel spreadsheet. The analyzed data generates the indication of the performance of the road. The results of sub grade soils were Clay and silty clay with low CBR and under S3 class and the surfacing gravel was on lower boundary condition as per ERA. This leads easily deteriorates under normal traffic. The rating of distress by type, degree and extent were determined to know the performance of the road. Erosion, rutting and potholes were the types of distress observed with high degree and extent at different section which reduces the general performance of the road. The approach recommended in this research advocates first understanding the materials, which requires inexpensive testing and simple interpretation of the test results, and then Considering the material properties, traffic, and climate; Selecting an optional maintenance strategy for distress types or decision to improve the performance this road. Thus the study recommend to immediate actions to be taken to this road to perform its function.