随着城市规模的不断扩大,交通流量日益增多,原有道路网络扩展受到很大限制,于是城市高架公路应运而生。上海、北京、天津、成都等大中型城市都先后构筑了大规模的高架公路体系。杭州作为国际风景旅游城市和历史文化名城,也在 With the continuous expansion of the urban area and the increasing traffic flow, the original road network has been greatly restricted. Therefore, urban elevated highway has emerged. Shanghai, Beijing, Tianjin, Chengdu and other large and medium-sized cities have successively built a large-scale elevated highway system. Hangzhou is also an international tourist city and a historic city