ANALYSIS AND DESIGN OF DRAINAGE STRUCTURES FOR THE RECONSTRUCTION OF ENUGU-ONITSHA EXPRESSWAY

Abstract

The deterioration of pavement is further accelerated by poor drainage, which raises the cost ofannual repair. In this project, efficient drainage system were designed and analyzed in an effort toreconstruct the frequently flooded Enugu-Onitsha express road. (From Awkuzu to Amobia flyoverjunction). In-depth knowledge about the origins and effects of a faulty drainage system was soughtafter by this project investigation. Primary data and secondary data are the methods utilized toevaluate the current drainage system of the roads under study. While conducting a field study,primary data was gathered by direct measurement, while secondary data came from the AnambraState ministry of works. According to observations made on the ground, the drainage structuresexperienced clogs caused by the dumping of trash, insufficient inlets and outlet channels, side wallfailure, and bed erosion. The roadways under investigation suffer tremendous strain and damageas a result of this dire drainage issue. The peak discharge was calculated using the logical formula.In order to calculate the design discharge for the drain and culvert, a return period of ten years waschosen. The intensity duration frequency (IDF) curve for Awka was used to determine the requiredrainfall intensities. Side drains and box culverts were planned using Microsoft Excel software incompliance with BS 8110 and BS 5400 regulations. The channels were typically constructed basedon two scenarios: an empty drainage system with earth pressure acting, and a filled drainage systemwith water pressure acting. In contrast to the design moments calculated for the box culverts, whichwere 13.69kNm, 22.29kNm, and 99.20kNm for the support, span, and walls correspondingly, thedesign moments for the side drains were 5.48kNm and 5.38kNm for the walls and base,respectively. The draft final estimated total cost for the building of the proposed drainage andculvert structures was determined to be N210,750,012 in the Bill of Engineering Measurement andEvaluation (BEME) for the project. Autocad software was used to create the roadway layout,drainage structural elements, bar bending schedule, and more. The Federal Government wasadvised to immediately begin the road's renovation in order to improve the situation for localresidents and commuters and to give the state capital's most crucial thoroughfare a facelift.