Aurecon’s role covered Contract 824 – the Ngai Tam Mei to Tai Kong Po 2.6 km twin tunnels. Aurecon was appointed by the Kier-Kaden Joint Venture as designer for both the major geotechnical and civil temporary works, and value engineering designs.
Aurecon was responsible for a variety of elements on the project including temporary support for the shafts at Ngai Tam Mei and Tai Kong Po, plus the design of temporary access bridges that were required to enable access for heavy construction vehicles to the remote site locations. The upper rectangular part of the Ngai Tam Mei shaft was constructed with traditional steel piling and strutting, while the lower circular portion was constructed with permanent reinforced secant piles.
Access to the tunnels beneath ground level was from deep shafts. Both the design and construction of the shafts at Ngai Tam Mei and Tai Kong Po were on the project’s critical path.
At Ngai Tam Mei, the project team innovatively designed the upper soft ground portion of the shaft to be constructed in two halves, enabling the tunnelling teams to start excavating the rock below, well in advance of the original programme.
The shaft at Tai Kong Po was to be used to store a ventilation building and therefore its size was larger than necessary for the day-to-day construction requirements for tunnelling below. To enable earlier access for this tunnelling, a second temporary, and smaller shaft, was designed and constructed adjacent to the main shaft. This shaft was later backfilled.
Smart design thinking contributed to achieving Contract 824 on time and on budget. The XRL will connect with the 25 000-km national high-speed railway network and will enhance Hong Kong's role as the southern gateway to Mainland China.