The CV Division organised a technical visit to Route 8 - Ngong Shuen Chau Viaduct on 17 December 2005. On arrival, one of the resident engineers gave us a briefing on the scope of Route 8 and some special features of the Ngong Shuen Chau Viaduct (NSCV). The NSCV, part of Route 8 linking between Lantau and Shatin, was a 2.2 km dual carriageway connecting the proposed Stonecutters Bridge and West Kowloon Highway at the interchange of Cheung Sha Wan. The project commenced in April 2002 and was anticipated to be completed in early 2007. The foundation of the viaduct had been completed and the construction of the superstructure including the columns, crossheads, portals and bridge deck was underway.

The piers were moulded by means of climbing form and jump form systems. The formers were used when the piers were more than 23 m in heights. Route 8 NSCV was mainly constructed using the precast segmental balanced cantilever method. This method was similar to the cast in-situ segmental construction. The main difference was in the method of assembling the segments. Precast concrete segments were transported from the casting yard and placed in position by a gantry crane and launching girders. Segments were lifted in pairs and installed on monolithic portal frame piers, stabilised by means of post-tensioning. The gaps between the segments would be cast with in-situ concrete. One of the project site constraints was the viaduct construction above West Kowloon Highways and associated traffic diversion works. Tight control on TTA for the segment erection during midnight was implemented to ensure the works could be carried out safely and efficiently.

The participants raised questions on issues in relation to column construction method, design criteria and procedure for approving contractor proposal during the question-and-answer session. Afterwards, a tour was made around the work site and the site staff described to us the details of piers and decks construction.

On behalf of the CV Division, we thank Arup Consultant firm and their site staff for the arrangement of this visit.