A study on merging and diverging area design for urban underground expressway

Traffic congestion has become a common problem facing the development of a city today. Considering the lack of on-the-ground resources and people's higher requirements on environment quality, greater emphasis is placed on the utilization of underground expressways to address urban traffic and environmental problems across the world. This thesis analyzes the differences between the ramps at merging and diverging area of underground and on-the-ground expressways, researches on the general layout of merging and diverging area underground expressways, speed-change lane, sight distance assurance measures, traffic facilities of urban underground expressways with reference to domestic and overseas projects and hence provides references to the merging and diverging area design of urban underground expressways in the future. (C) 2016 The Authors. Published by Elsevier Ltd.