ROUTE RE-ALIGNMENT SURVEY FOR COST EFFECTIVE CONSTRUCTION OF A CONNECTING BRIDGE OVER SULEJA-DAM

Abstract

Before the construction of Suleja dam in 1993, people and goods were conveyed / transported freely through the old road because the small river separating the adjoining communities (Ija, sabo bwari, ija kuchiko and ija koro) had a small bridge that accommodated vehicular and other means of transportation. However, because of the construction of the dam, the communities once connected are now separated in their economic and social interaction. In view of this; this research was carried out with the aim of realigning the old road to accommodate a shorter and cost effective bridge over the dam. Differential Global Positioning System (DGPS) receivers were used to set-out the new alignment while an Automatic level was used to transfer height from the Benchmark to the lake. Eco Map 50s was used to carry out the strip sounding over the proposed bridge route to determine the water depth. A total length of 2.919km was obtained from the proposed realignment as against a distance of 3.038km of the old alignment. As a result, a proposed bridge length of about 514m was achieved as against the 740m of the old alignment. AutoCAD 2010 and Carlson were used to plot the alignment, as well as the longitudinal profile and length calculation. In addition Layer stacking of the existing alignment and new alignment of the area on satellite imagery of the site was also carried-out in order to depict the differences between the existing road and the proposed realignment.