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This bypass phases II and III consists of a dual
carriageway viaduct and access ramps. It was the first design and
build hybrid type of contract launched by the Hong Kong
Government. The main contractor Dragages et Travaux Publics-Bachy
Soletanche Joint Venture to prepare an alternative design tender
assisted by Ove Arup (Hong Kong) Ltd.
The contractor's alternative design had to be
flexible to accommodate the contractor's chosen methods of
construction. These were defined during the early design stage but
were revised regularly in order to reduce the construction time and
cost.
During the contract several challenges arose and
required proposals which necessitated supplemental agreement with the
client, the Highways Department of the Hong Kong government. The
commercial manager on this project, Brett K. Jamieson, prepared and
negotiated the contractual arrangements necessary to met these needs.
The alternative design proposed the use of
barrette foundations instead of the engineers' original design of
large diameter bored piles. This scheme offered significant savings in
material quantities over the conforming scheme. Another of the
alternative schemes propositioned was to optimise the various cross
sections for the viaducts and ramps, to make precasting of the decks a
viable and economical solution.
 Dragages
et Travaux Publics -Bachy-Soletanche JV utilised, for the first time
in Hong Kong a method of construction which involved an overhead
gantry, pictured below, and match precast segmental balanced
cantilever units erection which was the basis of their alternative
design and which was instrumental in their winning from the Highways
Department of Hong Kong both phases.
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This
method was particularly suitable for the bypass ran
through a densely populated area and allowed
existing roads to remain open during construction and permitted early completion
of the largest single constructions contracts, HK$1 billion, at that time.