中文摘要：

基于既有路的改扩建是现阶段非洲地区诸多国家完善路网结构、提升道路等级、强化道路功能的主要方式。通过对塞拉利昂首都弗里敦东线道路61.8 km沿线特点和控制条件的分析,综合考虑工程造价、沿线地质地形、房屋拆迁、老路利用等复杂因素,应用不同专业规范,拟定了总体设计方案,提出合理可行的道路加宽原则、平纵线形拟合与优化、路基路面搭接处理、桥涵改建以及分离式路基中央分隔带排水设计等关键设计方案,并对服务水平、交通安全、生态环保进行了统筹考虑。该文所取得的成果对国内外类似工程项目具有借鉴意义。

英文摘要：

Reconstruction and extension is the main way to improve the road network,enhance the road grade and strengthen the road function in many African countries. Through analyzing the characteristics and the controlled conditions along the east line 61. 8 km road in the capital Freetown of Sierra Leone,comprehensively considering these complex factors,such as the construction costs,the geological terrain,the building removing and the utilization of existing roads,based on different professional norms,general design scheme was made,and the key schemes were proposed,such as reasonable widening principles of roads,parallel fitting and optimal design,lapping treatment of pavement and subgrade,reconstruction of bridges and culverts and drainage design of the medial strip in separated subgrade,etc.,then service level,traffic safety and ecological environment protection were generally considered. The results obtained in this paper would provide some references for similar engineering projects at home and abroad.