Geometrical design of road Case of Misibya-Ruharabuge site Asphalt roads (4.27km) in Nyarugenge district Kigali Sector, Ruriba cell

Abstract

This project made to make a design of asphalt roads of 4.27 km at Misibya- Ruharabuge site in Nyarugenge district, Kigali sector. The specific objectives of the study were to produces topographic map of the case study, to design suitable horizontal alignment, vertical alignment, cross sections of road which will facilitate these trucks and heavy vehicles and to calculate and specify the earthwork quantities (cut and fill volume). The topographic analysis of Nyarugenge District identifies 4 distinct features: Areas of gentle slopes (less than 20 percent gradient) on the ridges and along the wetlands; areas with steep slopes (more than 20 percent gradient); linear ridges running along the length of the sectors; alluvial plains along the rivers Nyabarongo and Nyabugogo. In this project, researcher collected data by using modern surveying instrument like total station, dump level et c. Laptop with engineering software CAD (computer aided design) which will occupy those topographic that for analysis and transformation to many formats. ArcGIS software for analyzing a spatial location and decision making after buffering the delimitation area for computing a number of people will be expropriated with a project AutoCAD CIVIL 3D which will be used to export and draw geometrical element of road which cross section, longitudinal section, plan view, and topographic map of the field. The average elevation of Nyarugenge District is 1,000 m above the sea level. Mount Kigali, the highest point in Kigali, has an elevation of 1,853m and the highest spot in Mageragere Sector has an elevation of 1,810 m. Due to such hilly topography coupled with large scale deforestation, soil erosion and landslides in the District are key recurrent problems faced by the City, which requires adequate soil protection measures to address this issue. Focused on the analysis of finding, our objectives was successfully achieved and showed that the existing road elements do not meet the standard road design to be used due to its damages which are lack of drainage system and other items listed in this work. With design of geometrical element of Misibya- Ruharabuge site in Nyarugenge district, Kigali sector asphalt makes the road usable in good conditions and if its maintenance is well done; handle travelling treats for users will achieve. For earthworks quantities, entered data in technical mapping system come across with a paradox phenomenon which issued by total station that affects of the road project implementation due to the increase of earthworks computation varied according to the use of different cross sectional intervals. The construction of this road is important to the Misibya- Ruharabuge site. Although a high rate of development in this site, there still problems caused by inappropriate road designed which are inhibit access to social facilities and commercial activities. This road helps to overcome those challenges.