The first and last voyage of the Central-Wanchai Bypass precast unit

The first and last voyage of the Central-Wanchai Bypass precast unit

Construction Post follows the journey of Asia’s largest precast unit as it floats into Victoria Harbour

Danny Chung:

 

Management and workers at the Gammon-Leader joint venture could be forgiven for breathing a huge sigh of relief (and perhaps have a stiff drink) on completion of a perilous operation, delivery of possibly Asia’s largest precast unit by sea.

The unit was made as part of the construction of the Central-Wanchai bypass under contract HY/2010/06 awarded by Civil Engineering and Development Department in January 2011 for a contract sum of HK$705 million.

After much delay caused by the weather, the precast unit set off with a flotilla of tugboats from Guishan Island, which is in mainland waters and located southwest of Lantau Island, to arrive in Hong Kong in the early hours of 15 July 2013 at Tseung Kwan O.

Later in the morning during lunchtime the unit was towed delicately to its final location on the western side of the Hong Kong Convention and Exhibition Centre at Wan Chai.

Heavy, intermittent rains greeted its arrival in Victoria  Harbour.

According to CEDD, the precast unit is “the size of a football pitch” measuring 120 metres long by 50 metres wide by 12 metres high and weighs 45,000 tonnes.

As an indication of its size, the volume of the unit is equivalent to the volume of water of nearly 21 Olympic standard swimming pools.

The unit was designed to float for its delivery by sea to Hong Kong.

If anyone was thinking the unit would make a grant entrance into Victoria Harbour he would be disappointed as it arrived in a manner more like a submarine rather than an aircraft carrier.

Derek Zen Wei-peu, chairman and executive director of Leader’s parent company Build King Holdings, said the delivery was made particularly difficult as many different factors, such as the weather, sea conditions, tides and availability of heavy cranes, all had to come together at the same time before the journey could be made.

In its final position, the unit sits on 51 piles and surprisingly, is not fully submerged.

“This is the design, a part is above water. This is why floating is so difficult as the centre of gravity is extremely difficult to calculate,” Zen said.

The precast unit at Guishan Island (Gammon-Leader Joint Venture - Derek Zen)

The precast unit at Guishan Island (Gammon-Leader Joint Venture – Derek Zen)

 

The precast unit leaving Guishan Island  (Gammon-Leader Joint Venture - Derek Zen)

The precast unit leaving Guishan Island (Gammon-Leader Joint Venture – Derek Zen)

 

The precast unit heading towards open sea with tugboats in attendance   (Gammon-Leader Joint Venture - Derek Zen)

The precast unit heading towards open sea with tugboats in attendance (Gammon-Leader Joint Venture – Derek Zen)

 

 

The precast unit at a brief stopover  in Tseung Kwan O after arriving in Hong Kong   (Gammon-Leader Joint Venture - Derek Zen)

The precast unit at a brief stopover in Tseung Kwan O after arriving in Hong Kong (Gammon-Leader Joint Venture – Derek Zen)

 

The precast unit arriving in Victoria Harbour with tugboat   (Danny Chung)

The precast unit arriving in Victoria Harbour with tugboat (Danny Chung)

 

Getting soaked while on the precast unit  (Danny Chung)

Getting soaked while on the precast unit (Danny Chung)

 

The precast unit being pushed into final position  (Gammon-Leader Joint Venture - Derek Zen)

The precast unit being pushed into final position (Gammon-Leader Joint Venture – Derek Zen)

 

The business end of the precast unit  (Gammon-Leader Joint Venture - Derek Zen)

The business end of the precast unit (Gammon-Leader Joint Venture – Derek Zen)

 

 

The precast unit in place after installation  (Danny Chung)

The precast unit in place after installation (Danny Chung)

 

A worker on the precast unit, seemingly walking on water  (Danny Chung)

A worker on the precast unit, seemingly walking on water (Danny Chung)

 

The banners say "Works in progress"   (Danny Chung)

The banners say “Works in progress” (Danny Chung)

 

The precast unit on 19 July 2013. The upper part of the unit remains above water according to its design  (Danny Chung)

The precast unit on 19 July 2013. The upper part of the unit remains above water according to its design (Danny Chung)

 

The scale gives an indication of its height  (Danny Chung)

The scale gives an indication of the precast unit’s height (Danny Chung)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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