INTRODUCTION

The 11.8 km Route 3 Country Park Section expressway is divided into four major distinctive sections: Ting Kau Bridge and the approach viaduct, the road section leading to the southern entrance of Tai Lam Tunnel, the Tai Lam Tunnel, and the approach road and interchange system at the northern end of the tunnel. This is the most complex highway and tunnel system in Hong Kong.
        The 880-metre waterway of the Rambler Channel, which separates the Tsing Yi Island and Ting Kau, is now connected by a cable-stayed bridge which is supported by three independent towers. The foundation of the towers is composed of large-diameter bored piles, anchored to provide better stability in resisting wind. The structure of the towers was constructed in slipforms with the use of 65 mpa high-strength concrete.
        Between Ting Kau Bridge and Tuen Mun Highway there is a 510 m approach viaduct that spans Castle Peak Road and Tuen Mun Highway before it reaches the road sections leading to the southern entrance of Tai Lam Tunnel. This approach viaduct was constructed of box-section, cast-in situ concrete by a balanced cantilever method with the use of a traveler formwork system. A slip road made of precast concrete beams supported on high level piers and portals leads traffic from Tuen Mun Highway to Tai Lam Tunnel.
        The 3.8 km Tai Lam Tunnel consists of three tubes. Two tubes handle three lanes of traffic each, while the smaller diameter middle tube is a servicing duct for ventilation and maintenance purposes. The Tai Lam Tunnel was excavated using the drill-and-blast method. The contractor employed a series of computer-operated drilling rigs so that the drilling pattern could be accurately calculated. The drill holes were then filled with emulsion compound and gassing agent to produce the necessary explosion. The crushed rock was excavated and transported to the exit of tunnel by conveyor belt for disposal. The progress of excavation was about 5 m per day at the peak. As soon as the excavation was completed, a concrete lining was formed by the use of a large mechanical form system so as to strengthen and seal the exposed rock surface permanently.
        The tunnel excavation started simultaneously at both north and south ends. The works at the south and north ends were carried out by Dragages and Nishimatsu, respectively. Unlike other tunnel designs, there is a ventilation building on both ends of the Tai Lam Tunnel. This building is so designed that it also serves as the entrance to the Tunnel.
        There is a 6.2 km approach road leading traffic from the northern end of the Tai Lam Tunnel to Au Tau through Kam Tin area. In addition to the construction of the approach road, this part of the project also included the construction of the toll square and the administration building for the tunnel joint-venture consortium, as well as a slip road and interchange system leading to Yuen Long Bypass and Kam Tin Road.
        As for the construction of the approach road, there were several major rock cuts between Shek Wu Tong and Ko Po. Difficulties encountered in this part of work were mainly due to the scale of rock cutting as well as some major fractures in the cut rock requiring further stabilisation using anchor systems.

main contractor
Route 3 Contractors Consortium
Nishimatsu Construction Co Ltd/Dragages et Travaux Publics (HK) Ltd