3.1
General Alignment and Key Elements
As discussed in
Sections 2.3 to 2.5,
a number of alignment options have been considered for the west, east and central
portions. These options have been evaluated by considering a number of factors
including engineering, public comments, environmental factors etc. The
preferred alignment for each portion has been recommended and Figure 1.1 shows the
entire preferred alignment.
A brief summary of key elements of the Project
is given below and more details are given in the following sections.
3.2.1
Tunnel Sections from Yau Ma Tei to Ma Tau Kok
The total length of the tunnel section between
Yau Ma Tei and Ma Tau Kok is about 3,325 m. The drill-and-blast rock tunnel in the
central portion is approximately 2,760 m, which has been optimized to create land
easement, minimizing building impact in urban area, geological condition,
future private redevelopment constraints etc.
Cut-and-cover tunnels will be proposed at both ends of the tunnel where
rock cover is not sufficient. The cut-and-cover section in Yau Ma Tei will be
approximately 400 m long while that in Ma Tau Kok will be 135 m.
The above figures are rounded up slightly to
cover for the different lengths of the two bores. The actual lengths may vary depending on the
eastbound / westbound bore and on the interpretation of the change in tunnel
types (i.e. the seawall cope line has been taken as the end of the marine
section).
Further elaboration on the construction methodologies
of the proposed CKR are presented in Section 3.5.
The total length of the underwater tunnel
between Ma Tau Kok and Kai Tak is about 370m long. As
discussed in
Section
2.4, a number of alignment options have been
considered for the tunnel connecting Ma Tau Kok and Kai Tak, and the current
option of underwater tunnel at Kowloon Bay is chosen based on various
considerations including minimizing the disturbance to public/marine
facilities, environmental impacts, extents of temporary reclamation and
technical feasibility.
The tunnel is deepest at Ma Tau Kok and
shallowest at Kai Tak. For most of its length the underwater
tunnel has its ventilation ducts above the tunnel road portion and the tunnel
width is approximately 43m. At the eastern end of the underwater tunnel, a
side-duct ventilation arrangement is adopted to reduce the height of the
underwater tunnel section so as to ensure the tunnel structure remains beneath
the existing marine bed levels and the width is at approximately 53 m.
3.2.3
Yau Ma Tei
Interchange of the West Kowloon Highway and Associated
Road
Network in West
Kowloon
CKR will have the
following slip road connections in West Kowloon, as also illustrated in
Figure 3.1.1:
·
Slip Road A – CKR westbound to Lin Cheung
Road southbound;
·
Slip Road B – CKR westbound to Western Harbour
Tunnel southbound;
·
Slip Road C – CKR westbound to Lin Cheung Road
northbound;
·
Slip Road D – CKR westbound to West Kowloon
Highway northbound;
·
Slip Road E – West Kowloon Highway southbound to
CKR eastbound;
·
Slip Road F – Lin Cheung Road southbound to CKR
eastbound; and
·
Slip Road G – Hoi Po Road northbound to CKR
eastbound.
CKR will have a number
of strategic connections to/from other main roads in eastern Kowloon as follows
and as shown in
Figure 3.1.4:
·
Slip Road S1 – CKR eastbound to Kai Cheung Road
eastbound;
·
Slip Road S2 – Kai Cheung Road westbound to CKR
westbound;
·
Slip Road S3 – CKR eastbound to Kai Fuk Road
eastbound;
·
Slip Road S4 – Kai Fuk Road westbound to CKR
westbound;
·
Slip Road S5 – CKR eastbound to Kai Tak
Development;
·
Slip Road S6 – Kai Tak
Development westbound to
CKR;
·
Slip Road S7 – CKR eastbound to Road D2;
·
Slip Road S8 – Road D2 to CKR westbound; and
·
Slip Road S9 –
Kai Fuk Road westbound to Kai Cheung Road eastbound.
A landscaped deck will be provided at the
portal of west portion. The "Yau Tsim Mong District Aspirations
Study Report" published by YTM District Council in April 2010 (http://www.ursreview.gov.hk/eng/doc/YTM_DAS_Report_final.pdf) referred to the
area of YMT around Kansu Street being developed as an intersection area for
north-south and east-west movement of pedestrian and vehicular traffic.
There is a
need to provide a landscaped deck over a portion of CKR’s depressed road at the
Kai Tak Development area in between the east tunnel portal of CKR and Road D3
within the Kai Tak Development according to the Kai Tak Outline Zoning Plan No.
S/K22/4. According to the latest design, open space
would be provided at the top of the
landscaped deck.
The existing Kowloon City Ferry Pier PTI requires
re-provisioning for the duration of CKR east end construction activities to
provide working and construction space. The re-provisioned permanent PTI will
remain in the same vicinity as the existing PTI shifting slightly towards To
Kwa Wan Road. A landscaped deck on top of the re-provisioned PTI has been
proposed to mitigate noise impact of the PTI.
3.2.6
Demolition and
/ or Re-provisioning Works
The Project will include the following demolition and / or
re-provisioning works which are not designated projects under Schedule 2 of
EIAO.
Yau Ma Tei Multi-Storey Car Park Building
The CKR tunnel will pass beneath the existing YMT
multi-storey car park building. As the
tunnel tubes are too close to the foundation of the building, the stability of
the building will be affected and need to be removed. Before the commencement of the demolition of
the building, decantation of the Yau Ma Tei Public Library and the other
government offices in the building is required.
Yau Ma Tei
Public Library will be re-located to a temporary building at Shanghai Street/Market
Street Playground during CKR construction stage. After CKR, the library will be moved to a new
building at the location of the original position of multi-storey car park
building.
The existing
government offices in the building will be re-located to adjacent area during
CKR construction stage. Co-ordination
with relevant government departments e.g. Government Property Agent (GPA) for
the temporary and permanent arrangements are on-going.
YMT Specialist Clinic Extension Building
The existing YMT Specialist
Clinic Extension Building (SCEB) at Battery Street is also required to be
demolished for the construction of CKR.
A new building will be constructed in Queen Elizabeth Hospital to house
the special clinic.
The existing
Methadone Clinic at the ground floor of SCEB will be relocated to the adjacent
Jockey Club Polyclinic Building.
Jade Hawker Bazaar
The existing single
storey buildings for Jade Hawker Bazaar at Battery Street are located on the
alignment of CKR. The buildings require
removal for the construction of cut-and-cover tunnel. A temporary building will be built on the
existing Kansu Street Rest Garden on the south side of multi-storey car park
building to house the affected hawkers of the Jade Hawker Bazaar.
After completion of
the cut-and-cover tunnel, the temporary
building will be removed and the hawkers will be decanted to the new buildings
located at the original Jade Hawker Bazaar position.
The existing area
(under short term tenancy) for Hong Kong Automobile Association is required for
CKR construction site and therefore needs to be cleared before the commencement
of CKR construction.
Section of Gascoigne Road Flyover
The section of GRF flyover between Temple Street
and Ferry Street will be reprovided for the construction of CKR tunnel and removal of the existing
multi-storey car park building. It is
understood that the traffic on the flyover has to be maintained during
construction stage and therefore a temporary flyover will be
provided in its north side to divert the traffic before demolition of the
affected section of the existing flyover.
Landing Step for Temporary Relocation of Ma Tau Kok Public Pier
In order to facilitate the construction of
underwater tunnel, the existing Ma Tau Kok Public Pier is required to be
demolished. A temporary Ma Tau Kok Public Pier needs to be provided to maintain
the original ferry route and minimize the impact to the passengers and users in
the district. A landing step is proposed at LCSD promenade (GLA-TK 618 TGLA)
near King Wan Street for temporary boarding of the public between the bus
drop-off area on King Wan Street and temporary Kowloon City Ferry Pier PTI
during CKR construction stage. A small portion of the waiting area inside To
Kwa Wan Vehicle Examination Centre is required to provide a minimum width of 2m
between the temporary relocated Ma Tau Kok public pier and waiting area (GLA-TK
442 TGLA). Temporary covered walkway
which directly connects the landing step and temporary PTI will be provided for
the pedestrians as a safe, convenient and pleasant access. The public pier will
be re-provisioned after the commissioning of CKR works and consistent with the theme
of Kai Tak Development. According to the current construction methodology,
dredging is not required for the temporary relocation of Ma Tau Kok Public
Pier.
3.2.7
Conservation of the Yau Ma Tei Police Station
The cut-and-cover tunnel of CKR will be constructed partly beneath the building of YMT
Police Station, therefore the police station needs to be decanted prior to the
commencement of construction. After the commissioning
of CKR, the existing police station building will be used for
other, to be determined, purposes.
The CKR tunnel will
run underneath the existing new wing building and provide around 2.3 m
clearance with the old wing building.
The existing new wing building is a four storey building supported by
concrete friction piles. Construction of
tunnel underneath the building will require to remove those affected
piles. An underpinning scheme is
proposed to transfer the existing column loadings to a deeper rock
stratum. The supporting system includes
cutting the existing ground floor slab to expose the existing pile caps and
then constructs transfer beams at both sides of the pile caps. The transfer beams will tie up with the
existing caps. Loadings of the transfer
beams will be transferred to the rock socket piles installed at the two ends of
the beams. For the old wing of the
police station, Tube a Manchette (TAM) grouting will be carried out for the area before the construction
works of CKR. It is anticipated that
effect on the building will be controlled below an acceptable level.
Apart from an investigation on the necessary measures to protect and preserve
Yau Ma Tei Police Station during the construction of CKR, a study on the Yau Ma
Tei Police Station revitalisation has been undertaken which aimed at
investigating the best approach and the possible adaptive re-use options for
the Compound after the Police Force has relocated. The findings discussed
within the document “Report on Revitalisation of Yau Ma Tei Police Station”
assessed the condition of the Compound, providing appraisals of the cultural
significance of the Compound, a SWOT analysis, recommended conservation policy,
suggested/ discussed possible options for adaptive re-use and summarize views
collected from stakeholders and the public.
From the visual inspection carried out so far both the Old and New Blocks
of the Compound appear to be in fair condition with only minor defects such as
water leakage and cracks on renderings.
Yau Ma Tei Police Station gives an indication of the original coastal
line and has been an inseparable part of the GIC cluster or the group of
cultural assets in Yau Ma Tei, and thus it is opined that it carries high
contextual value in the district level. On the other hand, it carries medium
architectural value for it is an example of neo-classical building of fair
architectural merits. It carries medium historic value for it is the oldest
police station in an urban context that still survives in Hong Kong, and both
the Old and New Wings add up to give a complete story of the evolution of the
police station building and the Hong Kong Police Force over time. It is however
observed that the community has built up deep bonding with the building, that
they see it as one of the important cultural assets in the district that helps
define the identity of the district. It is therefore opted that it carries
fairly high social value.
In view of the above, conservation of the Compound in total, i.e. both
the Old and New Wings, is the most desirable. The Compound has strength in
terms of location and strong contextual bonding, weakness in terms of the
ability to adapt new functions, opportunity to further enhance the strong
contextual bonding within the area and to give interpretation to explain the
future generation about the history and culture of the district, as well as
threats by the construction of CKR and inappropriate adaptive re-use.
Other than the Old and New Wings, the Yau
Ma Tei Police Station also includes a 1-storey kitchen and laundry block and
car port. However, as stated in the report on the Consultancy for Conservation Study of Yau Ma Tei Police Station at No.
627 Canton Road, Kowloon (July 2009), “ The 1-storey kitchen and laundry
block and the car port, are at low significance and lack of architectural
interest. Hence, the 1-storey kitchen and laundry block and the car port would
be demolished.
The Ma Tau Kok
area is located in south-western part of Kai Tak Development (KTD). It comprises the existing waterfront area at
Ma Tau Wai/To Kwa Wan bounded by To Kwa Wan Road and Yuk Yat Street to the west
and Bailey Street to the south. Ma Tau
Kok is an old urban district in Kowloon, which has been substantially developed
for private residential, public housing and industrial uses. The Ma Tau Kok area currently consists of a
mix of residential, industrial, open space government, community and pier
uses. Recent redevelopment projects
include the Grand Waterfront residential development, which comprises 5
residential towers.
The Ma Tau Kok
Area covers land on the waterfront of Victoria Harbour. For any development proposal affecting such
land, due regard shall be given to the “Vision Statement for Victoria Harbour”
published by the Town Planning Board (the Board), the requirements under the
Protection of the Harbour Ordinance (Cap. 531) and the Harbour Planning
Principles published by the Harbour-front Enhancement Committee. The principal
objective within the planning area is to provide for the introduction of
continuous public accessible open spaces at the waterfront, which is set as a
strategic planning objective that seeks to secure the creation of continuous
publicly accessible waterfront open space extending from Kowloon East to the
Runway District.
The Ma Tau Kok
waterfront areas therefore has been planned to develop as part of a continuous
waterfront promenade connecting Kwun Tong, Kai Tak, Ma Tau Kok and To Kwa Wan
waterfront as a long term planning proposal. The approved EIA for Kai Tak Development has
also highlighted these open space developments along the waterfront. Besides
providing pleasant public access to the harbourfront, the waterfront promenade
will also act as key green connectors linking up individual open spaces,
residential areas and surrounding areas.
Re-provisioning of the existing Kowloon City
Ferry Pier Public Transport Interchange (PTI), including
all bus, green light bus, drop-off area, taxi stand etc, is required to facilitate the construction of
the cut-and-cover tunnel. According to Chapter 9, Section 4.2.14 of Hong Kong
Planning Standards and Guidelines (HKPSG), it is recommended on the planning
point-of-view to “locate the facilities (i.e.
the PTI in this case) so that there is no
line-of-sight of the noise sources at the noise sensitive uses”. Potential
noise source of the re-provisioned PTI has been assessed in Chapter 5 and landscape
treatment will be considered as far as possible to enhance the urban
environment.
3.2.9
Ventilation
Buildings and Administration Building
The exhaust
emissions of motor vehicles using the tunnel will require a tunnel ventilation
system to ensure that the air quality within the tunnel meets the air quality
objectives stipulated in the EPD “Practice Note on Control of Air Pollution in
Road Tunnels”. Air quality concerns at the tunnel portals have led to the
intent to achieve limited portal emissions, requiring that the ventilation
system extracts air constantly from the tunnel to capture the traffic generated
airflow through the tunnel. An air purification system (APS) is needed to treat the air discharged by the tunnel ventilation
system to reduce the air quality impacts at air sensitive receivers and achieve
the air quality objectives (AQO). Separate from this need for an air
purification system, cost benefit analysis using the acute and chronic
health benefit if air purification system is adopted suggests that the
provisions of air purification systems would be justified.
To enable the
tunnel ventilation system and air purification system to be readily
maintainable (without lane or tunnel closures), the majority of the tunnel
ventilation and air purification system equipment will be located in
ventilation buildings, connected to the tunnel through adits and shafts.
All the tunnel
control and monitoring systems will be connected to the Administration
Building. Tunnel operators shall
24-hourly station in the building to control the tunnel systems and monitor the
tunnel operation.
Air
Purification System
The proposed
APS for CKR schematically comprise of 2 main processes.
The first part
involves the use of Electro-static Precipitators (ESP) to remove portion of
particulates including PM10 and PM2.5 from the air extracted from the tunnel.
ESP has been
successfully used in the past 90 years for effective removal of particulates
from airstreams, especially for processes requiring large and steady flow. For instance, typical applications include
boilers, incinerators, coal-burning plants and many other industrial processes
have employed this technology to remove particulates in the air, however their
application for road tunnels (where pollution concentrations are notably lower)
is a more recent development.
The basic
operation of ESP is as follows:
·
Incoming air
first passes through an ionization chamber in which the particulates are
ionized into both positive and negative ions under a very strong electric field
(i.e. generated by a high voltage in the order of 10kV). This phenomenon is called “corona discharge”.
·
The air then
passes through a precipitation chamber where the ionization particulates are
collected by the alternately charged electrode.
·
The collection
efficiency of the ESP would however decrease when the electrode is accumulated
with more particulates. Hence, the
precipitation chamber would need to be cleaned periodically, or as required.
The effluent
from the water jet system would be cleaned by a filtration system to remove the
particulate matter, and the recycled water would be reused for electrode
cleaning again. The particulate matters
filtered (in the form of a cake or a sludge) would need to be separately disposed.
After passing
through the ESP, the air would be fed into a NO2 removal system to
reduce the NO2 concentration before it is eventually discharge to
the atmosphere. There are generally two
broad approaches adopted in typical NO2 removal systems.
·
The first
approach consists of specially prepared activated carbon which is contained in
box-shaped container with wire mesh on both sides and installed on a support
structure downstream of the ESP. The
activated carbon filter media would need to regularly replace (typically every
three years).
·
The second
approach consists of decomposing modules which are periodically regenerated on
site by “washing” with chemical solutions such as ammonia, potassium hydroxide
or sodium sulphite etc., chemical solutions which depend on the proprietary
design of the NO2 removal system.
The “washing” process would need to be conducted every few weeks.
The specific
process to be adopted shall be determined at a later stage through the supplier
pre-qualification process.
3.2.10
Enclosures and
Barriers
Base on the findings of noise impact
assessment, noise mitigation measures in the combination of noise enclosure,
semi-enclosure, cantilever noise barrier and vertical barriers will be provided
at the section of west portion along some slip roads connecting to CKR tunnel,
re-provisioned Gascoigne Road Flyover (Ferry Street section), re-aligned Hoi
Wang Road and widening of Lai Cheung Road.
The
construction of CKR is to commence in 2015. The construction works would take
about 5 years and the target commissioning date is around
end 2020. The construction programme is presented in
Appendix 3.2.
3.4
Material Changes to Exempted Designated
Projects
Clause 1.4 of
the EIA Study Brief ESB-156/ 2006 states that
“The Project may also include changes to
associated roads that constitute material change(s) to exempted project(s) to
be identified under Section 2 (xii) below.”
Also under
Section 2 (xii), it states the need to
“To identify within the scope of the EIA
study as defined in Section 3.2 below, any individual works that constitute
material change(s) to exempted project(s) or other designated project(s) under
the EIAO.”
Given these 2
provisions in the EIA Study Brief, it is considered that it has built-in
flexibility to include the following exempted designated projects in the EIA
without having the need to apply for revision of this EIA Study Brief
ESB-156/2006 or to apply for a new one for this item in particular.
3.4.1
Re-provisioning
of Gascoigne Road Flyover (GRF) (Kansu Street Section)
The section of
existing GRF between Ferry Street and Temple Street will have to be demolished
and re-provisioned due to the need to demolish the Yau Ma Tei Multi-storey Car
Park Building for construction of CKR.
To achieve this purpose, demolishing the section up to Temple Street is
considered sufficient. Moreover, the
structure crossing Nathan Road is a continuous concrete box girder balance
cantilever bridge from the Temple Street section, further demolishing the
section crossing Nathan Road is unnecessary.
Furthermore, demolition of the structure will lead to substantial
disruption to the traffic and the normal operation of the area.
The existing
GRF is a primary distributor (PD), which falls within the meaning of Item A.1
of Schedule 2, Part 1 of EIAO, i.e. a designated project defined under the EIA
Ordinance. Because of this change, the
environmental impacts arising are thus considered adverse with the factors listed
in Annex 3 of the EIAO-TM likely to cause the criteria in Annexes 4 to 10 be
violated, especially in traffic noise. The aforementioned re-provisioning of
the GRF is therefore considered a material change defined under S.6.1 (a) of
EIAO-TM.
The existing
GRF will tentatively be widened after commissioning of CKR. The widening of GRF
is a separate designated project and the EIA will be conducted according to the
Study Brief ESB-155/2006. Ultimately, this re-provisioned section of the GRF
will also be widened under the same package as the widening of GRF.
3.4.2
Re-alignment
of Hoi Wang Road
The section of
Hoi Wang Road between Lai Cheung Road and Yan Cheung Road is classified as
district distributor (DD) and falls within the meaning of Item A.1 of Schedule
2, Part 1 of EIAO, i.e. a designated project defined under the EIA Ordinance.
The existing Hoi Wang Road will need to be re-aligned because of the conflict
with the proposed western tunnel portal of the CKR. The Hoi Wang Road will be
re-aligned eastward with proposed slip roads connection with local roads.
Being an
exempted designated project, this substantial change in the physical alignment
constitutes a material change defined under S.6.1 (a) of EIAO-TM.
3.4.3
Widening of
Lai Cheung Road
Lai Cheung
Road needs to be widened to facilitate proper weaving arrangement and access to
the CKR network. Similarly, the section of Lai Cheung Road is a district
distributor (DD) and falls within the definition of Item A.1 of Schedule 2,
Part 1 of EIAO, i.e. a designated project defined under the EIA Ordinance.
Being an
exempted designated project, this substantial change in the physical alignment
constitutes a material change defined under S.6.1 (a) of EIAO-TM.
3.4.4
Gascoigne Road Flyover (Ferry Street Section)
The current carriageway width of the GRF
flyover is not in compliance with the design standard (Transport Planning and
Design Manual - TPDM). The reprovisioned
section of the GRF flyover under the CKR project will be designed in accordance
with the requirements of the TPDM, with a standard lane width of 4m and with a
1m wide marginal strip on either side. In addition to the standard lane width, where
the road is on a sharp curve the carriageway will be also widened in accordance with TPDM.
The resultant reprovided carriageways will be
wider and aligned differently at the interface with the existing section of
Gascoigne Road Flyover (Ferry Street Section), therefore the existing
carriageway lines will need to be realigned accordingly. In addition the realigned carriageways have
been checked for compliance with the sight distance requirements as specified
in the TPDM and it is found that widening of the marginal strip adjacent to the
central median and the edge parapets is required in order to provide a safe and
compliant design.
The extent of the affected section which
involves material change to the existing Gascoigne Road Flyover (Ferry Street
Section) will extend up to approximately 185m north of the interface with the
realigned section of Gascoigne Road Flyover (Kansu Street Section),
approximately in line with Tung Kun Street. Similarly, this section of Gascoigne Road Flyover (Ferry Street Section) is an urban
trunk road (UT) and falls within the definition of Item A.1 of Schedule 2, Part
1 of EIAO, i.e. a designated project defined under the EIA Ordinance.
Being an
exempted designated project, this substantial change in the physical alignment
constitutes a material change defined under S.6.1 (a) of EIAO-TM
3.4.5
Ferry Street
at-graded South Bound Slip Road
The current
Ferry Street at-graded south bound slip road is aligned around 1m offset from
the structure of the adjacent up-ramp slip road. It can only meet the minimum of 1m horizontal
clearance of TPDM's requirements for structure.
However, due to the proposed noise enclosure for Gascoigne Road Flyover (Ferry Street
Section), there is no space for the installation of the proposed noise
enclosure under the current road layout.
Hence, it is proposed to remove the existing Ferry Street Subway between
Ching Ping Street and at-grade slip road so as to provide space to align the
slip road. The scheme is to shift the
slip road toward east and the columns and foundations of the noise enclosure
will be put on the original position of the slip road. Similarly, this section of Ferry Street
at-graded south bound slip road is a primary distributor (PD) and falls within
the definition of Item A.1 of Schedule 2, Part 1 of EIAO, i.e. a designated
project defined under the EIA Ordinance.
Being an exempted
designated project, this substantial change in the physical alignment
constitutes a material change defined under S.6.1 (a) of EIAO-TM.
3.5
Proposed
Construction Methodology
3.5.1
Tunnel
Alignment Sections
Site-specific construction methodologies have been
developed comprising 4 different tunnelling methods, namely cut-and-cover
tunnel, drill-and-break tunnel, drill-and-blast tunnel and underwater tunnels.
Figure 3.1.1 to Figure 3.1.4 provides an overview of the CKR alignment.
With reference to the longitudinal and geological
profile of CKR, the cut-and-cover tunnels sections at both ends of the tunnel will
involve excavation of soil (fill) materials using non-percussive method while
the central portion of tunnel will be accomplished by the traditional
drill-and-blast (D&B) method within strata of the bedrock at more than 30 m
below ground.
A summary of the tentative construction methods for
the tunnel alignment is given in the table below. Detailed description of the
tunnelling methods can be referred the following sections.
Table 3.1: Summary of Tentative Construction methods
for the Tunnel Alignment
|
Section |
Form |
Tentative Construction Method |
Selection Reason |
|
Yau
Ma Tei (from Hoi Wang Road to Shanghai Street) |
Tunnel |
Cut-and-Cover |
· To facilitate connection between drill-and-break
tunnel and depressed road. |
|
Yau
Ma Tei (Shanghai Street to The Regalia) |
Tunnel |
Drill-and-Break
/ Drill-and-Blast Tunnel |
·
To
facilitate the geotechnical condition of the adjacent underground areas ·
To minimize
impact to adjacent public transport systems such as Tsuen Wan Line and the proposed
Kwun Tong Line Extension |
|
Ho
Man Tin, To Kwa Wan & Ma Tau Wai (The Regalia to San Ma Tau Street) |
Tunnel |
Drill-and-Blast |
· To facilitate the geotechnical condition of the
adjacent underground areas. |
|
Kowloon
City Ferry Pier Public Transport Interchange |
Tunnel |
Cut-and-Cover |
·
To
facilitate connection between drill-and- blast tunnel and underwater tunnel. |
|
Kowloon
Bay |
Tunnel |
Cut-and-Cover
with temporary reclamation |
· The only viable construction method
for underwater tunnel. |
|
Ex-Kai
Tak Runway |
Tunnel |
Cut-and-Cover |
·
To facilitate connection between underwater tunnel and the east end
tunnel portal before comes to the depressed road section. |
Yau Ma Tei
(from Hoi Wang Road to Shanghai Street)
‘Top-Down’ Cut-and-Cover method will be adopted for the shallow
section of tunnel in order to reduce the impact upon the surrounding area,
pedestrians and road traffic. The following paragraph explains
the 'Top-Down' Cut-and-Cover method.
Following completion of the diaphragm
walls, cross walls and the ground will be excavated to the tunnel roof
level and the tunnel roof slab constructed. This first stage of
excavation and roof slab works will be undertaken beneath temporary
decking. This decking provides a platform for pedestrian and road traffic
whilst also containing the noise and dust produced by the works being carried
out beneath. (An attenuation of minimum 20 dB(A) is envisaged for works
under the deck). Once the roof slab is complete, the area above the roof slab
is to be back-filled with the footpaths and the roads reinstated. The
remainder of the tunnel construction will then continue beneath the tunnel roof
slab. This approach has the advantage of allowing early reinstatement of
the roads and footpaths and therefore reducing the disturbance to the
public. Additionally, the roof slab and back-fill will provide
a barrier between the construction work of the lower part of the
tunnel and roads and footpaths at ground level (thereby improving the
noise and dust barrier temporarily provided by the temporary
decking). Conventional 'Bottom-Up' Cut-and-Cover construction would result in prolonged
use of the temporary traffic decking (this would increase the risk of adverse
effects of noise and dust at ground level) and would also delay the
reinstatement of the ground above the tunnel.
The construction of the cut-and-cover tunnel
will start from the west portion at the existing Highways Department's
maintenance depot at Yau Cheung Road. A tunnel access shaft located between
Shanghai Street and Battery Street will also be constructed at the early stage
for the construction of the tunnel in the central portion. In order to maintain
the traffic of the GRF and Kansu Street, diaphragm wall construction will be
undertaken in two phases. When the northern diaphragm wall is constructed, the
existing traffic at Kansu Street will be maintained. Whilst the southern side
diaphragm wall is under construction, Kansu Street will be temporarily
realigned north in order to provide sufficient working space.
The section of GRF be reconstructed is the
existing pre-cast composite viaduct between the Gascoigne Road
Flyover (Ferry Street
Section) and the balanced cantilever bridge crossing Nathan Road. A new viaduct
will be constructed along the north side of the existing GRF alignment. The
existing section of GRF will then be demolished. At the western end, the new
viaduct will connect to the existing carriageway of Gascoigne Road
Flyover (Ferry Street
Section) as well as utilising the existing end at YMT Police Station. The realignment of the existing Gascoigne
Road Flyover at Kansu Street would be constructed in phase, the east-west
traffic, i.e. dual-1 traffic lanes, will be maintained throughout the
construction period. It is noted that,
at this stage, the works at the demolished Yau Ma Tei Multi Storey Carpark will
involve the provision of temporary bridge structure to maintain the east-west
traffic. As for the constructions works between Kansu Street and Temple Street,
the east-west traffic will remain at the existing Gascoigne Road Flyover until
the works for the realignment works of Gascoigne Road Flyover is completed.
Dual-1 traffic lanes will be maintained throughout the construction period.
Yau Ma Tei
(Shanghai Street to The Regalia)
In the view of the
topography and geology of the Yau Ma Tei areas, drill-and-blast method will be
generally adopted for this section of the tunnel.
However, in certain locations such as public transport
system, the drill-and-break method (i.e. a non-blasting technique) will be
used. The drill-and-break method normally entails an alternative cyclic process
of drilling the tunnel face with small drills to form a “Swiss cheese”
structure in the rock, which can then be broken up using rock breakers. This
method will only be used when passing close to sensitive structures, where
blasting may be restricted.
As described in the previous section, the GRF will be
reconstructed between Ferry Street and Nathan Road. During construction, a series of temporary
viaducts will be constructed on and adjacent to the site of the existing Yau Ma Tei Multi Storey Carpark at junction
between Kansu Street and Temple Street. The temporary
viaducts will span over both Temple Street and Shanghai Street and will enable
a two way traffic to be maintained on the GRF whilst the multi storey car park
and Temple Street sections of the existing GRF are demolished and subsequently
replaced by the new GRF structure. The
new GRF will connect with the existing GRF cantilever span at the site of the
existing Hong Kong Automobile Association situated in between Temple Street and Nathan Road (NB
the existing GRF span above the Hong Kong
Automobile Association
will be retained).
Ho Man
Tin, To Kwa Wan & Ma Tau Wai (The Regalia to San Ma Tau Street)
In view of the topography and geology of the Ho Man
Tin, To Kwa Wan and Ma Tau Wai areas, the central portion of CKR mainly
comprises of a twin bored drill-and-blast tunnels in hard rock. The proposed
tunnels of about 2.8 km long would run in underlying rock strata below ground
to avoid affecting the buildings, roads and utilities at ground level.
The deep tunnels will be constructed by the
drill-and-blast (D&B) method. It is an economical method and less restricted
by site conditions and equipment set-up, where tunnelling by tunnel boring
machine (TBM) is not possible given the large diameters involved and the
extreme wear and tear expected due to the hard rock strata. The TBM method
entails using a TBM to bore through the ground to form a circular tunnel, which
is then lined with concrete, and is generally more suited to soft-ground
tunnelling, whereas the drill-and-blast method is more suited to hard-ground
tunnelling.
The main consideration in the choice is that the
diameter of tunnel should be large enough to accommodate at least 3 lanes for
each direction. This will require a minimum width of about 17m, which is
considered large for a tunnel. Hence, an
extremely large and powerful TBM would be required for CKR. Moreover, cutting
through hard rock could lead to excessive wear and tear in the cutter and
unnecessary over cut given the circular section produced by TBM.
For these reasons, tunnelling by TBM has been ruled
out due to considerations of the practicality. The drill-and-blast method is
considered most practicable and effective method for constructing the tunnel
section of CKR in central portion. This method is the traditional method for
boring through hard rocks, such as granite, and has been used successfully in
many previous road projects in Hong Kong. It entails a cyclic process of
drilling small holes into the tunnel face, filling the holes with explosives
and blasting the rock into smaller fragments to ease removal. Given that CKR is
located in an urban environment, the blasting will be strictly controlled to
minimise vibrations at the various buildings and structures above the tunnel.
Considering that duration of blasting will be very
short and be carried out underground and is infrequent in a day, as well as the
damping effect provided by the thick soft/fill materials underlying building
foundations, the airborne and ground-borne noise should unlikely be
significant.
To minimise the impact/ nuisances, it is considered
essential that blasting operations should not be carried out during sensitive
hours at close proximity to noise sensitive uses. Nevertheless, the
construction noise due to removal of debris of tunnelling will be part of the
construction noise assessment.
In certain locations, the drill-and-break method (i.e.
a non blasting technique) will be used. The drill-and-break method normally
entails an alternative cyclic process of drilling the tunnel face with small
drills to form a “Swiss cheese” structure in the rock, which can then be broken
up using rock breakers. This method is however laborious, and will only be used
when passing close to sensitive structures, where blasting may be restricted.
Kowloon
City Ferry Pier Public Transport Interchange
Similar to the Yau Ma Tei side, cut-and-cover (C&C) method will be adopted for the
tunnels located at the current Kowloon City Ferry Pier PTI at Ma Tau Kok where
trench is excavated and roofed over. In order to reduce impacts on the
environment and existing traffic, temporary decking will be constructed after
construction diaphragm wall and initial shallow excavation. The excavation
thereafter will be carried out under the temporary decking and removed at
certain mucking out point. After the completion of tunnel construction, the
ground level will be reinstated.
This method has the advantage of allowing early
reinstatement of the roads for the rearrangement of PTI and disturbance to
public can therefore be minimised. Further excavation are carried out under the
temporary decking away from direct impact on the public and hence provide a
shield to reduce the construction noise and fugitive dust.
The construction of the tunnel will be carried out in
phases such that the Kowloon City Ferry Pier PTI can be rearranged and kept in
function during the construction stage. A tunnel access shaft located at the
western side of the PTI will be constructed at the early stage for the
construction of the tunnel in central portion.
Kowloon Bay
A 370 m long section of the CKR tunnel
between the Kowloon City Ferry Pier to the Kai Tak Development Area will pass
through the seabed of Kowloon Bay. Due
to various site constraints, it will have to be constructed using the temporary
reclamation method.
We have considered whether the underwater
tunnel can be constructed using the following methods that would not involve
temporary reclamation –
(a)
Immersed Tube Tunnel (IMT); and
(b)
Tunnel Boring Machine (TBM).
(a) Immersed Tube Tunnel (IMT)
Under this method, a trench of about 220 m and
30 m deep will be excavated in the seabed along the tunnel alignment by
dredging of marine mud. The tunnel units (about 47 m to 58 m wide, and 16.5 m
high) will be cast off site and floated to the tunnel site for sinking into
pre-determined locations on the trench. The tunnel units will be joined. Upon
the completion of jointing, the trench will be backfilled to the original
seabed level.
The dredging of the trench for placement of
IMT box will involve the removal and disposal of approximately 0.75 million m3
of marine mud. Furthermore, as the sea in Kowloon Bay is only about 6m to 8m
deep, an approach channel of about 1,300 m long, 150 m wide and 12 m deep will
have to be formed adjacent to the tunnel site to provide sufficient draft for
floating the precast units thus resulting in the dredging and disposal of
approximately 1.8 million m3 of marine mud in total.
The trench will also affect the structural
integrity of the existing Ma Tau Kok and Kai Tak seawalls, and foundation of
the private buildings adjacent to the seawall. The jetty of Hong Kong China Gas
Co for transporting raw materials and the Kowloon City Ferry Pier would also
have to be relocated during the construction period.
Given the large volume of marine mud that
will have to be dredged to form the trench for placing the immersed tube units;
the equally large volume of marine mud to be dredged for forming the approach
channel for floating these units; and the impacts on the seawall, the adjacent
private buildings, the HKCG jetty and operation of passenger ferry, IMT is
therefore not a reasonable alternative.
(b) Tunnel
Boring Machine
This method involves boring of circular
tunnel section using Tunnel Boring Machine (TBM) through the stratum along the tunnel
alignment. The bored tunnel surface will
then be protected with concrete lining.
Before the construction of the concrete
lining, air pressure about 300 kPa to 500 kPa (or three to five times the atmospheric pressure) will have to
be applied inside the tunnel to uphold the excavated face of the tunnel and to
prevent the seepage of water into the tunnel. As such, sufficient soil cover
will be required for containing the pressure inside the tunnel. The amount of cover required will depend on
the ground conditions. Given the
relatively low strength (undrained shear strength
down to about 4kPa) of the soil in the seabed of Kowloon Bay the cover required will be
about 1.5 times the diameter of the tunnel.
The diameter of the eastbound tunnel (with three traffic lanes and one
climbing lane) will be 20.5 m. The diameter of the
westbound tunnel (with three traffic lanes) will be 17 m. The cover required will be about 30.75 m and
25.5 m respectively.
As the tunnel will
have to gradually rise to ground level to connect to the road network in Kowloon
Bay and KTD, the maximum soil cover will only be 17 m at the western end and
the minimum soil cover will only be 2 m at the eastern end. This will be less than 1.5 times the diameter
of the tunnel.
The available soil cover would be inadequate
for containing the air pressure that would be required for upholding the
excavated tunnel face and preventing the seepage of ground water thus leading
to blow out failure.
On the other hand, if the air pressure were
reduced, the pressure would be insufficient for upholding the excavated
sections and for preventing the seepage of ground water. As such, the tunnel could also fail because
of the collapse of the excavated face and excessive seepage of ground water.
For the foregoing reasons, the use of TBM for
constructing the underwater tunnel would be unsafe both for construction
personnel and the public. TBM is therefore not a reasonable alternative.
Construction
Method Involving Reclamation
Since both the IMT and TBM methods are not reasonable
alternatives, we have considered whether the underwater tunnel can be
constructed on temporary reclamation using the cut-and-cover method.
This method would require constructing pipe pile or similar wall system along either side of the underwater tunnel as temporary seawall and backfilling between them to create a dry working
platform such that the cut-and-cover tunnel may be constructed using the
diaphragm wall technique. This would be the safest construction method with
respect to both construction workers and local public. It would also enable
high-quality construction of the underwater tunnel.
The temporary seawall
structure is envisaged to consist of double-layer pipe pile wall, or a combined
wall type make up of pipe pile wall and sheetpile wall or similar to be installed to predetermined level. The double layer walls
are interconnected by diaphragm pipe pile wall or tie rod. The space between
the double layer walls will then be backfilled by suitable filling materials
for the completion of the temporary seawall structure. Prior to the
construction of the temporary seawall structure, ground treatment, such as
stone columns, will be carried out at the marine deposit layer to be left
in-situ in front or under the proposed temporary seawall structure to enhance
the stability of the seawall structure. As discussed in
Section 6.7.3,
the stone columns will be installed under seabed levels and a geotextile layers
will be installed to cover the seabed to prevent re-suspension and seabed
disturbance. A silt curtain will be deployed to the stone column working
vessels during penetrations.
After the completion of the
temporary seawall structure, reclamation will be carried out within the
temporary seawall to +4.0mPD to form a temporary working platform. A diaphragm
wall will then be constructed within the temporary working platform and the
subsequent excavation
and underwater tunnel construction works will
be carried out within the area enclosed by the temporary seawall by cut-and-cover method
with corresponding temporary lateral support system
After completion
of the underwater tunnel, the space above the tunnel box within the temporary
reclamation will be backfilled to the original seabed level while the temporary
lateral support system are being removed in phase. Demolition of the temporary
seawall will then take place. The proposed construction method adopts an
approach where the double-layer seawall will not be removed until completion of
all excavation works within the temporary reclamation area enclosed by the
double-layer seawall. The fill forming the temporary reclamation will be
removed and the diaphragm walls will be cut down to the original seabed level.
The double-layer seawall will then be demolished by first removing the soil
infill within the double-layer steel pipepile/sheetpile, followed by the
removal of the steel pipepile/sheetpile. The steel pipepile/sheetpile are
removed by full extraction from ground where possible, or otherwise trimmed to
just at the seabed level by underwater
cutting with no dredging of marine deposit involved.
The use of a 2-stage temporary reclamation rather than
having more stages is primarily due to the consideration of a tight construction
program as more stages need more interfacing works and will take more time
overall.
Additional merits of two stages of reclamation include
maintaining at all times a connection with the shore to enable timely and easy
access of plant, equipment and delivery of construction materials as well as
allowing direct removal of excavated materials. Having 3 or more stages will
simply create islands and is hence undesirable.
In brief, underwater tunnel by temporary reclamation
is considered technically feasible, safer and produce less contaminated or
uncontaminated sediment by dredging requiring open sea disposal.
Temporary Reclamation and Relation to Protection of the Harbour
Ordinance
The Protection of Harbour Ordinance (PHO) is not an
environmental legislation. However, it has the implications in relation to
reclamation in the Victoria Harbour. As
discussed above, temporary reclamation is required to facilitate construction
of the underwater tunnel in Kowloon Bay.
The PHO originally resulted from a private member’s
bill proposed in 1996 by the Society for Protection of the Harbour. The bill
was first enacted as the original Ordinance in June 1997 and was then modified
in the course of the legislative process. The PHO provides protection and
preservation of the harbour by establishing a presumption against reclamation.
In December 1999, the Ordinance was further amended to its present form by
expanding its scope to cover the whole of Victoria Harbour.
Section 3 of the Ordinance
states:
(1) The harbour
is to be protected and preserved as a special public asset and a natural
heritage of Hong Kong people and for that purpose there shall be a presumption
against reclamation in the harbour. [Section 3(1)]
(2) All public officers and public bodies
shall have regard to the principle stated in subsection (1) for guidance in the
exercise of any powers vested in them. [Section 3(2)]
On 27 February 2003 the Society for Protection of the
Harbour commenced legal proceedings and applied for judicial review of the
decisions of the Town Planning Board made in connection with the draft Wan Chai
North Outline Zoning Plan. Madam Justice Chu of the High Court delivered the
judgment on 8 July 2003 in respect of the judicial review. In the judgment,
with regard to the presumption against reclamation under section 3 of the
Protection of the Harbour Ordinance, the following three tests were laid down:
“...the purpose and extent of each proposed reclamation ought to be
individually assessed by reference to the three tests of –
·
Compelling, overriding
and present need;
·
No viable alternative;
and
·
Minimum impairment.”
The interpretation of the PHO ordinance deems that
reclamation works may only be considered justifiable if it satisfies the above
three tests. In view of this, a “Cogent and Convincing Materials Report for
Temporary Reclamation in Kowloon Bay” has been prepared to demonstrate
compliance with the overriding public need for CKR, setting out the findings of
the investigations and the conclusions regarding the need for reclamation and
the minimum extent of reclamation (see http://www.ckr-hyd.hk/pdf/044-02_English(Combined).pdf). To summarise, the need for CKR has been clearly
established through a series of traffic and transport studies which have taken
account of traffic growth and future development. The need for temporary reclamation to construct the
underwater tunnel portion of CKR is compelling as none of the potential
alternative alignment or construction ideas for the underwater tunnel have been
found to be feasible. The total area of temporary reclamation does not
exceed 3.8 ha, with a maximum of 2.0 ha at any given time.
Ex-Kai Tak Runway
Similar to the Kowloon
City Ferry Pier PTI, cut-and-cover (C&C) method will be adopted for the
tunnel box section located at the ex-Kai Tak Runway. It is a typical method of
construction frequently adopted for shallow tunnels where a trench is possible
to be excavated. The trench is excavated with lateral support system as
necessary, and the tunnel box is constructed inside. After the completion of
tunnel construction, the trench will be back-filled and the ground level will
be reinstated.
3.5.2
Yau Ma Tei
Interchange of the West Kowloon Highway and associated road network in West
Kowloon
The bridge form
is designed as continuous prestressed concrete box girder bridges which are
matched with the existing highway structures.
As the lengths of the bridge are relatively short, conventional
span-by-span method could provide more feasibility to suit different alignment
change of the bridges.
Typical span
length for intermediate span and end span is 50m and 40m respectively. 5.1m vertical clearance will be provided
between the bridge soffit and the underneath road surface. The width of the bridge for single traffic
lane (Bridge B2, B, C2, C and G) is 8.8m including edge planters. For the two traffic lane bridge (Bridge D),
the width will be increased to 12.1m.
Bored piles are
designed to transfer the loading from the bridge to the rock stratum. G.I. information indicates that the rock head
is located at around 55m below existing ground.
Retaining walls will
be provided at the locations where man-made slope is not feasible at the area
in close proximity with XRL vent building, new police station and the private
development site. L shape reinforced
concrete retaining wall type is designed for the retaining walls.
As the structural form of the elevated sections of the
connection roads in the Kai Tak Development and Kowloon Bay area is to be
designed as continuous prestressed concrete box girder bridges with relatively
short span length for flexibility to suit different alignment change and
various interface constraints, conventional cast in-situ span-by-span method is
to be implemented for construction of these bridges.
The construction methodology of the associated
underpass and at-grade sections of the connection roads will be in the form of
an open trench, with excavation (for below ground sections) and fill (for above
ground sections) in the Kowloon Bay area. All these features will be
constructed by cast in-situ method.
A landscaped
deck is designed to beautify the west end portal of CKR which is generally
following the vertical profile of CKR. The landscaped deck is a structure on
the cut-and-cover tunnel with green treatment for visual improvement. The primary function of the landscaped
deck is to serve as a noise enclosure to mitigate the potential noise nuisance on the adjacent sensitive
receivers.
The construction methodology of the landscaped deck
and the depressed road in the east portion will be in the form of an open
trench, with excavation in the Kai Tak area. Temporary shoring system with
water-proofing function will be used as external lateral support / cofferdam. The depressed road and landscaped deck
structures will be constructed by cast-insitu method. To resist uplift forces generated by the
maximum possible ground water level, tension piles will be adopted along the
depressed road section including the landscaped deck box structure.
For the landscaped deck on Kowloon City Ferry Pier
PTI, the structure is proposed to be in the form of reinforced concrete
structure supported by beams and columns. The reinforced concrete slabs and
walls of the PTI cover structure is designed for designed for no direct
line-of-sight of the noise sources at the noise sensitive uses in accordance to the
HKPSG.
3.5.5
Demolition and
/ or Re-provisioning Works
A number of government buildings and facilities may require decanting
and demolishing. A tentative list is give below. However, these decanting /
reprovisioning proposals are subject to review / change in the detailed design
stage.
|
Affected |
Decanting / Reprovisioning Requirement / Proposal |
Demolition Requirement |
|
YMT Police Station Old Wing: |
|
Retain |
|
Ø
Police |
Move to new police station |
|
|
YMT Police Station New Wing: |
|
Retain |
|
Ø
Police |
Move to new police station |
|
|
YMT Police Station Covered Car Port: |
|
Demolish |
|
Ø
Police |
Move to new police station |
|
|
YMT Police Station Kitchen and Laundry Block: |
Demolish |
|
|
Ø
Police |
- |
|
|
YMT Jockey Club Specialist
Clinic Extension Building: |
|
Demolish |
|
Ø
Methadone Clinic |
Move to Polyclinic Building site |
|
|
Ø
Maternal and Child Health Centre |
Further investigate the feasibility of
permanently reprovide within the proposed Community Health Centre at the
ex-Mon Kok Market site by Food and Health Bureau and Department of Health |
|
|
Ø
Dermatological Clinic |
Move to Polyclinic Building |
|
|
Ø
Other specialist clinics |
Move to new wing at Queen
Elizabeth Hospital |
|
|
YMT Multi-storey Car Park
Building (YMTCPB): |
|
Demolish |
|
Ø
Car park |
Demand taken up by other car
parks in the vicinity |
|
|
Ø
Government departments |
Temporarily moved to other
buildings and move to proposed West Kowloon Government Offices in long term |
|
|
Ø
YMT Public Library |
Relocate to the rest area at the
south of Henry G. Leong Yau Ma Tei Community Centre in construction phase and
relocate inside a new building to be constructed on the original site of the
YMTCPB |
|
|
YMT Jade Market: |
|
Demolish |
|
Ø
Jade market stall holders |
Move to temporary Jade Market and then to new Jade Market permanently |
|
|
Shanghai Street Playground and
Basketball Court |
|
Temporarily closed |
|
Ø
Recreational users |
Closed down temporarily and
re-opened after construction |
|
|
Ma Tau Kok Public Pier |
|
Demolish |
|
Ø
Passengers |
Move to temporary landing step
and then to new pier permanently |
|
Section of Gascoigne Road
Flyover
The tunnel portion of CKR will be constructed
underneath the foundation of Kansu Street section of GRF. The affected portion of the flyover will be
underpinned or re-constructed. In addition, the GRF (Ferry Street Section)
extending from Tung Kun Street to Kansu Street will be modified due to the
construction of CKR. Noise enclosures
and noise barriers will be installed at these to sections of flyover. Transparent materials and streamlined
structure will be adopted to enhance the appearance of the noise enclosures and
noise barriers. Greening will also be
provided at appropriate locations so that the noise enclosures and noise
barriers can better blend in with the surrounding environment.
A new bridge will be constructed on the north side
along the same GRF alignment and then demolished the existing section of the
flyover. At the west end, it will connect
to the existing carriageway of Gascoigne Road
Flyover (Ferry Street
Section) as well as utilizing the existing stub end at police station. On the east side, the new flyover will
connect at Temple Street with the balanced cantilever bridge crossing Nathan
Road. With the obstruction of the
Alhambra Building, it has to be built on the north side only.
To suit the nature of vary width of the new flyover,
cast in-situ pre-stressed concrete box girder bridge is considered as the most
appropriated structural form for the new flyover. As the alignment of CKR and GRF at that
section are overlapped, the new flyover will be stand on the top slab of the
CKR cut-and-cover tunnel.
Provisions for future widening to dual-two carriageway
will be allowed in the design of the deck as well as the piers and
foundations. The deck can be widened by
extending the cantilever slabs from the top slab. Noise enclosure will be provided at most of
the sections along the new flyover except the area facing Kansu Street CLP
substation building. At that section,
the noise barrier will be in the form of semi enclosure.
3.5.6
Conservation of
the Yau Ma Tei Police Station
Construction of CKR cut-and-cover tunnel underneath the
YMT Police Station New Wing Building will require to remove those affected
piles. An underpinning scheme is
required to transfer the existing column loadings to a deeper rock
stratum. The supporting system includes
cutting the existing ground floor slab to expose the existing pile caps and
then constructs transfer beams at both sides of the pile caps. The transfer beams will tie up with the
existing caps. Loadings of the transfer
beams will be transferred to the rock socket piles installed at the two ends of
the beams. As the existing building is
founded on pile, appropriate design of the underpinning work e.g. provide
sufficient clearance between the excavation trench and the existing piles, it is
anticipated that the structure of the building will not be jeopardised.
The existing old wing
building is a Grade II historic building built in 1920’s. The building is found on spread footing
foundation. CKR will allow 2.3m
clearance between CKR structure and the historic building. As a contingency measure, TAM grouting will
be carried out for the area around the building to control the settlement.
3.5.7
Ventilation Buildings and Administration Building
The West
Ventilation Building is proposed to be located adjacent to the existing FSD
Rescue Training Centre and will comprise one single integrated building. The building is proposed to have several
levels of basement with 3 storeys above ground level. At present it is perceived that the structure
will be in form of reinforced concrete and will be constructed by using
conventional cast-insitu method.
The proposed Ho
Man Tin Ventilation Building is proposed to be located adjacent to the existing
Ho Man Tin service reservoir and will comprise one single integrated
building. The building is proposed to
have several levels of basement with a some (to be determined) storeys above
ground level. At present it is perceived
that the structure will be in form of reinforced concrete and will be
constructed by using conventional cast-insitu method.
East Ventilation
Building and Administration Building are located near the existing Kai Tak
Tunnel. These 2 buildings can be
considered as one integrated building.
The building has several levels of basement with a few storeys exposed
above ground level. As there is not much
site and environmental constraints, the structure will be in form of reinforced
concrete and will be constructed by using conventional cast-insitu method.
Acoustic panels
will be fixed on the frame to provide sufficient sound insulation.
3.5.9
Temporary
Works Sites / Areas
There will be
temporary works sites / areas in the vicinity of the interchange structures,
tunnel, landscaped decks, depressed roads, ventilation buildings and
administration building to facilitate the construction process.
It is
recommended that C&D material should be transported off-site by barge
wherever possible to reduce impacts from road transport. There is a potential
barging point (being used by XRL project) at Kwai Chung underneath Cheung Tsing
Bridge. DLO/TW&KT has allocated the site until August 2015 to RDO/HyD. Figure 3.2.1
to Figure 3.2.12 show the
locations of these temporary works sites.