Design and construction supervision of Bukedea-Kabarwa 0.8km road section from gravel to bituminous standard in Bukedea district.

Abstract

This document presents a technical report on the Design and Construction Supervision of 0.8km of Bukedea-Kabarwa road from gravel to bituminous standard which was chosen to be presented for the award of Masters of Science in Construction Management of Makerere University. Existing good quality gravel is getting depleted and it is becoming increasingly difficult to find new gravel sources. Haulage distances have become longer and with the ever-increasing population, the demand for land for other economic activities has exponentially increased. The design and construction supervision was undertaken by the Author with the guidance of supervisors from Mt. Elgon Labour-based Training Centre (MELTC) and Eng. Amuya Steve Okwalinga (District Engineer) and the works department team of Bukedea District Local Government. The scope of work provides recommended design for the construction of the Bukedea-Kabarwa road. Specifically, the work involved: pavement strength assessment using a DCP, traffic assessment, material prospecting, climatic assessment, and preparation of both geometric and structural designs and construction works. The report also details the preparation of BoQs, cross-cutting issues including environmental aspects, challenges encountered and remedies provided, lessons learnt, recommendations and conclusion. The designs were prepared per the developed design manual for Low Volume Sealed Roads 2010 including pavement design manual volume III and oversea road notes by TRL. According to this manual, the pavement layers are selected based on the traffic class, subgrade class, and climatic zone over which the road is located. Traffic counts were conducted for 7 consecutive days 16 hours each day, starting at 6:00 am. And upon analysis, the traffic design class was obtained. A 24-hour count was also done on Monday and Saturday. Design subgrade classes were selected based on the CBR results from the DCP tests. Laboratory CBR values on the collected subgrade samples provided a check as well as established the moisture sensitivity of the in-situ material. For geometric design, the existing alignment was maintained as much as possible to take advantage of the acquired consolidation. The road cross section adopted had a 5.4m wide sealed carriageway, 0.45m wide unsealed shoulders on each roadside and 3% camber slopes were considered for premix (cold asphalt) adopted as an appropriate seal for the project.