Kwai Chung viaduct

Designing and building, under tight deadlines, a viaduct overlooking 15 highway lanes without disrupting traffic – that was our challenge in Hong Kong. Construction of the Kwai Chung viaduct was part of a program designed to connect the new Chek Lap Kok Airport to the city centre. The project called for the construction of a 3-kilometre, 8-lane highway viaduct with precast beams, 4.2 kilometres of access ramps and interchanges with precast concrete segments, and a 5,270-metre railway viaduct with precast concrete segments. Studies for the main viaduct, support structures, and construction methods were carried out concurrently in an effort to minimise the length of the project. Full-fledged cooperation among the engineering design office, the team responsible for determining construction methods, and the builders made this project a success story.

BACKGROUND

The project to create a link between the new Chek Lap Kok Airport and the city centre in Hong Kong was launched in the late 1980s. In our response to the call for tenders for the construction of the viaduct, we decide to recommend a design variant for the deck of the main structure. In so doing, our objective was to streamline implementation methods while reducing the quantity of required materials – thereby achieving optimal competitiveness. This technical variant earned us the contract. Throughout the project, we used precast segments for the deck and concrete beams to raise the structure above the 15 highway lanes crossing half the length of the worksite.

TECHNICAL OVERVIEW

The main viaduct consists of 100 spans, ranging from 12 to 40 metres in length and 40 metres in width and widening to 60 metres where they meet the access ramps. The structure’s height above the ground ranges from 8 to 30 metres, and the cross and longitudinal slopes are 4% and 7%, respectively. The deck consists of hammerheads resting on columns or gantries by means of sliding supports. The hammerhead sections, measuring on average 3 x 2 metres, are prestressed and criss-crossed by the deck’s longitudinal cable casings. The U-shaped longitudinal girders, measuring 40 metres in length and weighing a maximum of 160 tonnes, number 8 to 13 per span. They were precast and prestressed by bar-bonding prior to transport. The rail viaduct consists of 163 spans with a maximum length of 55 metres made up of 2.5-metre-long precast segments combined with joints.
On this project, construction methods were carefully assessed to prevent interference with vehicle traffic. As a result, we used “launchers” and “falsework” resting on supports since they take up less space on the ground. Given the project’s extremely tight timetable, we needed to work concurrently on all structures and use the maximum number paving and track-laying machinery. Moreover, all such machinery was specially designed and built for this project.

Creating, in record time and without disrupting traffic, a link between the airport and the city centre in Hong Kong with a viaduct overlooking 15 highway lanes and a busy trading port was a tremendous challenge we succeeded in overcoming. Our construction methods, our decision to use precast components, and our forward-looking project coordination all enabled us to make this project a real success.

IMPACT

Among the major infrastructure projects in Hong Kong, this one – involving the construction of a link between Lantau island (where Chek Lap Kok Airport is located) and the city centre of Hong Kong – is certainly worth noting. One of the key parts of this project was the building of the Kwai Chung viaduct: a 3-kilometre structure that includes road and rail infrastructure and adds another 11 kilometres of carriageway to the existing 15 highway lanes. We needed exceptional technical methods to create the project’s structures, meet tight deadlines, and work directly above existing carriageways without disrupting traffic. This engineering structure, featuring a 3-kilometre carriageway overlooking the world’s busiest container port in close proximity to several residential towers, is an impressive showcase of our Company’s expertise and ability in developing major public works.

Project participants

Client
Hong Kong Government, Highways Department

Project management
Gifford Graham & Partners

Key figures

Implementation dates
May 1993 to January 1997

Earthworks
400,000 m3

Reinforced concrete
300,000 m3

Reinforcement
60,000 t