| In 1989 the Government decided to develop
a new international airport for Hong Kong
on a site formed from Chek Lap Kok, an
island just 3 km off Lantau Island. This
was to replace Kai Tak International Airport,
which would reach maximum capacity in
the mid 1990s. |
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| Nine further infrastructure projects
- collectively known as the Airport Core
Programme (ACP) - were associated with
the development of the new airport. These
were Tung Chung New Town, the North Lantau
Expressway, the Airport Railway, the Lantau
Link, the Cheung Tsing Tunnel on Route
3, the West Kowloon Reclamation, the West
Kowloon Expressway, the Central and Wanchai
Reclamation, and the Western Harbour Crossing. |
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| Unlike all the other ACP projects, the
Western Harbour Crossing (WHC), now more often
called the Western Harbour Tunnel (WHT),
is a franchised infrastructure, completely
financed by the private sector at a cost
of HK$7 billion. It remains Hong Kong's
single largest private sector transportation
project. |
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| Location Linkage |
| The Hong Kong portal of WHT forms the
southern gateway of Route 3, the strategic
north-south road corridor that traverses
the western part of Hong Kong. The tunnel
thus links major population centres in
Hong Kong, the container port in Kwai
Chung and the Hong Kong International
Airport, etc. It also opens up the northwestern
New Territories and connects with many
superhighways to Guangdong via Lok Ma
Chau. |
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| WHT not only releases the traffic stress
at the other two cross-harbour tunnels,
it also shortens your travelling time
between Hong Kong Island and Kowloon. |
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| Project Scope |
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| The construction of WHT
was split into several sections: |
| 1. Elevated Bridges in Sai Ying
Pun on Hong Kong Island |
| The existing elevated section of the
east-west distributor road on the north
of Hong Kong Island was extended towards
west to form the first section of Route
4, the planned coastal road to Aberdeen.
The elevated length of Route 4 contained
17 separate bridges and ramps. The ground
level roads were connected to the existing
road network. It took 43 months to finish
the construction. |
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| Among the works needed to accommodate
the Western Harbour Crossing, additional
works such as utilities diversions and
reprovisioning works for the control of
public usage of the sea wall for cargo
handling were also required. These were
carried out early in the contract to make
site areas available. A new footbridge
was erected over the existing Connaught
Road West. |
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| 2. Tunnel Approaches |
 The
tunnel approach roads were built on an area of reclaimed
land which had been built mainly by public dumping
over the years. This area was bounded on the north
by the harbour and on the south by the existing Connaught
Road West. The area presented constraints for the
road layouts, but these were overcome by a horizontal
alignment meeting the required design criteria. |
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| 3. Cut-and-cover Tunnel and Sai
Ying Pun Ventilation Building |
| To accommodate the climbing lane in
the southbound tunnel, the 350 m cut-and-cover
tunnel was designed to curve to the open
ramp. The open ramp then connected the
cut-and-cover tunnel to the road networks
in Hong Kong. The Sai Ying Pun ventilation
building was located close to the edge
of the harbour sea wall. It marked where
the tunnel construction method changed
from cut-and-cover to immersed tube units.
The ventilation building housing 18 reversible
axial fans was built on top and linking
up between the cut-and-cover tunnel and
the immersed tube unit. Ventilation of
the cut-and-cover tunnel was from overhead
ducts formed below the roof slab by suspending
precast concrete panels. |
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| 4. Immersed Tube Tunnel |
| The immersed tube formed a straight
alignment between the two ventilation
buildings on each side of the harbour.
The 1.36 km tunnel was made up of twelve
immersed tube units, each 33.4 m wide,
8.57 m high and 113.5 m long. The average
weight of one unit was about 35,000 tonnes.
Each unit had two side ventilation ducts
and two three-lane carriageway tubes.
The twelve units were cast in three batches
in a dry-dock casting basin at Shek O
on the south side of Hong Kong Island.
Four units were cast at a time and once
completed were floated out to a temporary
anchorage at Tseung Kwan O to be fitted
for sinking. This procedure allowed the
casting basin to be pumped out and made
ready for the construction of the next
batch of four units. |
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| Construction of the first batch four
units started in June 1994 and they were
floated out in January 1995. The first
unit was sunk into position adjacent to
the Sai Ying Pun ventilation building
in March 1995. The final unit, No. 11,
was sunk into position at the end of April
1996. |
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| The units were placed in a dredged trench,
backfilled with general fill and then
protected by a rock blanket 2 m thick
with rock armour protection strips to
prevent damage by dragging anchors. |
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| 5. Cut-and-cover Tunnel and Ventilation
Building at West Kowloon |
 The
West Kowloon ventilation building, similar to that
at Sai Ying Pun, gave the tunnel a strong visual landmark,
standing as it did in isolation on a large expanse
of flat reclaimed land. The cut-and-cover tunnel rose
from below the ventilation building to the portal
and open ramp. The open ramp fanned out so that traffic
can access the toll booth. |
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| 6. Toll Plaza |
| A total of 20 toll lanes were originally provided,
and the middle four are reversible giving
the option for up to 12 lanes to be operated
should traffic in one direction require
added facilities. Up to eight lanes are
provided with automatic toll collection,
although only six are operational at present.
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| Two bus bays are provided at either
side of the toll plaza and a pedestrian
footbridge has been constructed to give
access across the wide toll plaza area.
The ground level carriageways link up
with the West Kowloon Highway about 300
m north of the toll booths at the project
boundary. |
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| 7. Administration Building |
 The
Administration Building is situated at the east side
of the open ramp and adjacent to the toll plaza. The
three-storey building in oval-shaped was built with
the latest environmental design. A solar control
feature has been fitted on all windows so as to reduce
loading on the air conditioning systems and improve
exterior vision. |
| Reference : |
Thomas Telford Limited - Journals on Line.
"Civil Engineering Special Issue : Hong Kong
International Airport, Part 2: Transport Links
/ November 1998 - Paper 11526 Western Harbour
Crossing, Hong Kong - a successful BOT model" |
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Driver Zone