Abstract:

 Due to the high living cost in urban area, it becomes a normal behavior for people who live in county to travel through intercity roadway to urban area in the morning and back to the county in the evening. To provide infrastructure to serve for such a specific traffic model, tunnels through surrounding hills become the only choice. Furthermore, to satisfy the high living standard of the elegant urban people, the request for the quality of the pavement, landscape, ecology, environment protection, and safety precaution and facilities are even higher than expressway. In such an environmental sensitive circumstance, the tunnel itself has to serve as common duct to release the future need for construction of a separate utility tunnel. This design requirement makes the infrastructure more complicate. A successful case is described in this paper. The roadway tunnel was designed by using miniportal method to reduce the impact to ecology, by using bypass tunnel leading to the under pavement ultra high voltage manhole, which avoid an opening on the lane to reduce risk to the motorcycle, by using exclusive rescue lane to expedite the first aid, by using flexible beacons rods to separate the two way lanes, by using side flushing gallery to solve the  clogging problems of the drainage pipe, by using unsymmetric portal to partially serve as retaining wall to protect the existing walkway along the hill, and by using preembedded hole on the lining to expedite the installation of electric and mechanic facilities. All these special considerations lead to the high speed construction and excellent service quality which could serve as a paradigm for intercity roadway tunnels.

Key words: ntercity roadway tunnel in basin type urban district ecology  , environmental protection  , safety  , maintenance