Performance Evaluation Of Existing Road Drainage Structure Problems: A Case Of Sebeta City, Oromia,Ethiopia

Abstract

Drainage is one of the most important factors to be considered in the road design, construction and maintenance in different country. Poor drainage is often the main cause of road damages and problems with long term road serviceabilitythoughprovision of proper road surface drainage systems has such a great importance for the urban road to give the intended use and there by contribute to the overall development of a nation.Insufficient urban storm water drainage facility represent one of the most common sources of compliant from the citizens in many towns of Ethiopia and this problem is getting worse and worse with the ongoing high rate of urbanization in different parts of the country, especially in Sebeta city. The study was to evaluate the hydraulic capacity of the existing road drainage structures, to assess the effects of inadequate drainage structure on the road, to recommend the concerned body based on the findings in the study. An exploratory and descriptive type of methods was used to describe and evaluate the existing condition of drainage structure. Data collection methods were carried out using both primary and secondary data sources. The collected data were analyzed and presented using Arc-GIS, Glober mapper software, Digital camera, GPS device, measuring tape,surveying instruments of leveling. Hydrological analysis was carried out by using Rational Method. Hydraulic parameters are determined by using Manning’s equation. From the field evaluation, the drainage system in each road was rated as excellent, fair, good, or poor. The study reveals that more than 75% of the roadways in the selected sites were in poor drainage conditions, which lead to tremendous environmental problems. With the aid of a camera, pictures of the various degrees of drainage deterioration and its consequent effects on road pavement conditions were taken. Based on the result of this thesis the drainage system is insufficient at different area and most of the stations of the catchments were investigated that required construction of additional drainage system and its existing coverage and its proposed based on assessing hydrologic and hydraulic calculation. In Sebeta roads having inadequate drainage systems, deterioration often begins with the origin of cracks or potholes on the road pavements either at the edges or center of roadway due to different movement of traffic rate. As a result of this evaluation, it was discovered that road needs to be designed and constructed the additional size for cross fall to passes proper drainage. Such a way that they effectively drain off rain water from their surfaces into designated drainages. Finally, I recommend the concerned body to appropriate mitigation measures were proposed for required new drainage system in order to serve the area from different negative effect and drainage structures for the future purposes sustainably.