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China's mega sea link moves forward Jun 2011
China Correspondent Zheng Yan Long
On 15 May 2011, a steel cylinder of 22m diameter and 40.5m high was vibrated into place in the seabed off the coast of China. This marked successful commencement on site of China's massive Hong Kong-Zhuhai-Macao sea link project by the Joint Venture of China Communications Construction Co (CCCC). The cylinder is the first in the retaining structure of the west artificial island for the mega tunnel-bridge highway link. Our China Correspondent Zheng Yan Long reports on the project's design, purpose, procurement model, environmental protection measures, and costs.

Vibratory driving of the first steel cylinder for the west artificial island

The Hong Kong-Zhuhai-Macao Bridge (HZMB) is another mega-project in China after the Three Gorges Dam project, the South to North Water Diversion scheme, the Beijing-Shanghai High-Speed Railway, the West to East Natural Gas Transmission project and the Qinghai-Tibet Railway. It is the link that will connect the Hong Kong Special Administrative Region to the Macao Special Administrative Region and the Zhuhai Chinese mainland. The 50km long link consists of three cable-stayed bridges, two artificial islands, a 6.7km immersed tube tunnel with associated viaducts, relevant link roads, and the necessary boundary crossing facilities (Fig 1). When the dual three-lane highway is complete, it will become the longest sea-crossing project in the world and will change fundamentally the transportation situation in the Pearl River Delta that currently relies heavily on waterborne traffic.
Fig 1. Layout of the Hong Kong-Zhuhai-Macao sea-link project

Fig 1. Layout of the Hong Kong-Zhuhai-Macao sea-link project

Contract model
Design-build is the procurement model adopted by the governments for this mega project in order to commence construction without delay and promote the socio-economic development of the region. On 19 November 2010, the HZMB (Hong Kong-Zhuhai-Macao Bridge) Authority awarded the contract to a consortium led by the China Communications Construction Co with JV partners AECOM Asia Company Ltd, Shanghai Urban Construction (Group) Co, China Highway Planning and Design Institute Inc, COWI A/S, Shanghai Tunnel Engineering and Rail Transit Design and Research Institute and CCCC Fourth Harbor Engineering Investigation and Design Institute.
The HZMB will be of strategic importance to the further economic development of Hong Kong, Macao and the Western Pearl River Delta region (Western PRD). It will reduce transportation costs and travel time significantly and provide benefits far beyond the immediate area. With the HZMB, the Western PRD will fall within a reachable three-hour commuting radius of Hong Kong. This will enhance the attractiveness of the Western PRD to external investment, which is conducive to the upgrading of its industry structure. Hong Kong will benefit from this new economic hinterland, with its vast human and land resources, providing ample opportunities for Hong Kong businessmen to expand their operation in the mainland. It will also benefit various sectors in Hong Kong, including tourism, finance and commerce. In particular, it will enhance Hong Kong's position as a trade and logistics hub as commerce make use of the airport and container ports in Hong Kong for goods from the Western PRD and other regional areas of mainland China, including Western Guangdong and Guangxi.
Island and tunnel combination
The tunnel solution is adopted to provide access by container vessels of up to 300,000-tonne class to Pearl River Delta ports. The 6.7km long immersed tube lies under a maximum water depth of 44.5m and comprises 33 elements with a typical element dimension of 180m long x 37.95m wide x 11.5m high (Figs 2 and 3). Two artificial islands achieve the transitions between bridge and tunnel and will also be used as bases for project management, highway maintenance and rescue, tourism and sightseeing.
Fig 2. Longiditual alignment of the immersed tube tunnel

Fig 2. Longiditual alignment of the immersed tube tunnel

Fig 3. Crosssection of a typical tunnel element

Fig 3. Crosssection of a typical tunnel element

The islands and the tunnel, known as the Island and Tunnel Project, is the most technically demanding aspect of the HZMB Project and based in a complicated navigational environment. Among the key technical challenges are:
• for prefabrication of large volume concrete elements and crack control, synchronous jacking, positioning, and immersion control of the huge segmental elements;
• techniques for improving the foundation of the immersed tube elements with driven steel tubular piles and sand replacement in the sea;
• construction techniques of the artificial islands on the very soft-plastic clay in the sea;
• construction techniques of the interface of the tunnel and bridge; and
• mitigation measures to protect vulnerable environments.
To overcome these challenges, a large number of systems, specialized equipment and techniques have been, are, and will be developed.
Environmental concerns
The main bridge is located in the Conservation Region of Chinese White Dolphin in the Pearl River Estuary. Mitigation measures will be taken to minimize the water, air and noise disturbance to protect the dolphins. High density construction will be avoided during the breeding period; an exclusion zone will be established around areas of piling and dredging works; restrictions are applied to working vessels to reduce their disturbance to dolphin activities; silt curtains and closed-grab techniques will be used during dredging and dumping operations to minimize water quality degradation which might impair the immune system of the dolphins; percussive piling will be avoided and bubble curtains/jackets will be employed to prevent acoustic disturbance of the dolphins' sonar navigation system.
Table 1. Construction timeline of the Island and Tunnel Project
Construction items Milestone target date (months duration)
Construction commencement time
Immersed tunnel
Completion of prefabrication of first batch of tunnel elements
Commence fabrication of initial tunnel element E01
Hand-over of all interfaces for traffic engineering works
December 2010
End of July 2012 (25 months)
End of September 2015 (58 months)
West artificial island
Completion of island and tunnel interfaces and preparation for connection and immersion of initial immersed tunnel element
Completion of artificial island
End of October 2012 (23 months)
End of September 2014 (46 months)
East artificial island Completion of artificial island End of May 2015 (54 months)
Construction completion time March 20, 2016
Furthermore, once dolphins are found within the zone, works will stop until they leave. All will be monitored independently by experienced independent dolphin specialists.
Financing
The overall estimated cost of the project is about RMB 73 billion or about US$ 10.7 billion. To have a better control over the future tolling of the link, to attract more traffic and enable better economic development of the Western PRD, the HZMB Project is financed by the three associated governments, instead of by the previously planned private sector.
Fig 4. Visualization of the west artificial island

Fig 4. Visualization of the west artificial island

The China's Mainland Government, the Macao SAR Government and the HKSAR Government will be responsible for the funding, construction and operation of the respective Boundary Crossing Facilities and link roads within their territories, while the HZMB Main Bridge, which accounts for RMB 34.7 billion of the total, will be constructed jointly by the three governments.
The three governments will altogether contribute RMB 15.73 billion, with the Mainland, HKSAR and Macao SAR contributing RMB 7 billion, RMB 6.75 billion and RMB 1.98 billion respectively. The balance will be financed by the procurement consortium led by the Bank of China.
Construction schedules for all elements of this massive project are programmed to meet a completion date in 2016.

References
Item for Public Works Subcommittee of Finance Committee, PWSC (2009-10)17
Second Expert Panel meeting materials, Island & Tunnel Project of Hong Kong-Zhuhai-Macao Bridge Esther Cheung, Albert P.C. Chan: Is BOT the best financing model to procure infrastructure projects? -
Journal of Property Investment & Finance, Volume 27, Issue 3, 2009 IBC Paper No 14/2009, Hong Kong - Zhuhai - Macao Bridge
Project construction techniques

           

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