盆地型都会联外公路隧道之特殊设计考虑

Special Design Considerations for Intercity Roadway Tunnels in a Basin Type Urban District

盆地型都会之特色为寸土寸金,都会区外居民进入区内就学、工作及返回区外住居成为交通常态,为应付此种放射状之车流,常需构筑穿越群山环抱之联外公路隧道,复以都会生活族群特殊之政商背景,对路面质量、视野景观、生态保育、防灾救难均有高于一般公路隧道之要求,隧道本体并须兼做为共同管道以容纳电力电信之需,增加整体之复杂度。用案例说明以缩小洞口开挖范围、隧挖取代明挖等方式保育生态;以侧壁绕行隧道进入电缆人孔以取消人孔盖来提升路面质量,保障机车安全;提供救灾专用道以供救护车快速救治伤员;以可回复式导标版软性分隔车道及防眩,提升安全;提供侧壁排水盲管清洗孔以供长期维护、阻塞时泄压以防衬砌渗漏;以不对称洞门使洞口假隧道兼作挡土墙,以维持墙背缓坡供重建原有登山小径景观,及衬砌上预埋管线槽固定架螺栓孔,以缩短施工工期等一系列特殊设计考虑,成效卓著,提供了模范指标。

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.