2.1.1
This section
presents a summary of the adopted alignment and preferred construction
methodology for the Project as well provides details of the alternative options
considered, and the constraints and considerations assessed in adopting the
preferred scheme and construction method.
2.2
Purpose and
Objective of the Project
2.2.1
TKO-LT Tunnel (which is the Project being considered
in this EIA Report), together with the proposed Trunk Road T2 (T2) in Kai Tak
Development (KTD) and Central Kowloon Route (CKR), will form Route 6 in the
strategic trunk road network (Figure 2.1).
2.2.2
As part of Route
6 and together with Cross Bay Link (CBL), the objective of the TKO-LT Tunnel is
to provide an east-west highway link between Kowloon and Tseung Kwan O (TKO)
areas.
2.2.3
In 2002, Civil Engineering and Development Department
(CEDD) commissioned an integrated planning and engineering study under
Agreement No. CE 87/2001 (CE), Further Development of Tseung Kwan O –
Feasibility Study (TKO Study), to formulate a comprehensive plan for the
further development of Tseung Kwan O (TKO). The TKO Study recommended that TKO
be developed further to house a total population of 450,000.
2.2.4
In March 2009, CEDD appointed AECOM Asia Co. Ltd.
(AACL) to carry out a detailed investigation study under Agreement No. CE
42/2008 (CE), Tseung Kwan O – Lam Tin Tunnel and Associated Works –
Investigation (the Assignment).
2.3.1
The Project
consists of six main sections:
1.
Roads P2/D4
Junction – this section comprises the footbridge connecting Park Central and
Area 74S DO site (namely Northern Footbridge), and the walkway linking it to
the grade separated cycle-track cum footpath connecting G/IC site at TKO Area
72, G/IC site at TKO Area 67 and Area 74S DO site (namely Southern Footbridge)
at Roads P2/D4 Junction.
2.
Landscape Deck at
Road P2 – this section comprises a depressed road section of Road P2 with
landscape deck at the eastern side of Ocean Shores was proposed to be designed
as DO site.
3.
Tseung Kwan O
Section (including TKO Interchange) – this section includes a straight
alignment with approximately 3ha of reclamation in Junk Bay for construction of
depressed Road P2 and
associated connection roads.
4.
Lam Tin Hill
Section – this section comprises the main tunnels and the branch tunnel about
90m and 67m below Kwong Ching House respectively.
5.
Lam Tin
Interchange – this section includes the link road connections between TKO-LT
Tunnel/T2, EHC and Cha Kwo Ling Road.
6.
Cha Kwo Ling Village
Section – this section comprises the tunnel alignment pass through the middle
of Cha Kwo Ling Village.
2.4.1
At present, the existing
TKO Tunnel is the main connection between TKO and the urban areas of Kowloon
and Hong Kong. However, it has nearly reached its capacity limit
due to further development of TKO. Thus, the existing TKO
Tunnel will hardly meet the anticipated future demand in terms of capacity,
convenience and level of comfort. The proposed new TKO-LT Tunnel together
with CBL will alleviate the frequent traffic congestion and meet the
long-term traffic demand between TKO and the external areas.
2.4.2
Traffic congestions have
already occurred during peak hours at TKO Tunnel. Its volume/capacity (v/c) ratio is around
1.14. According to the traffic impact
assessment carried out under Agreement No. CE 42/2008 (CE) Tseung Kwan O – Lam
Tin Tunnel and Associated Works – Investigation, it is envisaged that the
congestion during peak hours at TKO Tunnel would worsen, with the v/c ratio and
queue length (measured from toll plaza) of Kowloon-bound traffic during peak
hours reaching 1.38 and
Table 2.1 volume/ capacity (v/c)
ratio at existing TKO Tunnel
|
Year |
Anticipated
v/c ratios at TKO Tunnel during peak hours |
|
|
Without
TKO-LT Tunnel |
With
TKO-LT Tunnel |
|
|
2016 |
1.16 |
— |
|
2021 |
1.38 |
0.86 |
|
2026 |
1.38 |
0.88 |
Notes: volume/ capacity (v/c) ratio is an
indication of the traffic conditions of roads during peak hours. A v/c ratio equals to or less than 1.0 is
considered acceptable. A v/c ratio
between 1.0 and 1.2 indicates a manageable degree of congestion. A v/c ratio above 1.2 indicates more serious
congestion.
2.4.3
The legislative Council,
Sai Kung District Council and the local community have been urging for early
construction of TKO-LT Tunnel together with CBL such that these new roads will
provide the much needed additional transport capacity to meet the anticipated
future demand.
2.4.4
According to the traffic impact assessment for future
year carried out by the Project, capacity problem is anticipated to be experienced at the following key road links/junctions:
-
Kwun Tong Bypass (near Hoi
Bun Road)
-
Tseung Kwan O Tunnel
-
Clear Water Bay
Road (near Ying Yip Road)
-
Eastern Harbour Crossing
-
Hang Hau Road
-
Ying Yip Road
-
Po Lam Road (East of Sau Mau
Ping Road)
-
Ramp connecting Kwun Tong Bypass and Kai Fuk Road
-
Kai Cheung Road / Wang Chiu Road
-
Sheung Yee Road /
Wang Chiu Road
-
Kwun Tong Road/Hoi Yuen
Road/Hip Wo Street Roundabout
-
Cha Kwo Ling Road/Wai Yip
Street Junction
-
Lei Yue Mun Road / Tseung Kwan O Road
-
Lei Yue Mun Road/Kai Tin Road Roundabout
-
Cha Kwo Ling Road/Ko Fai Road Junction
-
Po Lam Road North/Po Hong
Road Junction
-
Po Lam Road North/Tsui Lam
Road Junction
-
Po Lam Road North/Lam Shing
Road Junction
-
Ying Yip Road/Po Ning Road/Sheung Ning Road Roundabout
-
Clear Water Bay Road/Hang
Hau Road/Yip Yip Road Roundabout
-
Wan Po Road /Po Yap Road /
Chiu Shun Road
-
Po Yap Road /Tong Yin
Street / (Future Road L671)
-
Po Yap Road /Tong Chun
Street / (Future Road L661)
-
Wan Po Road/Pak Shing Kok Access Junction
-
Wan Po Road / LOHAS Park Road
-
Wan Po Road / Shek Kok Road
2.4.5
Based on the results of traffic impact assessment, the
existing road network in Kowloon East and Tseung Kwan O area will experience
serious congestion if an alternative external road link is not provided to meet
the population growth and the continuing commercial and industrial development
in the TKO area.
Scenario with
the Project
2.4.6
Upon the completion of TKO-LT Tunnel, capacity problem on traffic flow in the following
locations will be eased or even resolved:
-
Tseung Kwan O Tunnel
-
Clear Water Bay Road (near Ying Yip Road)
-
Hang Hau Road
-
Po Lam Road (East of Sau
Mau Ping Road)
-
Kai Cheung Road / Wang Chiu Road
-
Kwun Tong Road/Hoi Yuen
Road/Hip Wo Street Roundabout
-
Lei Yue Mun Road / Tseung Kwan O Road
-
Po Lam Road North/Po Hong
Road Junction
-
Po Lam Road North/Tsui Lam
Road Junction
-
Po Lam Road North/Lam Shing
Road Junction
-
Ying Yip Road/Po Ning Road/Sheung Ning Road Roundabout
-
Clear Water Bay Road/Hang
Hau Road/Yip Yip Road Roundabout
-
Wan Po Road /Po Yap Road /
Chiu Shun Road
-
Wan Po Road/Pak Shing Kok Access Junction
-
Wan Po Road / Lohas
Park Road
-
Wan Po Road / Shek Kok Road
2.4.7
The effects of TKO-LT Tunnel on journey times and queue lengths have also been examined and the
results are summarised in Table 2.2 and Table 2.3. It is concluded from the results of the study that the presence of
TKO-LT Tunnel will significantly improve traffic conditions by reducing both
journey times and queue lengths.
Table 2.2 Improvements to Journey
Time by TKO-LT Tunnel
|
From |
To |
Journey Time |
|
|
2011 - Existing Route |
2021 - Using TKO-LT Tunnel (and Route 6) |
||
|
Junction of Yau Tong Road/ Cha Kwo Ling Road |
End of CKR at Yau Ma Tei |
22 mins.(1) |
8 mins.(2) |
|
Junction of Po Yap Road /Po Shun Road |
EHC |
12 mins.(3) |
3 mins.(4) |
|
Junction of Po Yap Road /Po Shun Road |
End of CKR at Yau Ma Tei |
30 mins.(5) |
12 mins.(6) |
|
Junction of Wan Po Road /Wan O Road |
End of CKR at Yau Ma Tei |
35 mins.(7) |
15 mins.(8) |
(2) Journey
route: Cha Kwo Ling Road, Cha Kwo Ling Roundabout, Trunk Road T2 and CKR.
(3) Journey route:
Po Shun Road, Tseung Kwan O Tunnel, Tseung Kwan O Road and Lei Yue Mun Road.
(4) Journey route:
Road P2, Tseung Kwan O – Lam Tin Tunnel
(5) Journey route:
Po Shun Road, Tseung Kwan O Tunnel, Tseung Kwan O Road, Kwun Tong Bypass, Kai
Fuk Road, Kai Tak Tunnel, East Kowloon Corridor, Chatham Road North and
Gascoigne Road.
(6) Journey route:
Road P2, Tseung Kwan O –
Lam Tin Tunnel, Trunk Road T2 and CKR.
(7) Journey route:
Wan O Road, Tseung Kwan O Tunnel, Tseung Kwan O Road, Kwun Tong Bypass, Kai Fuk
Road, Kai Tak Road, East Kowloon Corridor, Chatham Road North and Gascoigne
Road.
(8) Journey route:
Cross Bay Link, Tseung Kwan O – Lam Tin Tunnel, Trunk Road T2 and CKR.
Table 2.3 Improvements to Queue Length by TKO-LT Tunnel
|
Location |
Queue Length from Toll Plaza |
||
|
2011 - Existing
Road Network |
2018 - Without TKO-LT Tunnel (and Route 6) |
2018 - With TKO-LT Tunnel (and Route 6) |
|
|
TKO Tunnel (Westbound) |
2km |
2.9km |
0.05km |
2.4.8
According to the
traffic improvement proposals under this TKO – LT Tunnel and associated works,
all the existing public transport facilities including bus, GMB, RMB, taxi and
ferry will be retained. As such, there
will not be any adverse impact on these provisions. On the contrary, this
project will provide new roads and junction improvements thereby resulting in
improvements to the existing public transport network.
2.5
Benefit of the Project
2.5.1
Traffic congestion is now common on many of the
existing east-west surface routes such as Boundary Street, Prince Edward Road,
Kwun Tong Bypass, TKO Tunnel. A new
east-west traffic route is required to bypass theses areas which accommodated a
large portion of residential premises and connect West Kowloon directly with
Kowloon Bay, Yau Tong and Tseung Kwan O and thereby relieving the traffic
congestion on these roads. Upon
completion of Route 6, an alternative east-west traffic route across Kowloon
will be provided to cope with new developments on its western and eastern
sides. The new road network will relieve
the existing heavily trafficked road network in central and eastern Kowloon
areas and hence reduce journey time and numbers for vehicles across these areas
and the associated environmental impact particular air quality and noise impact
generated from vehicles.
2.5.2
With the presence
of TKO-LT Tunnel and associated works, some of the traffic will be attracted to
use TKO-LT tunnel. Traffic loading on Kwun Tong Bypass, Lei Yue Mun Road, TKO
Tunnel Road and Wan Po Road will be reduced and the environmental impact due to
traffic at these locations will also be reduced.
2.5.3
In addition, with the spare capacity of TKO Road resulting from the
commissioning of TKO-LT Tunnel, TKO Road can cope with the future developments
in Kwun Tong district, including the proposed housing development in the
vicinity of Anderson Road.
2.5.4
After commissioning TKO-LT Tunnel and CBL, heavy trucks heading to TKO
Area 137 from TKO Tunnel and Wan Po Road’s section between TKO Tunnel and Lohas
Park which is adjacent to the densely populated area in TKO(S) will be diverted
to TKO-LT Tunnel and CBL instead. Hence,
the environmental impact created from the heavy trucks to TKO(S) shall be
reduced.
2.6
Scope of the Project
2.6.1
The outlined scope of the Project under this Assignment is
to provide a highway connecting TKO at Po Shun Road in the east and Trunk Road
T2 in the west with the associated interchange.
The project layout plan is shown in Figure
2.2. It comprises the following:
(a)
a dual
two-lane highway approximately 4.8 km long.
About 2.6 km of the highway is in the form of tunnel;
(b)
slip
roads, depressed roads, viaducts, TKO Interchange, ventilation building, tunnel
portal facilities and around 3 ha reclamation on TKO side;
(c)
slip
roads, branch Tunnels, viaducts, Lam Tin Interchange, tunnel portal facilities,
ventilation and administration buildings; and
(d)
the
associated building, civil, structural, marine, electrical and mechanical,
traffic control and surveillance system (TCSS), landscaping, and environmental
protection and mitigation works.
2.6.2
Figure 2.2 shows the Location, boundary and general layout of the Project. The tunnel
facilities layouts of the TKO-LT tunnel are shown on Appendix 2.7.
2.7
Consideration of Alternative Options
2.7.1
The design of the Project has undergone a detailed
evaluation of different alignments and form of structures to arrive at the
optimum planning, engineering and environmental solutions which fit together in
a coherent manner. The following sections summarises the evaluation criteria
and the consideration of various alternative options.
Criteria
for Options Development
2.7.2
To assess the suitability of the alternative options
for TKO-LT Tunnel, a range of environmental, engineering, planning and general
community disruption considerations were developed for the decision making
process. Table 2.4 presents the
evaluation criteria and associated key issues and constraints for the options
selection process.
Table 2.4 Evaluation
Criteria and Associated Key Issues and Constraints
|
Criteria |
Associated Key Issues and
Constraints |
|
Transport and Operation
Planning |
· Connectivity
at Lam Tin – options that provide the direct slip
road connection between TKO-LT Tunnel, T2, Eastern Harbour Crossing (EHC) and
Cha Kwo Ling Road will be considered more desirable. · Traffic impacts
on local road network - Options that will not overload the
local road network due to absence of some slip road connections will
be considered more desirable. · Utilization
of existing TKO Tunnel – options that will deteriorate the
utilization of TKO Tunnel after commissioning of TKO-LT Tunnel will be
considered less desirable. · Utilization of
new TKO-LT Tunnel and associated slip roads – Options that
will not under-utilize / over-utilize the new TKO-LT Tunnel and associated
slip roads will be considered more desirable. · Tunnel
and toll plaza – options that will not deteriorate the
management, operation and maintenance of tunnel and toll plaza will be
considered more desirable. Those options that provide adequate merging length
before portal are considered more desirable. Options that can provide bus-bus
interchange and the associated pedestrian connections at the toll plaza will
be considered more desirable. · Development
access – options that provide connections to
TKO Town Centre South and the proposed vehicular road connecting the Junk Bay
Chinese Permanent Cemetery will be considered more desirable. · Travel
distance – options that provide more direct
routes will be considered more desirable. · Alignment
design – options with ‘desirable’ design
standard for both horizontal and vertical alignment design will be considered
desirable whilst those options falling below the ‘desirable’ standards are
considered less desirable. Those options only achieving ‘absolute’ design
standard will be considered undesirable whilst those options falling below
the ‘absolute’ design standard are unacceptable. · Tunnel
length – options with “excessively” long
lengths of tunnel will be considered less desirable. · Weaving
arrangement – options with adequate weaving
distances before and after the tunnel respectively will be considered
desirable. Those options with weaving distances shorter than the ‘minimum’
weaving length or weaving section falling within the tunnel will be considered
undesirable. As related issue, the directional signage strategy will be
considered together the weaving arrangement through the exercise. · Reclamation
for toll plaza – Options with the least reclamation and
disturbance to the marine ecology and fisheries are more desirable. |
|
Engineering Issues |
· Interface
with T2 – options that change the T2 alignment,
on the other hand, options that affect the traffic management of T2 tunnel,
will be considered less desirable. · Interface
with CBL – options that change the alignment of CBL
and hence increase the extent of reclamation required to protect the mainline
and slip roads will be considered less desirable. · Utilities
– options that require diversion of any major utility will be considered less
desirable. · Road safety – options
that create significant increases in traffic impacts in both the
operation and construction stages will be considered less desirable. · Highway infrastructure – options that cause the greatest
permanent impact on existing highway infrastructure will be considered less
desirable. · Geotechnical
and Geological conditions – providing geotechnical and geological risks are
assessed as acceptable, the option with less adverse conditions will be
considered more desirable. · Tunnel
construction – options without significant
construction risks by using drill and blast or TBM, reasonable construction
cost and time will be considered more desirable. · Viaduct
foundation – options with foundation on difficult
ground will be considered less desirable. · Natural
terrain hazards – options will be assessed based on the
presence of significant landslide, debris flow and boulder/rockfall hazards
and will be avoided where possible. · Waterworks
Installations – options that cause the least impact on
existing waterworks installations and water mains will be considered more
desirable. |
|
Planning
and Lands Issues |
· Land
resumption (private) – options with fewer potential land
resumption problems (e.g. Cha Kwo Ling Village) will be considered more
desirable. · Land
clearance (STT/GLA) – options with fewer potential land
clearance problems will be considered more desirable. · Government
and community facilities – options that impact on Government and
community facilities (e.g. Lam Tin Ambulance Depot) will be considered less
desirable. · East
Harbour Crossing – options that impact on EHC tunnel area
and associated facilities will be considered less desirable. · Committed
Development – options that impact in the committed
development (e.g. the Yau Tong Bay comprehensive
redevelopment) will be considered less desirable. ·
Development Potential of “Residential (Group A)
4” (“R(A)4” Zone at Cha Kwo Ling Village (CKLV) –
options that will have less impact on the development potential of “R(A)4”
zone will be more desirable. |
|
Environmental
Impacts |
· Marine
Ecology – options involving no / the least
reclamation, loss of natural shoreline and causing the least effects on
species of conservation interest, such as the Philippine Neon Goby, Grass
Puffer fish, coral communities and their habitats and fewer potential impacts
to other marine ecological resources will be more desirable. · Fisheries
– options with the least reclamation and reduced
fishing ground loss and causing the least disturbance to fishing operations
and fisheries resources will be more desirable. · Water
quality/flows – options causing the least impact on
water quality and hydrodynamics will be more desirable. · Air
and noise – options with fewer potential noise and
air quality impacts during both the construction and operational phases will
be more desirable. · Landfill
gas – options causing the least impact on
landfill gas and leachate hazards generated from the Sai Tso Wan landfill
will be more desirable. · Waste
management – options which generate the least amount
of disposal materials will be more desirable. · Landscape
and visual – options which result in the least
landscape and visual impacts will be more desirable. · Archaeology
– options
which result in the least terrestrial and marine archaeological impacts will
be more desirable. · Built Heritage – options that cause the least impact on the built
heritages, such as the Tin Hau Temple, Four Hills Public School, Law Mansion
in the CKLV area, will be considered more desirable. |
|
Sustainability
and Social Impacts |
·
Social
impact to public and affected individuals – options with the least or no social impacts
during the planning/design, construction and operation stages will be
considered more desirable. |
|
Public
Perception |
·
Previous
consultation – options that
will be in conflict with the comments and concerns raised in previous
consultations during the feasibility stage of the project will be considered
less desirable. |
|
Costs,
Implementation and Programme |
· Capital cost – options that the tunnelling methods and the
construction methods relating to massive dredging and reclamation works
associated with high cost will be considered less desirable. · Recurrent consequences – options that require high annual recurrent
costs for repair and maintenance, energy and staff will be considered less
desirable. · Implementation programme – options that implementation programme will be
influenced by the difficulties of the construction method, complexity of the
departmental procedures and the diversion of the existing utilities, is
considered less desirable. |
2.7.3 Throughout the
formulation of the preferred option, a series of public consultation/engagement
activities was held to gather comments and recommendations from public on the
Project, including alignment selection, form of construction, land intake, environmental impact, traffic impact and
engineering issues, as well as preservation of local culture and heritage, land-use
planning and social impact. The activities include meetings, presentations and
focus group meetings/forums with key stakeholders such as, local
representatives, professional institutions, community groups,
conservation/green groups, trade and industrial association related to, public
transport, industrial, and various services providers and relevant government
departments/ statutory bodies etc. Table 2.5 summarises the
activities during the public consultation process.
Table 2.5 Summary of Public Consultation/Engagement Activities
|
Date |
Consultation/Engagement
Activity |
|
Stage
1 Public Engagement |
|
|
7 April 2009 |
Briefing to concerned members of Sai Kung
District Council (SKDC) |
|
21 May 2009 |
Briefing to concerned members of Kwun
Tong District Council (KTDC) |
|
6 June 2009 |
1st stage Focus Group Meeting
(FGM) with green groups and professional institutes |
|
11 June 2009 |
1st stage FGM with AC members,
estates and Owners’ Committee members
in the vicinity of the project in TKO(S) |
|
18 June 2009 |
1st stage FGM with AC members,
estates and Owners’ Committee members
in the vicinity of the project of Kwun Tong and Lam Tin and Cha Kwo Ling
Village (CKLV) representatives |
|
Stage
2 Public Engagement – Kwun Tong Area |
|
|
27 May 2010 |
KTDC T&TC meeting |
|
10 June 2010 |
Informal meeting with Cha Kwo Ling
Village Representatives and the concerned DC member |
|
22 June 2010 |
Public Engagement Workshop
with KT & LT residents’ representatives |
|
6 July 2010 |
KTDC meeting |
|
25 July 2010 |
Meeting with the residents of Yau Lai
Estate including the concerned DC member |
|
27 July 2010 |
Meeting with Cha Kwo Ling villagers |
|
20
August 2010 |
Lam Tin interchange models display at of
Yau Lai Estate for the residents (I) |
|
26 September 2010 |
Lam Tin interchange models display at of Yau Lai
Estate for the residents (II) |
|
3 October 2010 |
Consultation of Lam Tin Hill section |
|
Stage 2 Public Engagement – Tseung Kwan O
Area |
|
|
11 November 2009 |
Meeting with Park Central representatives |
|
14 November 2009 |
Meeting with Ocean Shores representatives |
|
17 November 2009 |
Meeting with SKDC |
|
3 September 2010 |
Meeting with representatives
from Owners’ Committee of Ocean Shores |
|
7 September 2010 |
SKDC meeting |
|
11 September 2010 |
Stage 2 Focus Group Meeting with green groups and professional
institutes |
|
21 September 2010 |
Public Engagement Workshop
with TKO residents |
|
Stage 3 Public Engagement – Kwun Tong
Area |
|
|
2
Feb 2012 |
KTDC
meeting |
|
11
Feb 2012 |
Public Forum for TKO-LT Tunnel |
|
21
Feb 2012 |
Consultation
meeting for Kwong Tin Estate, Hong Pak Court, Hong Nga Court |
|
22
Feb 2012 |
Consultation meeting for Cha Kwo Ling (CKL) Village |
|
25
Feb 2012 |
Consultation meeting for Yau Lai Estate |
|
15,
20-22, 27-29 Apr 2012 (three consecutive weekends) |
Exhibition
at Yau Lai Estate to display the physical model of Lam Tin Interchange |
|
9
May 2012 |
Lam
Tin Area Committee (AC) meeting |
|
25
May 2012 |
Kwun
Tong South (AC) meeting |
|
Stage
3 Public Engagement – Tseung Kwan O Area |
|
|
12 Feb 2012 |
Public Forum for TKO-LT Tunnel and CBL |
|
27
Apr 2012 |
Consultation meeting with Ocean Shores |
2.7.3.1
Key
views received during the public consultation/engagement activities are
summarized in Table 2.6.
Table 2.6 Summary of
Public’s Views Collected during the Consultation Process
|
|
Major Views/Comments |
|
Stage 1 Public Engagement |
·
To ensure cost effectiveness and
sustainability of the project. ·
To preserve the existing natural
shorelines along the western coast of Junk Bay as far as practicable. ·
To reduce the scale of reclamation
as far as practicable taking into consideration different tolling system and
different layout for the toll plaza. ·
To adopt appropriate noise barriers
or mitigation measures addressing the noise generated from the highway. In
particular for estates near the portals. ·
To address the environmental
impacts, particularly implications on the marine ecology at Junk Bay. ·
To preserve the integrity of Cha
Kwo Ling Village and minimize construction impact. ·
To address the traffic problem on
local roads during construction of the project. ·
Welcome the provision of a
cycle-track loop in Tseung Kwan O for leisure/transportation usage. Some also
opined that if the cycle-track loop could cater for competition to take
place, it would be an added-value to the project. |
|
Stage 2 Public Engagement – Kwun Tong Area |
·
To ensure cost effectiveness and
sustainability of the project. ·
To ensure minimal nuisance to the
public during and after construction. ·
To carry out more informal meetings
and/or consultation to the public. ·
To adopt appropriate noise barriers
or mitigation measures addressing the noise generated from the highway. In
particular for estates near the portals. ·
To address the environmental
impacts, particularly noise and air pollution and light effect. ·
To preserve the integrity of Cha
Kwo Ling Village and minimize construction impact. ·
To address the traffic problem on
local roads during and after construction of the project. ·
To concern on redevelopment right
for creation of easement at underground stratum of private lots. |
|
Stage 2 Public Engagement – Tseung Kwan O Area |
·
To ensure cost effectiveness and
sustainability of the project. ·
To reduce the extent of reclamation
and preserve the existing natural shoreline ·
To avoid/minimize nuisance/impact
to the public during and after construction. ·
To carry out more consultation
meetings with the public. ·
To adopt appropriate noise barriers
or mitigation measures addressing the noise generated from the highway, in
particular for estates near the portals. ·
To address the environmental
impacts, particularly noise and air pollution to Ocean Shores. ·
To address the traffic problem on
local roads during and after construction of the project. ·
To further improve the slip roads
of TKO interchange in order to minimize the noise and visual impacts to
nearby residents such as Ocean Shores. ·
To further study the feasibility of
bus-bus interchange at Po Yap Road. |
|
Stage 3 Public Engagement – Kwun Tong and Tseung
Kwan O Area |
·
To implement the project as soon as
possible ·
To minimize the nuisance to the public during and after
construction (including tunnelling work under existing building structures). ·
To implement appropriate mitigation
measure to alleviate the environmental impacts included by the project
including noise, air quality, light and visual impacts. ·
To consider if further mitigation
measures can be provided at Lam Tin Interchange to further reduce the
environmental impacts, particularly noise and air pollution and light effect
to Yau Lai Estate. ·
To preserve CKL Village and
avoid/minimize nuisance/impact during construction. ·
To address the traffic problem on
local roads during and after construction of the project. ·
To try avoiding the tunnel to pass
underneath the existing buildings ·
To enhance
greening measures upon the landscape deck near Ocean Shores. |
2.7.4
These received views have been taken consideration in
the alignment studies. Having received concerns/views/ understanding via the
public consultation/engagement, feasible alignment and design options have been
developed accordingly. These feasible alignment and design options have been
brought forward for discussion with key stakeholders to seek their views on the
feasible alignment and design options throughout the consultation process.
2.7.5
Following the Stage 2 public engagement, the
recommended scheme was formulated taking into account of the engineering study
and comments received from the public engagement. The Recommended scheme was endorsed in
December 2010 and presented before the public during the Stage 3 public engagement.
2.7.6
Taking into account of public views collected in the 3
stages of public engagements, environmental factors and engineering
considerations, an optimum preliminary design of TKO-LT Tunnel has been
developed. Consultation with Sai Kung
and Kwun Tong District Council was conducted in January 2013. Both supported TKO-LT Tunnel and CBL and
urged for its early implementation.
Review
of Previous Options
2.7.7
A review of the previous options for TKO-LT Tunnel in
the preceding feasibility study assignments is presented in the following
sections.
Feasibility
Study on Alternative Alignment for the Western Coast Road
2.7.8
At present, TKO Tunnel is the main external road link
between TKO and other areas in the Territory. It will be saturated as a result
of the continual development of TKO, and a new external road link is necessary.
Under the “Tseung Kwan O Feasibility Study of Opportunities for Further
Development” (1990), the need for improved transport infrastructure was
identified in the form of a new dual 3-lane highway named the Western Coast
Road (WCR), which would link Cha Kwo Ling Road (CKLR) in East Kowloon to Po
Shun Road in TKO. A Preliminary Project Feasibility Study for WCR was completed
in 1995.
2.7.9
Subsequently, the TKO population growth was revised,
and the “Feasibility Study on Alternative Alignment for the Western Coast Road”
(Agreement No. CE 46/96) recommended a new dual 3/4-lane highway linking East
Kowloon with TKO via an alignment on reclamation along the coastline in TKO and
Lei Yue Mun.
2.7.10
A review was undertaken of the WCR coastal alignment
and the refinements were presented in the subsequent “Study on Minimization of
the Impacts of Western Coast Road on Lei Yue Mun Village” (Agreement No. NTE
5/99). The coastal alignment option was modified to dual 2-lane configuration
together with refinement of arrangements for connections at TKO and Kowloon.
Preliminary Feasibility Study on Tunnel Alignment
Option of Tseung Kwan O Western Coast Road
2.7.11
As a result of considerable public opposition to the
proposed coastal alignment were received, “Preliminary Feasibility Study on
Tunnel Alignment Option of Tseung Kwan O Western Coast Road” (Agreement No. NTE
1/2000) was commissioned in 2000 to examine and develop a viable tunnel option
between East Kowloon and TKO.
2.7.12
The above study identified eight “western” tunnel
alignment options and five “eastern” tunnel alignment options, as shown in Figure 2.3. After a preliminary
assessment process, three tunnel alignment options, namely Options 1, 2 and 3,
as shown in Figure 2.4 and
summarised below, were selected for more detailed assessment:
·
Option
1 comprised a longer northern tunnel that avoided the Yau Tong Bay area and
passed under the Eastern Harbour Crossing (EHC) and out to at-grade highway in
the old quarry before passing under the site of the former kaolin mine and into
cut-and-cover tunnel prior to connecting to T2.
·
Option
2 had the same horizontal alignment as Option 1, but did not pass under the
EHC. Instead, the tunnel emerged from the hillside onto viaduct that passed
over Lei Yue Mun Road (LYMR) and the EHC and down into the old quarry, before
passing under the site of the former kaolin mine and into cut-and-cover tunnel
prior to connecting to T2.
·
Option
3 comprised a shorter southern tunnel that passed in cut-and-cover tunnel
through the Yau Tong Bay area north of Lei Yue Mun Village. An at-grade highway
then passed around Yau Tong Bay and out over the sea on viaduct before
connecting to T2.
2.7.13
The northern
alignments of Options 1 and 2 were found to have clear advantages over the
southern alignment of Option 3, particularly with respect to land and
environmental impacts. Option 1 was duly selected as the preferred tunnel
alignment option.
2.7.14
The above study
then compared the preferred tunnel alignment option with the original proposed
coastal alignment option against various categories of relevant criteria. The
tunnel alignment option was found to have advantages over the coastal alignment
option on environmental, planning and transport, engineering and programme
grounds. The study duly recommended the tunnel alignment option as the
preferred scheme for the WCR.
Further Development of Tseung Kwan O – Feasibility
Study
2.7.15
In 2002, CEDD
commissioned the “TKO Study” to formulate a comprehensive plan for the further
development of TKO. In the TKO Study, the long-term transport need of TKO was
examined and the need for a new road network comprising WCR, CBL and Road P2
was identified.
2.7.16
Two main
alignment options for the WCR were examined under the TKO Study, namely the
“tunnel alignment” and the “coastal alignment”. The tunnel alignment option was
developed and refined, taking account of the need mainly to:
·
provide
improved connectivity at both the Kowloon and TKO sides;
·
provide
direct connections with the EHC;
·
provide
tunnel facilities (i.e. administration and ventilation buildings, recovery
areas, etc);
·
provide
a toll plaza; and
·
minimise
construction interfaces with existing and planned infrastructure/ development.
2.7.17
The study
identified four possible locations for the toll plaza at the TKO side, as shown
in Figures 2.5 to 2.6. The public
and green groups have requested to preserve the natural shoreline at the
Eastern Portal. One option, Scheme 5, as shown in Figure 2.7 presents the alignment without toll plaza. No
reclamation would be required for this option. Therefore, the effect on the
ecological and fisheries resources including the natural shoreline and species
of conservation interest, such as coral and Philippine Neon Goby, would be
minimised. After a preliminary assessment process, two options, namely Schemes
1 and 3 and subsequently renamed as Schemes A and B, as shown in Figure 2.8 and summarised below, were
selected for more detailed assessment:
·
Scheme
A comprised a toll plaza on proposed reclamation projecting out from the
coastline below the original proposed eastern tunnel portal. In order to
provide adequate space for the toll plaza, the WCR/CBL/Road P2 interchange was
reconfigured as a trumpet interchange and the alignment of Road P2 was shifted
eastward to suit the location of the new interchange.
·
Scheme
B comprised a toll plaza on proposed reclamation running parallel with the
coastline. To accommodate this arrangement, the eastern tunnel portal was
relocated southwards and the tunnel realigned at the TKO side to suit. This
arrangement increased the length of the tunnel, but reduced the size of the
WCR/CBL/Road P2 interchange.
2.7.18
Scheme B was
found to have advantages over Scheme A, particularly with respect to
environmental impacts and engineering and traffic considerations. Scheme B was
duly selected as the preferred tunnel alignment.
2.7.19
The coastal
alignment was also developed and refined, taking account of the need mainly to:
·
update
the design based on the latest design standards;
·
provide
improved connectivity at both the Kowloon and TKO sides;
·
provide
for a potential toll plaza (although not a tunnel);
·
minimise
the impacts of the alignment on Lei Yue Mun Village.
2.7.20
The refined
coastal alignment, as shown in Figure
2.9, ran from T2 and passed south of the EHC and across Yau Tong Bay,
through the previously proposed reclamation along the Yau Tong waterfront,
before crossing over the entrance to Sam Ka Tsuen Typhoon Shelter on viaduct.
It then turned around the hillside at Lei Yu Mun Point and crossed the coastal
waters on viaduct before passing onto proposed reclamation along the TKO
western shoreline and connecting with CBL and Road P2.
2.7.21
After public
consultation and technical evaluation, the tunnel alignment was endorsed. WCR
was thus renamed as the “Tseung Kwan O – Lam Tin Tunnel (TKO-LT Tunnel)”. Under the TKO Study, the engineering feasibility of
TKO-LT Tunnel was established and endorsed. This scheme is covered by a
Schedule 3 EIA Report completed for the TKO Study. It was approved without
conditions on 8 December 2005 (Register No.: AEIAR-092/2005).
2.7.22
Under the
approved scheme, the Kowloon Section of TKO-LT Tunnel (i.e. the section of
trunk road between the western tunnel portal at Lam Tin and T2) passed through
a housing development at the former site of the kaolin mine at Cha Kwo Ling.
The road formation for the trunk road and local road connections would be
completed by the housing development. After passing through the housing
development, the trunk road would connect to the proposed T2, which was planned
to be on viaduct at that time.
Alternative Arrangements of TKO-LT Tunnel
at Kowloon Side
2.7.23
Subsequently
under the Kai Tak Planning Review, T2 was revised to take the form of a
submarine tunnel.
2.7.24
The housing
development at Cha Kwo Ling and its associated local road network were put on
hold. To match these changes, CEDD engaged the TKO Study Consultants to carry
out additional services in 2006 to study alternative arrangements of TKO-LT
Tunnel at the Kowloon side.
2.7.25
According to the
recommendations of these additional services, the scheme for the Kowloon
Section was revised by adopting a different vertical alignment that descends at
a 6% gradient through the existing hillock at Cha Kwo Ling to below sea level
at the Cha Kwo Ling Public Cargo Working Area (PCWA) for connection to the T2
immersed tube tunnel. In addition, an interchange in Lam Tin (namely Lam Tin
Interchange) was proposed to connect T2 and the Kowloon section of TKO-LT
Tunnel to CKLR and the EHC. The revised layout is shown in Figure 2.10.
2.7.26
CEDD consulted
Kwun Tong District Council (KTDC) and the villagers’ organisations of Cha Kwo
Ling Village (CKLV) on the TKO-LT Tunnel project in May/June 2007. They raised
concerns on the clearance of part of CKLV and urged the road section at CKLV be
changed from depressed road to tunnel form to preserve the integrity of the
village community. In response to the request, CEDD engaged the TKO Study
Consultants to study alternative arrangements at TKO-LT Tunnel Cha Kwo Ling
Section to explore alternative conceptual road schemes to minimize the impact
on CKLV.
2.7.27
After
consideration of various alignment options, the consultants developed an
alternative scheme of a tunnel option at CKLV instead of depressed road, and
proposed a low level road alignment for TKO-LT Tunnel from ex-EHC casting yard
to Black Hill. Under this alternative scheme, some of the slip road connections
at Lam Tin Interchange could not be provided due to the limited available
space. Two additional branch tunnels are also required for the slip road
connections from TKO-LT Tunnel to EHC and T2 to Cha Kwo Ling Road.
2.7.28
The tunnel option
is shown in Figure 2.11. This
alternative tunnel option was supported by KTDC members during the consultation
meeting in May 2008. However, some private lot owners of CKLV raised serious concerns on the
potential impact of the tunnel option on the redevelopment rights of their
existing land lots as the tunnel would pass through the underground strata of their lots. They considered the tunnel option would prevent the
provision of deep foundation needed to support possible high rise buildings on
their lots upon redevelopment. A villagers’ organization also raised the “Fung
Shui” issue and requested for reviewing the road alignment.
Alternative Arrangements at Roads P2/D4
Junction
2.7.29
CEDD consulted
Sai Kung District Council (SKDC) on the TKO-LT Tunnel project in June 2007. The
District Council members raised a numbers of requests including the deletion of
the proposed Road D4 flyover and the provision of vehicular roads to Junk Bap
Chinese Permanent Cemetery (JBCPC). CEDD engaged
the TKO Study Consultants to study alternative arrangements at Roads P2/D4 Junction. The Consultants recommended to replace
the D4 flyover by a signal controlled junction with a grade separated cycle
track cum footpath crossing across the Roads P2/D4 junction, as shown in Figure 2.12. CEDD also agreed to allow flexibility in the layout
design of TKO-LT Tunnel such that vehicular connection points could be provided
should a vehicular road from JBCPC be proposed in the future. SKDC was
consulted again in January 2008 with the above scheme amendments. They welcomed
the proposed amendments and fully supported the implementation of the project.
Development of New Alignment Options
2.7.30
After the
consultation in Stage 1 public
engagement of the Project in 2009, alternative options have been developed and
considered for the six major road sections under TKO-LT Tunnel, namely Roads
P2/D4 Junction, Landscape Deck at Road P2, TKO Section, Lam Tin Hill Section,
Lam Tin Interchange and CKLV Section. The following sections present the
consideration of the alternatives for these road sections.
2.7.31
Under this
Project, the merits of and the need for providing the footbridge connecting
Park Central and Area 74S DO site (namely Northern Footbridge), and the walkway
linking it to the grade separated cycle-track cum footpath connecting G/IC site
at TKO Area 72, G/IC site at TKO Area 67 and Area 74S DO site (namely Southern
Footbridge) at Roads P2/D4 Junction were assessed.
2.7.32
Six options for
the cyclists’ crossing facilities across Roads P2/D4 Junction were studied:
·
Option
1 – By Zig-Zag Ramps at Cycle Track cum Footbridge
·
Option
2 – By Spiral Ramps at Cycle Track cum Footbridge
·
Option
3 – By Lifts and Cycle Track cum Footbridge
·
Option
4 – Separated Cycle Track
·
Option
5 – Subway
·
Option
6 – By Lifts and Cycle Track cum Footbridge + Separated Cycle Track
Option
1 – By Zig-Zag Ramps at Cycle Track cum Footbridge
2.7.33
The layout plan
and elevation of this Option are shown in Figure
2.13. Two proposed Zig-Zag Ramps at
3% gradient are provided at Southern Footbridge for cyclists to cross Road P2.
Option
2 – By Spiral Ramps at Cycle Track cum Footbridge
2.7.34
The layout plan
and elevation of this Option are shown in Figure
2.14. Two proposed Spiral Ramps with 25m radius are provided at Southern
Footbridge for cyclists crossing Road P2.
Option
3 – By Lifts and Cycle Track cum Footbridge
2.7.35
The layout plan
of this Option is shown in Figure 2.15. Additional lifts will be provided for
cyclists crossing Road P2.
Option
4 – By Separated Cycle Track
2.7.36
The layout plan
and elevation of this Option are shown in Figure
2.16. Under this option, the cycle
track will be separated from the Southern Footbridge. A separated cycle track will be provided for
the cyclists to cross Road P2 at the cycle track upon Road L673.
Option
5 – Subway
2.7.37
The layout plan
and elevation of this Option are shown in Figure
2.17. A subway in lieu of
footbridge, is considered as an alternative option for crossing
facilities. However, the subway is not
feasible due to the conflict with the existing box culvert across Road P2.
Option
6 – By Lifts and Cycle Track cum Footbridge + Separated Cycle Track
2.7.38
The layout plan
and elevation of this Option are shown in Figure
2.18. This option was developed
based on the comments received from the Value Management (VM) Workshop held in
October 2010 and is a coalescence of Option 3 & 4.
2.7.39
Study on the
arrangement on Roads P2/D4 Junction was presented in the Working Paper on Roads
P2/D4 Junction. Based on the findings in
this Working Paper and the comments received from various Government
departments, the following recommendations were proposed:
·
The
need for the Northern Footbridge is agreed;
·
a
linkage in the form of elevated walkway between the Northern Footbridge and Southern
Footbridge is not required as the bridges can be linked up via the podium of
the Area 74S DO Site;
·
For
cyclists’ crossing facilities. Option 6 is recommended as it has the advantages
of Option 3 and 4; and
·
To
facilitate traffic flow from northbound Road P2 to westbound Road D4, it is
recommended to adopt signalized junction at Roads D4/L721 Junction.
2.7.40
Under TKO Study,
a depressed road section of Road P2 with landscape deck at the eastern side of
Ocean Shores was proposed to be designed as DO site. A landscape deck of 200m
long is proposed to cover the depressed road as a noise mitigation measures. The general layout plan of the landscape deck
is shown on Figure 2.19.
2.7.41
During the meeting held in February 2013 amongst LCSD,
HyD and CEDD, LCSD agreed to undertake the maintenance responsibility of the
landscaping work on the landscape deck.
LCSD advised that the landscape deck to be further designed taking into
account of Tiu Keng Leng Park and shall be a passive landscape design. Details of the landscaping design shall be
subject to detailed design stage.
Tseung Kwan O Section (including TKO
Interchange)
2.7.42
Based on the
comments received in Stage 1 Public Engagement, three alternative options had
been developed at TKO Section and compared with the Conforming Option:
i.
Conforming
Option
ii.
Alternative
Option 1 – S-curve Tunnel with Toll Plaza Island Option
iii.
Alternative
Option 2 – Straight Tunnel with Toll Plaza Island Option
iv.
Alternative
Option 3 – Straight Tunnel without Toll Plaza Option
Conforming Option
2.7.43
The general
layout plan of the Conforming Option is shown in Figure 2.20. The tunnel follows an S-curve alignment. The tunnel
section is about 2.2km long at TKO Section. Reclamation is required for toll
plaza and connection roads (including Road P2) along the western coast of Junk
Bay. The extent of reclamation would be about 12ha.
Alternative
Option 1 – S-curve Tunnel with Toll Plaza Island Option
2.7.44
The general
layout plan of Alternative Option 1 is shown in Figure 2.21. The tunnel follows an S-curve alignment. The toll
plaza and associated bus-bus interchange are located on an artificial island
off the shoreline and therefore existing natural shorelines along the western
coast of Junk Bay would be preserved. The extent of reclamation would be 9.5ha.
The risk of hitting adverse ground conditions is considered relatively high.
Construction cost of this option is approximately less than the Conforming
Option by HK$0.3B.
Alternative
Option 2 – Straight Tunnel Option with Toll Plaza Island
2.7.45
The general
layout plan of Alternative Option 2 is shown in Figure 2.22. Commencing from the tunnel portal in Lam Tin, the
tunnel turns gradually from north-eastward to south-eastward and follows a
straight alignment. The length of main
road would be reduced by about 600m as compared to S-curve. An artificial
island and piled deck structure are proposed to accommodate the toll plaza and
associated bus-bus interchange. Existing natural shoreline along the western
coast of Junk Bay would therefore be preserved. The extent of reclamation would
be 9.5ha. The risk of hitting adverse ground conditions is considered
relatively lower than that of S-curve. However, the less streamlined
configuration of the toll plaza would have serious water quality and marine
ecological impacts at Junk Bay. Furthermore, less streamlined configuration of
the toll plaza would also create serious visual impact. Construction cost of
this option is approximately less than the Conforming Option by HK$1.2B.
Alternative
Option 3 – Straight Tunnel Option without Toll Plaza
2.7.46
The general
layout plan of Alternative Option 3 is shown in Figure 2.23. Similar to Alternative Option 2, this option follows a
straight alignment. Similar to Alternative Option 2, the length of main road
would be reduced by about 600m as compared to S-curve. It is proposed that no
toll plaza is to be provided under this option. Alternative tolling system is
required. The natural shoreline could be
preserved. Reclamation size is the
smallest amongst all the options (i.e. approximately 3ha). Construction cost of
this option is approximately less than the Conforming Option by HK$1.7B.
2.7.47
Evaluation of the
4 options at TKO Bay was presented in the Report on Evaluation of Alignment
Options at TKO Section. Amongst the
Options, the reclamation area under Alternative Option 3 is the smallest and
therefore the environmental impacts anticipated would be minimum. A straight
alignment will also offer better driving comfort than the S-curve. Size of the tunnel ventilation facilities is
envisaged to be smaller due to the shorter route than S-curve. The risk of hitting adverse ground conditions
is considered lower than that of S-curve.
Due to the shorter route and smallest reclamation area, the construction
cost of the tunnel is the lowest amongst the options. The natural shoreline
along the western coast of Junk Bay would also be preserved.
2.7.48
After a
comprehensive comparative evaluation of the Conforming Option and the 3
alternative options, Alternative Option 3 was selected as the preferred scheme
for the TKO Section in light of the need of least reclamation, provision of
shorter route, and the most cost effectiveness and acceptable on environmental
grounds. The evaluation results are summarized
in Table 2.7.
Table 2.7 Summary of Options Evaluation at Tseung Kwan O Section
|
Features |
Conforming Option |
Alternative Option 1 |
Alternative Option 2 |
Alternative Option 3 |
|
Alignment: |
S-curve |
S-curve |
Straight |
Straight |
|
Length
of main road: |
4.8km |
4.8km |
Shorter than the Conforming Option by
600m, but longer slip roads connecting Road P2 |
Shorter than the Conforming Option by
600m |
|
Toll
plaza and associated bus-bus interchange be provided? |
Yes |
Yes |
Yes |
No, tolling facilities to be further
considered. |
|
Reclamation
Planning and Land Use: |
·
About
12ha of reclamation in Junk Bay is required to accommodate the toll plaza,
associated facilities and the connection roads. ·
Length
of cycle track starting from the Ocean Shores to the end of CBL (via TKO-LT
Tunnel and CBL interchange): 2040m |
·
About
9.5ha of reclamation in Junk Bay is required to accommodate the toll plaza,
associated facilities and the connection roads. ·
Approximately
13,160m2 of open space would be reduced as compared with the
Conforming Scheme. ·
Length
of cycle track starting from the Ocean Shores to the end of CBL (via TKO-LT
Tunnel and CBL interchange): 2020m |
·
About
9.5ha of reclamation in Junk Bay is required to accommodate the toll plaza,
associated facilities and the connection roads. ·
Approximately
12,421m2 of open space would be reduced as compared with the
Conforming Scheme. ·
Length
of cycle track starting from the Ocean Shores to the end of CBL (via TKO-LT
Tunnel and CBL interchange): 1992m |
·
About
3ha of reclamation in Junk Bay is required for construction of Road P2 and
associated connection roads. ·
Approximately
11,807m2 of open space would be reduced as compared with the
Conforming Scheme. ·
Length
of cycle track starting from the Ocean Shores to the end of CBL (via TKO-LT
Tunnel and CBL interchange): 2029m |
|
Natural
shoreline be preserved? |
No |
Yes |
Yes |
Yes |
|
Geotechnical
risk in tunnel construction: |
High |
High |
Low |
Low |
|
Visual Impact: |
Medium |
High |
Very
High |
Low |
|
Environmental Impacts: |
High
marine ecology impact due to reclamation |
Medium
marine ecology impact due to slightly-reduced reclamation |
Serious
environmental impacts (particularly water quality & marine ecology) due
to the protruding of reclamation into Junk Bay |
Lowest
environmental impacts due to minimum reclamation required |
|
Construction Cost: |
~
HK$80B (baseline) |
-HK$0.3B |
-HK$1.2B |
-HK$1.7B |
2.7.49
During the
meetings with the residents of Hong Nga Court and the Incorporated Owners of
Hong Nga Court in July 2010, it is noted that they strongly object to the
alignment passing under the building structures of Hong Nga Court. In addition, a local DC member suggested an
alternative alignment at this section.
2.7.50
To address the
above concerns, the Original Alignment at Lam Tin Hill Section (Figure 2.24) was reviewed and an
alternative alignment was proposed, namely Alternative Alignment No. 1 (Figure 2.25) in order to minimize the
impact to Kwong Ching House. During a meeting with a local DC member, another alternative
alignment, namely Alternative Alignment No. 2 (Figure 2.26) was also suggested for consideration.
2.7.51
An evaluation of
the Original Alignment and the Alternative Alignment No. 1 and No. 2 has been
undertaken and the results are presented in the Working Paper on Proposed
Alignment at Hong Nga Section. The
evaluation results are summarized in Table
2.8.
Table 2.8 Summary of
Options Evaluation at Lam Tin Hill Section
|
Features |
Original
Alignment |
Alternative
Alignment No. 1 |
Alternative
Alignment 2 |
|
Traffic
operation: |
Desirable |
Undesirable |
Undesirable |
|
Land
impact to private lots: |
Small |
Medium |
Large |
|
Land
impact to Kwong Ching House |
Medium |
Small |
No |
|
Construction
Cost: |
Medium |
High |
Low |
2.7.52
Based on the
findings, Alternative Alignment No. 1 is not recommended as the sightline of
the tunnels could not comply with the desirable minimum value as stipulated in
the TPDM. In comparison, Alternative Alignment No. 2 suggested by the DC member
is not recommended as one of the main tunnel and the branch tunnel would pass
under Chung Pak House. Under the
Original Alignment, the main tunnels and the branch tunnels will be about 90m
and 67m below Kwong Ching House respectively within sound rock with Grade III
or better. As a result, tunnel
construction would unlikely to affect Kwong Ching House. The Original Alignment was therefore
recommended.
2.7.53
As discussed in Section 2.2.1, TKO-LT Tunnel, Trunk
Road T2 and CKR will form the proposed Route 6.
Lam Tin Interchange will connect with the other strategic trunk roads in
the area. The layout and design of the
interchange is critical to its functional objective.
2.7.54
Five options with
different connectivity were developed for the Lam Tin Interchange and they are
shown in Figures 2.27 to 2.31, respectively.
2.7.55
As stated that
TKO-LT Tunnel, Trunk Road T2 and CKR will form the proposed Route 6. Lam Tin Interchange will connect with the
other strategic trunk roads in the Kwun Tong area. The general arrangement of slip road in the
interchange is critical to its functional objective. Five options with
different connectivity were developed for the Lam Tin Interchange and described
as follows:
2.7.56
Option 1 has the
simplest layout. However, it cannot
provide a direct connection between Trunk Road T2 and EHC and therefore cannot
distribute traffic effectively between Routes 2 and 6 in East Kowloon. The
layout is indicated in Figure 2.27.
2.7.57
Option 2 provides
direct connection between TKO-LT Tunnel/T2 and EHC, it impacts significantly on
the existing EHC tunnel area and would require new separated satellite toll
booths at either side of the existing booths.
Traffic exiting EHC to TKO-LT Tunnel/ T2 would have to diverge sharply
from traffic exiting EHC to Kwun Tong Bypass before it passes through the toll
booths as shown in Figure 2.28.
Thus, Option 2 is not recommended in view of traffic safety.
2.7.58
Option 3 does not
induce any adverse effect on existing EHC tunnel operation, by routing the link
road connections between TKO-LT Tunnel/T2 and EHC, whilst maintaining all
desired movements. The layout is indicated in Figure 2.29. However, the overall layout of Option 3 is considered
relatively complicated and the mostly costly scheme, and there is concern that
it could also confuse motorists.
2.7.59
A gyratory system
is adopted in Option 4 to reduce the overall length of the slip roads. However, there are too many decisions to be
made at the gyratory system and would confuse motorists. The layout is indicated in Figure 2.30.
2.7.60
Option 5 is a
hybrid of Options 1 and 3, it includes all desired road connections while
maintaining a relatively simple layout. It also has the least impacts on EHC.
The layout and the slip roads arrangement are shown in Figure 2.31. Based on the above evaluation of all options, Option 5
is recommended as the most reasonable scheme.
2.7.61
Based on the
above evaluation of the options, Option 5 is recommended to carry forward and
form the base for further study. Two
options, namely Depressed Road Option and Tunnel Option were developed based on
Option 5. Two physical models were
created based on Depressed Road Option and Tunnel Option for the 2nd Stage
Public Engagement at CKLV Section and Yau Lai Estate.
2.7.62
Evaluation of the
Depressed Road Option and Tunnel Option is summarized in Table 2.9. The layout plans and photos showing the schematic layout
of the Depressed Road Option and Tunnel Option are attached in Figure 2.32.
Table 2.9 Summary of
Options Evaluation at Lam Tin Interchange Section
|
Features |
Tunnel
Option |
Depressed
Road Option |
|
Volume
of excavation materials: |
More |
Less |
|
Length
of slip roads: |
Longer |
Shorter |
|
Environmental
Impacts: |
Lower |
Higher |
|
Gradient
of the main roads: |
More gentle |
Steeper |
|
Construction
cost: |
Higher |
Lower |
|
Other
cons: |
No access from CKR to Lam Tin and EHC
during night time closure of T2 eastbound tube. Drivers need to use alternative route |
Traffic diversion is required on Lei Yue
Mun Road during construction |
2.7.63
In order to
determine the “Recommended Scheme” at CKL for the Project, 4 options were
developed. They are:
i.
H1a –
Depressed Option with tunnel alignment pass through the middle of CKLV as shown
in Figure 2.33
ii.
H1b –
Tunnel Option with tunnel alignment pass through the middle of CKLV as shown in
Figure 2.34
iii.
H2a –
Depressed Option with tunnel alignment pass through the previous Four Hills
Public School as shown in Figure 2.35
iv.
H2b –
Tunnel Option with tunnel alignment pass through the previous Four Hills Public
School as shown in Figure 2.36
2.7.64
Evaluation of the
4 options was presented in the Report on Evaluation of Alignment Options at
CKL. H1a is the least costly
option. However, it would have major
impact on CKLV, resumption and clearance of private lots and government up to
about 500 residents. The depressed road
would create relatively higher potential environmental impact to CKLV and Yau
Lai Estate due to corresponding Lam Tin Interchange arrangement. H2a is a depressed road scheme and cost
approximately HK$1.0B more than H1a.
However, it would require permanent change to the seabed profile. Moreover, the alignment will be very close to
Tin Hau Temple and have high potential environmental impact to CKLV and Yau Lai
Estate due to corresponding Lam Tin Interchange arrangement. The previous Four Hills Public School is
required to be demolished to facilitate the tunnel construction. H2b is a
tunnel scheme and cost HK$2.1B more than Option H1a. No resumption of private lots is
required. However, the tunnel will
affect the previous Four Hills Public School.
H1b cost approximately HK$1.6B more than H1a. However, clearance to CKLV could be
avoided. Environmental impact to CKLV
and Yau Lai Estate would be lower than depressed road schemes. However, the underground strata of few
private lots above the Option H1b’s tunnels will be affected.
2.7.65
The evaluation is
summarized in Table 2.10 as below.
Table 2.10 Summary of Options Evaluation at Cha Kwo Ling Village
Section
|
|
Option H1a |
Option H1b |
Option H2a |
Option H2b |
|
Alignment &
Characteristics: |
Pass through middle of CKLV in the form of depressed
road |
Similar alignment as Option H1a, but pass through
the middle of CKLV in tunnel form |
Pass through CKLV at the former Four Hills Public
School in the form of depressed road |
Similar alignment as Option H2a, but pass through
CKLV at the former Four Hills Public School in tunnel form |
|
Construction method: |
Cut-and-Cover |
Drill-and-Blast+mechanical breaking |
Cut-and-Cover |
Cut-and-Cover |
|
Require resumption of
private land or clearance of squatters: |
Yes |
No |
No |
No |
|
Impact on land in the
vicinity: |
CKLV is separated into two parts by depressed road |
Creation of easement in underground stratum within
tunnel protection area |
Less impact on village integrity. The open space near Tin Hau Temple would be
temporarily used during construction period |
Less impact on village integrity. The open space near Tin Hau Temple would be
temporarily used during construction period |
|
How much longer is the main
road section compared with option H1a: |
- |
- |
220m |
230m |
|
Visual impact on nearby
area: |
Visual impact
on CKLV and Yau Lai Estate is quite significant |
Visual impact on CKLV and Yau Lai Estate is less
significant than Option H1a |
Visual impact on CKLV and Yau Lai Estate is similar
to Option H1a |
Visual impact on CKLV and Yau Lai Estate is less
significant than Option H1a |
|
Is there available access
from CKR to Lam Tin and Eastern Harbour Crossing during night time closure of
Trunk Road T2 east-bound tube: |
Yes |
No |
Yes |
No |
|
Total Construction Cost
(incl. TKO-LT Tunnel & Trunk Road T2) |
HK$14.0B |
HK$13.4B |
HK$15.0B |
HK$16.1B |
2.7.66
As there are
merits and drawbacks for each options.
All the 4 options were presented to the public for comments,
particularly the residents of CKLV during the 2nd Stage of Public Engagement.
Minimisation
of Reclamation
2.7.67
Followed a series
of public engagement activities conducted in late 2010, majority of the public
views supported the Straight Tunnel Option without Toll Plaza. Under this alignment option, the extent of
reclamation is largely reduced and the required reclamation is optimized to
about
Recommended
Scheme
2.7.68
Further to views
obtained from the 1st Stage and 2nd Stage of the Public Engagement, the
Recommended Scheme of the Project is developed.
2.7.69
At Roads P2/D4
Junction, Option 6 (i.e. By Lifts and Cycle Track cum Footbridge + Separated
Cycle Track) is the preferred option. As
agreed amongst the relevant Government departments, the linkage between the Northern
Footbridge and Southern Footbridge is not required.
2.7.70
Further to the
2nd stage of public engagement and the meeting amongst Government departments
in February 2013, the landscape deck with length 200m at Road P2 is formed.
2.7.71
In view of
geotechnical risks in tunnel construction, environmental impacts (including
water quality, marine ecology and visual impacts), cost implication and public
preference, Alternative Option 3 (i.e. Straight Tunnel Option without Toll
Plaza) is the most preferred option at TKO Section.
2.7.72
Further to the
2nd stage of public engagement, it is noted that the local residents have no
objection to the Original Alignment at Lam Tin Hill Section.
2.7.73
In consideration
of the opinions received during the 2nd Stage Public Engagement and in order to
reduce the impacts to CKLV and Yau Lai Estate, H1b is the best option at CKLV
Section.
2.7.74
The Recommended
Scheme for the project is the hybrid of Alternative Option 3 at TKO Section,
Original Alignment at Lam Tin Hill Section, Lam Tin Interchange Tunnel Option
and H1b at CKLV Section. The general layout plan of the Recommended Scheme is
shown in Figure 2.37.
2.7.75
The major views
on the Recommended Scheme during the Stage 3 public engagement are listed as
below:
· To ensure minimal nuisance to the
public during and after construction (including tunnelling work under existing
building structures).
· To implement appropriate
mitigation measure to alleviate the environmental impacts included by the
project including noise, air quality, light and visual impacts.
· To consider if further mitigation
measures can be provided at Lam Tin Interchange to further reduce the
environmental impacts, particularly noise and air pollution and light effect to
Yau Lai Estate.
· To preserve CKL Village and
avoid/minimize nuisance/impact during construction.
· To address the traffic problem on
local roads during and after construction of the project.
· To try avoiding the tunnel to pass
underneath the existing buildings
· Provide more greening measures
upon the landscape deck near Ocean Shore.
Alternative Alignments for Kwun Tong
Section
2.7.76
During the 2nd
stage PE, comments have been received on considering alternative location of
Kwun Tong side (KT) interchange. In view of the received comments, it was
considered necessary to conduct a supplementary study on alternative alignments
for Kwun Tong Section to address the received comments with the purpose to
justify that the Recommended Scheme endorsed in the Project Steering Group in
December 2010 is the best option.
2.7.77
Kwun Tong
district has been fully occupied by high-rise residential buildings and
industrial buildings. In view of the site constraints and the topographic
conditions in Kwun Tong district, the desirable location of an alternative
interchange shall be an undeveloped government land and near to the major
traffic network in Kwun Tong district. As a result, only two suitable locations
for the interchange at Kwun Tong side were identified for further study. They
are (i) Cha Kwo Ling Public Cargo Working Area (CKLPCWA) and (ii) the Laguna
Park with Wai Yip Street Nullah respectively.
2.7.78
Based on the
available locations of alternative Kwun Tong side interchange, three
Alternative Alignments were developed as shown in Figure 2.38. Each of them would have an interchange. For
Alternative Alignment 1, the interchange would be located at Laguna Park while
for Alternative Alignment 2 and Alternative Alignment 3, the interchanges would
be located at the CKLPCWA. All the alignments would connect the Trunk Road T2
at Kwun Tong and connect Road P2 and CBL at Tseung Kwan O respectively.
Alternative Alignment 1
2.7.79
As shown in Figure 2.38, the western end of the
Alternative Alignment 1 will connect Trunk Road T2 at Kwun Tong. The tunnel
will enter underneath the existing Wai Yip Street Nullah and head towards Lei
Yue Mun Road and then a horizontal curve would follow towards the Junk Bay. The
tunnel would then be in straight form and connect Road P2 and Cross Bay Link at
Tseung Kwan at the eastern end. As shown in Figure 2.39, Figure 2.40
and Figure 2.41, the administration
building of this alignment will be built at Kai Tak while the mid-ventilation
building will be built at the CKLPCWA and to be connected the TKO-LT Tunnel by
mid-ventilation adit. Two ventilation buildings will be built at the tunnel’s
eastern and western portals respectively.
2.7.80
Due to the
existing foundation of Kwun Tong Bypass and the foundation of Wai Yip Street,
the road level of the tunnel right beneath of Wai Yip Street was designed to be
at least as deep as -31 mPD in order not to interfere the zone of bulb of
pressure of foundation of Wai Yip Street Bridge.
2.7.81
In view of the
extremely difficulty in emergency operations and the cost non-effectiveness of
slip roads arrangement, this option is considered not viable and not considered
for further evaluation.
Alternative Alignment 2
2.7.82
As shown in Figure 2.38, the western end of the
Alternative Alignment 2 will connect Trunk Road T2 at Kwun Tong. The eastern
end of the tunnel will connect Road P2 and Cross Bay Link at Tseung Kwan O. The
tunnel will enter the CKLPCWA. As shown in Figure
2.42, the administration building of this alignment will be built at Kai
Tak interchange of T2 while the mid-ventilation building will be built at the
FEHD Transport Section Cha Kwo Ling Vehicle Depot. Two ventilation buildings
will be built at the tunnel’s eastern and western ends respectively.
2.7.83
An interchange
would be formed at CKLPCWA. Two slip roads will be constructed at the CKLPCWA
as shown in Figure 2.43. Slip Road
S1 will provide traffic route from Trunk Road T2 to Wai Yip Street while Slip
Road S3 will provide traffic route from Wai Yip Street to TKO – LT Tunnel EB.
Another slip road EHC 1 will be constructed at FEHD Vehicle Depot to provide an
indirect linkage from EHC to TKO-LT Tunnel via Cha Kwo Ling Vehicle Depot
carriageway to Cha Kwo Ling Road, Wai Yip Street and finally Slip Road S3.
2.7.84
In order to
comply with the PHO by avoiding permanent reclamation in the harbour, the Slip
Road S1 is designed to be under the seabed level at about -32mPD before
entering the existing seawall at CKLPCWA.
Under Alternative Alignment 2, EHC2 for traffic from TKO-LT Tunnel
eastbound to EHC as provided in the Recommended Scheme could be maintained.
Alternative Alignment 3
2.7.85
As shown in Figure 2.38, Alternative Alignment 3
adopts similar alignment of the Western Coast Road under the TKO further
study. As shown in Figure 2.44, Figure 2.45
and Figure 2.46, the administration
building of this alignment will be built at TKO Interchange while the
mid-ventilation building will be built at the CKLPCWA and to be connected the
TKO-LT Tunnel by mid-ventilation adit. Two ventilation buildings will be built
at the tunnel’s eastern and western ends respectively.
2.7.86
The western end
of the Alternative Alignment 3 will connect Trunk Road T2 at Kwun Tong. The
tunnel was designed to continue the alignment of Trunk Road T2 and to go
straight under the seabed until it reaches Junk Bay. A horizontal curve was
introduced and the tunnel will pass through Lei Yue Mun and reach Junk Bay. The
eastern end of the tunnel will finally connect Road P2 and Cross Bay Link at
Tseung Kwan O.
2.7.87
The interchanges
are proposed at CKLPCWA and at Lei Yue Mun as shown in Figure 2.44, Figure 2.45
and Figure 2.46. Slips Road S4 is
designed to connect Kwun Tong district from westbound of TKO-LT Tunnel while
road users could exit eastbound of T2 to Kwun Tong district by taking Slip Road
S1. Details of interchange are shown in Figure
2.47, Figure 2.48 and Figure 2.49.
2.7.88
In Alternative
Alignment 3, the long slip road in single tube tunnel form is not viable as it
is difficult for emergency operation.
Alternative interchange at Lei Yue Mun also shows that the slip road
arrangement is not viable due to the permanent reclamation inside Victoria
Harbour required for the tunnel construction.
Alternative Alignment 3 is therefore not viable and not further
considered.
Comparison between Recommended Scheme and
Alternative Alignment 2
2.7.89
Alternative
Alignment 2 is comparatively a non-infeasible alignment amongst the three
Alternative Alignments. It would provide three direct Slip Roads and one
indirect Slip Road to form an interchange at CKLPCW.
2.7.90
When comparing
the Recommended Scheme and Alternative Alignment 2, the traffic performance of
Alternative Alignment 2 is unacceptable. In addition, the slip road
connectivity and traffic operations of the Alternative Alignment 2 are under
performance and much worse than Recommended Scheme.
2.7.91
Under Alternative
Alignment 2, environmental impact would be concentrated in the vicinity of
Laguna City and therefore affecting more sensitive receivers in Kwun Tong
district than the Recommended Scheme.
2.7.92
As a result, the
Recommended Scheme is recommended after the evaluation.
2.8 Environmental Friendly Design
2.8.1
In order to
preserve the environment in the vicinity of the project, environmental friendly
designs are adopted in different locations as far as practical. The environmental friendly designs are
summarized in the followings:
Road P2
2.8.2
In order to
minimize the visual and noise impact to the nearby residential area, Road P2
will be in the form of depressed road such that the road level will be below
ground and sea level.
2.8.3
A 200m long
landscape deck will also be provided to cover the depressed road at the road
section immediately next to Ocean Shores.
The landscape deck connects the amenity areas on both sides of Road P2
and provide a convenient access to the footpath and cycle track along the
waterfront.
Tseung Kwan O
Section
2.8.4
A “Straight
tunnel alignment without toll plaza option” is adopted for TKO Section. A straight tunnel alignment not only attains
a good engineering design but also minimize the C&D material when compared
with the S-curve tunnel from TKO study.
2.8.5
By omitting the
toll plaza, the reclamation extent and the associated environmental impact such
as water quality, marine ecology will be minimized.
Lam Tin
Interchange
2.8.6
Two options:
Tunnel Option and Depressed Road Option were formed under this Project and the
Tunnel Option has been adopted. In the
Tunnel Option, the main carriageway and most of the slip roads are located
below the existing ground level such that the carriageways could be ‘hidden”
from the nearby residential area as far as possible.
2.8.7
An integrated
design with noise shelter comprising a landscape deck and light green-coloured
noise enclosures will be provided along the main carriageway as noise and
visual impact alleviation measures and flooding preventive measures taking into
account of the deep carriageway alignment.
2.8.8
Together with the
green terrace roofs upon the tunnel facilities. shrubs and trees will be
planted at the landscape deck and the adjacent area to provide a green
environment at the interchange.
2.8.9
To further
minimize the environmental impact and light nuisance, some part of the slip
roads are in tunnel form to alleviate vehicles’ visual and noise impact.
Cha Kwo Ling
Section
2.8.10
The Tunnel Option
as mentioned in paragraph 2.8.6 will avoid clearance of any building structures
in Cha Kwo Ling Village (CKLV). The
current alignment will avoid running beneath Tin Hau Temple or former Four
Hills Public School in the village.
2.8.11
Mechanical
breaking method or other non-blasting methods will be deployed for constructing
the tunnel at this section such that the potential impacts on the village’s
residents and building structures in the construction phase will be minimized.
2.9
Construction
Methodologies
2.9.1
This section describes the planning of the construction
of the project, covering the key aspects including the envisaged methods of
tunnel construction, reclamation and other infrastructure, and the sequence of
works.
Construction Methods for Tunnels
2.9.2
Based on the available geological profile, it is
envisaged that tunnel excavation will be mostly carried out in good quality
granite and volcanic rock masses. They are typically excavated by either drill
& blast or by tunnel boring machine (TBM). Other forms of excavation such
as mechanical and chemical splitting are not cost effective except for either
small volume of excavation or at locations where blasting would pose too great
nuisance or be hazard. Whilst it is practicable to excavate tunnel by either
method, the preferred method can only be determined after study of the
constraints on the construction.
Drill & Blast Method
2.9.3
Drill and blast tunnelling is a cyclic operation
comprising, the drilling of charge holes for the explosives, blasting of the
face, and removal of the spoil either concurrent with, or prior to, the
installation of temporary support to the tunnel if required. In addition to the
basic components of the tunnelling cycle in poor ground probe and ground
treatment hole drilling and grouting are required. Drill and blast excavation
is very efficient for tunnels where multiple faces can be excavated
simultaneously and there are few restrictions on the delivery, storage and use
of explosives.
2.9.4
Typically the excavation phase is completed before the
permanent lining is provided to the tunnel. Prior to the provision of the
permanent lining temporary support is provided where necessary to secure the
opening. The temporary support comprises various elements including, rock
bolts/dowels, shotcrete, and steel arches used either singly or in combination
depending on the nature of the rock mass.
2.9.5
The permanent lining to the tunnel normally comprises
cast mass concrete but could comprise high quality shotcrete, or on occasion
precast concrete segments.
2.9.6
When excavating through water bearing ground control
of water inflow can only be controlled by methodical injection grouting through
overlapping fans of drill holes in advance of the tunnel face. Pre-grouting
prior ahead of the face has been proven to be the only effective method of
controlling groundwater inflow during excavation. Therefore continuous probing
as the face advances is essential to ensure that any water bearing zones or
discrete features are located and pre-treated. It must be noted that it is only
necessary to control groundwater inflows in situations where
·
Groundwater drawdown could induce
movement at settlement sensitive structures;
·
Inflow could initiate tunnel
instability;
·
Inflow exceeds pumping capacity and
could inundate the tunnel; and
·
Water sources (wells/aquifers) could
be affected.
2.9.7
In all other situations the standard practice is to
seal off groundwater inflow as part of the permanent lining construction
activity.
2.9.8
Excavation of tunnels by blasting often gains an
advantage by providing short mobilisation times, and allowing the use of
multiple excavation headings, as opposed to excavation of tunnels by TBM. The use
of a TBM will typically become more viable as the length of the tunnel
increases.
2.9.9
As described above, excavation by blasting is a cyclic
sequence, consisting of drilling – blasting – venting – mucking – installing
support. The overall duration of the cycle will be largely dependent on the
time taken to drill the face, and the time taken to muck out the blasted rock.
It is therefore possible to adjust the advance per blast in order to achieve an
optimum production rate. Where only one blast a day is possible, it may be best
to make greatest advance possible in one blast. Where multiple blasting is
possible, it may be best to shorten the round in order to ensure two or even
three blasts can be made within the allowable working period.
2.9.10
When blasting in an urban environment, other external
factors may affect the blasting method. Of primary concern is the supply of
explosive. It is often not possible to store explosives on site in urban areas,
and daily delivery from Mines Division is required. This delivery is typically made between 11am
and 2pm each day, and the explosives are expected to be used immediately
resulting in a single blast each day during the afternoon.
2.9.11
Another influence in urban areas is the presence of
nearby sensitive receivers, such as housing, schools or hospitals. These may
require that blasting is carried out at certain times of the day. In
combination with the daily deliveries, it is very common that blasting is
carried out in urban areas during the afternoon rush hour, when other environmental
factors help reduce the apparent effects during blasting.
Tunnel Boring Machine (TBM) Method
2.9.12
Section of TBM for tunnel excavation is primarily
governed by the geological conditions for the excavation materials to be
encountered. The variation of the geological conditions over the entire length
of the tunnel will govern design of the TBM and ancillary equipment to be
provided. Key issues that need to be considered are listed as follows:
·
Permanent support or finishing
requirements of the tunnel (e.g. segmental concrete lining, cast in-situ
concrete lining or even bare rock) will govern whether the lining is installed
either as part of the excavation phase on the TBM, as a consequential activity
behind the TBM or after completion of TBM excavation.
·
Design issues for temporary works
with respect to bolting or anchor diameters and lengths or shotcrete thickness
for rock tunnel will also play a major role in ancillary equipment selection
and location on the TBM or backup train.
·
The anticipated groundwater to be
encountered during excavation is a key consideration in selection of TBM type.
The allowable amount of groundwater inflow to the excavated tunnel during
construction and to the completed tunnel after commissioning would dictate the
extent of ground water control of both the TBM design and tunnel lining design.
·
The tunnel alignment, including both
horizontal and vertical alignment will govern the TBM cutterhead, re-gripping
dynamics and muck haulage system. Minimum horizontal and vertical curves are
also critical for the design of TBM and may also affect the stroke length and
gripper orientation for rock tunnel.
Comparison of Drill & Blast against TBM
Method
2.9.13
The table below summarizes the comparison of drill & blast method
against TBM method for construction of TKO-LT Tunnel.
|
|
Drill & Blast Method |
TBM Method |
|
Cross
Section |
·
Horse shoe shaped tunnel
cross section, more efficiency of space. ·
Less limitation for the
ratio of tunnel width and height. ·
Flexible to change the
tunnel section, such as road widening to achieve required sightline at tight
curve. |
·
Circular tunnel cross
section, less efficiency of space. ·
The ratio of tunnel width
and height are fixed (limited by diameter of boring). ·
Adoption of typical size
precast segmental lining. Road widening by costly local drill & blast
after TBM excavation. |
|
Alignment |
·
Allow turning radius < 1360m by road
widening. |
·
Post-TBM road widening
excavation would be difficult to section with turning radius < 1360m.
Typical segmental lining could not be adopted for widened road section. ·
Bigger TBM is required
for the entire tunnel section to avoid road widening. |
|
Construction |
·
Flexible to change in
construction method to tackle the weak zone/fault excavation. ·
Commence immediately
after award of blasting permit. ·
Vibration caused by
blasting on nearby sensitive receivers is major concern. ·
Monthly excavation rate
can be up to 150m month per blast face. ·
Normally use cast in-situ
concrete lining. |
·
Frequent probing and
ground treatment at localised weak zone, such as fault influence zones of
poor quality rocks, is required, which is time consuming for the Gripper or
Shield TBM. ·
Normally takes 14 months
for TB procurement. ·
Ground borne noise caused by TBM excavation on
nearby sensitive receivers is the major concern. ·
Monthly excavation
progress rate can be up to 400m; however the procurement time will normally
outweigh the progress rate for short to medium length tunnel. |
|
Land
Requirement |
·
Neutral in comparing with
TBM excavation method as it is normally not possible to establish explosive
magazine at Kowloon side. |
·
Neutral in comparing with drill & blast
excavation method. |
|
Excavation
Material |
·
Generate smaller amount
of excavated rock than TBM tunnel. ·
The excavated materials
could be recycled for backfilling after cleaning and sorting. |
·
Generate greater amount
of excavated rock than drill & blast tunnel. ·
The excavated materials
could be recycled for backfilling after cleaning and sorting. |
|
Cross
Passage |
·
Cross passage could be
easily formed by drill & blast. ·
Can be excavated soon
after tunnel passes, allowing transfer of construction plant between. |
·
Post-TBM excavation is required and would be
difficult to form the cross passage. ·
Special segmental lining for dismantling or no
segment installed at cross passage location. |
|
Cost |
·
The capital cost for TBM and associated plant and
equipment is much higher than that required for drill & blast method.
Thus, for tunnel in good quality of rock, drill & blast excavation method
is considered cheaper than TBM excavation method. |
·
Consider higher than drill & blast excavation
method for tunnelling in good quality of rock. |
Construction of Main Tunnel and Branch
Tunnel
2.9.14
Due to the hardness of the rock and the size of tunnel, the bored tunnel
will be constructed by the Drill and Blast (D&B) method in order to achieve
the construction programme within reasonable time and cost. This is commonly
used in Hong Kong for the excavation of road tunnels. As for the TBM tunneling
method, the following factor considered unfavorable to the road tunnel
including:-
·
The TBM tunnel will be circular and there will be wastage of excavation
and filling for the tunnel invert;
·
The TBM tunnel will be formed in single size which is unable to allow for
intermediate ventilation jet fan and widening in curved section unless
enlarging the entire tunnel size.
2.9.15
Therefore, the drill and blast method is considered to be a more cost
effective construction scheme for the tunnel excavation.
2.9.16
A blasting assessment has been carried out to determine the charge weight
for blasting as to control the peak particle velocity (PPV) of adjacent
features within limit, detail should be refer to Preliminary Blasting
Assessment Report.
2.9.17
Geological and hydrogeological assessment has been carried out to
investigate the effect on adjacent sensitivity receivers by the tunnel
excavation works. The assessment determines the water inflow criteria into
tunnel
2.9.18
The envisaged tunnel excavation and support works of the rock tunnel are
listed in the sequences below:
·
Probe to investigate the water inflow ahead of the tunnel;
·
Ground treatment in the form of pre-grouting to control ground water
ingress if necessary;
·
Excavate the tunnel by drill and blast method;
·
Carry out geological mapping and select primary support design in
accordance with the pre-determined support requirements based upon the NGI-Q
system;
·
Install primary rock support using spot dowels, systematic dowels and
shotcrete;
·
For ground conditions with support category worse than class 6, a site
specific design will be carried depending the actual geological and
hydro-geological conditions;
·
Carry out post excavation grouting if ground water inflow remains above
specified limits.
2.9.19
Groundwater inflows around the tunnel construction works will be
controlled to limit the ground water drawdown according to the Geotechnical
Assessment Report. Pre- and post-grouting will be carried out in accordance
with the water inflow criteria.
2.9.20
In the vicinity of the existing sensitive feature or adverse geological
condition (e.g. insufficient rock cover), portion of the tunnels will also be
constructed by non-blasting (e.g. hydraulic or chemical splitting) or
mechanical method (e.g. drill and break) to reduce the impact of blasting to
the surrounding features.
2.9.21
For the mixed ground condition, NATM phased tunnel excavation method may
be adopted in order to control the ground movement and tunnel stability. And an
undrained tunnel permanent lining will be applied to minimize the ground water
drawdown.
Construction of Cha Kwo Ling (CKL) Tunnel
Section
2.9.22
CKL tunnel section from the western end of Lam Tin Interchange towards
west reaching Cha Kwo Ling Village
(CKLV) is about 400m.
2.9.23
The soil geology of the Cha Kwo Ling area is predominately Mount Butler
Granite (Klb) underlying the reclamation fill along the coastline. Klb Granite
mainly comprises equigranular fine and fine-to-medium grained biotite granite.
Base on the available GI information, the rock quality is good, with RQD 100
for most of the recovered rock core. The superficial materials mainly comprise
a Fill layer of 2 to 3m thick overlaying saprolite of 1 to 9m thick.
2.9.24
As shown in Figure 2.50, CKL tunnel section (from the western end
of Lam Tin Interchange towards west before reaching CKLV) which is about 130m
will be excavated by drill and blast method. The remaining of Cha Kwo Ling
tunnel section with 270m will be excavated by mechanical breaking or other
non-blasting methods to minimize impact to CKLV. Excavated materials mucked out
from the tunnel will be delivered to the tunnel portal and disposal off site
via conveyor belt to CKL public cargo area and then to Lam Tei Quarry by sea
transport. The expected pull length for one blast per day is about 4m. Taking
the excavation area at each tube of about 145m2, there will about
580m3 excavated materials (approx. 80 loaded truck trips) to be
disposed off each day per tube via sea transport to the following:
·
Grade II or above rock to Lam Tei Quarry or
Tuen Mun Area 38 Fill Banks
·
Grade III or below rock and inert C&D
materials to Tseung Kwan O Area 137 Fill Bank
2.9.25
Preliminary blasting assessment have been prepared for ensuring the
impacts due to designed charge-weight, in terms of vibration (ppv) and
air-over-pressure (AOP), on the CKLV and other stakeholders within the
influence zone area are within the acceptable limits. Monitoring plan will be
prepared as well for ensure adequate control and monitoring for the concerned
stakeholders during blasting.
2.9.26
At the Cha Kwo Ling Public Cargo Working Area, the superficial materials
generally comprise a Fill layer of 10 to 20m thick overlaying saprolite of 2 to
5m thick. Locally, occurrences of marine deposits (1to 3m thick) and alluvium
(3 to 8m thick) are evident in the available borehole records. In view of the
conditions of the existing squatters at CKLV at which the reminder of CKL
Section (about 250m) passing underneath up to the interface with landfall
section of Trunk Road T2 at the existing Public Cargo Working Area,
non-blasting excavation method, e.g. drill & splitting, chemical splitting
is recommended though this section of tunnel has been lowered to have
sufficient rock cover enabling excavation by drill & blast method.
Arrangement for disposal of excavated materials is similar to the above.
2.9.27
In terms of land impact, as there will be no physical impacts on existing
private lots, unauthorized dwellings Government STT, GLA and TGLA lots within
CKLV during construction and operation stage of the proposed tunnels. The
underground strata of these affected lots which lie within the works area
defined as the extent of 10m offset from the outer edge of the Tunnel Section
will be permanently required to form part of TKO-LT Tunnel. The affected lots
include 9 nos. of private lots, 5 nos. of Government STT, 2 nos. of Government
GLA, 3 nos. of TGLA and unauthorized dwellings with approximately 150 people.
Construction of Lam Tin Interchange
2.9.28
The proposed location for Lam Tin Interchange is at the southeast side of
Cha Kwo Ling Hill, immediately north of EHC toll plaza. It is a man-made
three-sided elliptical bowl. The bottom of the bowl comprises a level platform,
about 330m long by 165m across, which is currently occupied by Cha Kwo Ling
Vehicle Deport at the west end and Cha Kwo Ling Nursery at the east end. The platform level is about +6mPD, which is
about the same level as the EHC toll plaza, whereas the steep side-slopes rise
to over +70mPD around the perimeter of the bowl.
2.9.29
The site was originally part of a granite quarry, but in late 1980s the
original void was enlarged to form the casting basin for the immersed tube
tunnels units for the construction of EHC. The side-slopes were cut back and
steepened, and the bottom was excavated down to about -5mPD to accommodate the
flotation of the precast units.
2.9.30
For the recommended option of Lam Tin Interchange, the mainline will be
at the lowest level of about -16mPD, whilst the remaining slip/link roads will
be at higher levels. In order to avoid bulk excavation with excessive cutting
into the hard granite at the bowl bottom, it is proposed to maintain the
platform at about +5mPD with necessary trench excavation for the mainline and
slip/link roads with level lower than +6mPD.
2.9.31
Prior to site formation and excavation works, temporary site access
connecting CKLR to LTI based on the existing road leading to FEHD area should
be firstly formed. This temporary site access will also facilitate construction
of Western Portal and Main Tunnel at Lam Tin side. Site formation for the soil
ground between +6mPD and -5mPD will be excavated by mechanical means; whilst
the rock between -5mPD to -12mPD will be excavated by drill & blast method.
Excavated materials will be disposal off site by barges with destinations
similar to construction of CKL Section. Stage arrangement for haul roads within
the site should be so arranged to suit the site formation works. In view of the
close proximity of Yau Lai Estate, northwest corner of the site would be useful
for sorting and breaking excavated rock prior to disposal to designated
outlets. Temporary noise and air quality mitigation measures would be required
for the site formation works, especially via drill & blast method.
Preliminary blasting assessment will be prepared for ensuring the impacts due
to designed charge-weight, in terms of vibration (ppv) and air-over-pressure
(AOP), on Yau Lai Estate, Sai Tso Wan Landfill, EHC, and other stakeholders
within the influence zone area within the acceptable limits. Monitoring plan
will be prepared as well for ensure adequate control and monitoring for the
concerned stakeholders during blasting.
2.9.32
Excavation by drill and blast is a cyclic procedure. This commences with surveying the blast area,
drilling the blastholes, placing the steel cages and blast screens, charging
the blastholes, placing the surface cover, firing the blast, venting (if
required), removing the protective measures, and then mucking out the blasted
rock. The cycle is then repeated.
2.9.33
The time required to complete one full cycle will be largely dependent on
the size of the blast, as drilling the blastholes and mucking the blasted rock
often take up the majority of the time.
A typical cycle time of 3 to 4 days for any one location within the site
is assumed. It would therefore be necessary
to have at least four active blasting locations within the site to allow blasting
every day. It may also be possible to
blast at more than one location within the site on any one day, provided
sufficient working faces can be created and sufficient protective measures are
available. The maximum number of blast
locations per day would be determined by the Contractor to suit his method of
working.
2.9.34
A four day cycle time would allow survey of the blast area and
preparation of the blast design on day one.
Drilling would be undertaken on day two, and placing protective measures
and blasting on day three. Removal of
the protective measures and mucking would be undertaken on day 4. A single
blast per day is anticipated.
2.9.35
Drilling would be carried out using standard crawler drill rigs, fitted
with dust collection systems and noise mitigation measures. The use of two drill rigs would allow
drilling of two blast areas concurrently, thus potentially reducing the overall
blast cycle time.
2.9.36
Protective measures are anticipated to consist of a surface cover of
gunny sacks, wire mesh and sand bags.
Heavy surface protection of wire mesh covered steel cages are
anticipated to be required on top of the blast area. Heavy rubber mats would also be placed on top
and around the sides of these cages.
Wire mesh covered vertical screens are anticipated to be required to
surround each blast area. Detailed discussions on anti-flyrock measures will be
required by the Contractor with Mines to ensure flyrock occurrences are
eliminated.
2.9.37
Moving and placing of the protective measures is anticipated to be carried
out using a crawler crane. For surface
blasting, every blast may have different depth, width and length, and each
blast will require specific blast design and layout of the protective measures. Typical arrangement of the blast design and
protective measures must be included in the Contractors Method Statement, with
blast specific details provided with each individual blast design submitted to
Mines Division.
2.9.38
Upon completion of site formation works, mainline roadworks, slip/link
roads, viaduct structure, administration building, environmental mitigation
measures will be constructed.
2.9.39
There are 6 slip roads, S1, S2, S3, S4, EHC1 and EHC4 connecting to and
from the main tunnel, Eastern Harbour Crossing and local roads in Kwun Tong
Areas. First of all, permanent
foundation and substructure including all piles, pile caps, pier columns,
abutments and bearings will be constructed.
After that, scaffold and platform propped on the pier heads will be
erected and the deck adjacent to the support will be cast in-situ.
2.9.40
Steel truss with bracket supported on the constructed concrete deck will
then be erected. The platform hanger will also be erected by rods from the
steel truss. Adjacent deck can then be
cast in-situ in span. After concrete strength reach its 7-day value, the
platform, hanger rods, steel truss and brackets will be removed.
2.9.41
To cast the next deck segment, repeat the steps in para. 2.9.39 until
completion of the whole bridge construction.
Construction of administration building/
ventilation buildings and tunnel associated structures
2.9.42
TKO-LT Tunnel’s administration building and the western ventilation
building will be situated at the Lam Tin Interchange whereas the eastern
ventilation building will be situated at TKO portal.
2.9.43
The Ventilation Buildings and Administration Building will be constructed
by typical reinforced concrete construction method which includes i) formwork
and falsework erection, ii) rebar fixing, iii) concrete pouring and curing, and
iv) formwork striking and back propping.
2.9.44
Superstructures will adopt bottom-up construction. Construct ground floor
slabs, beams, columns and walls to the lowest level and process upwards to roof
level.
2.9.45
Other tunnel associated structures, such as pumping stations, garage and
warehouse will be constructed by cast-in-situ method using similar method.
Construction of slopes and retaining walls
2.9.46
Construction of the slopes (including natural terrain mitigation
measures) and retaining walls in this project is to a large extent governed by
the following constraints/uncertainties:
·
Topographical constraint due to sloping ground conditions of the sites;
·
Weather condition;
·
Possible obstructions to the construction; and
·
Geotechnical uncertainties which include ground and groundwater
conditions.
2.9.47
Where possible, construction programme should be arranged so that the
slopes and retaining walls are constructed under favourable weather condition,
preferably in dry season. Temporary drainage system shall be constructed prior
to construction.
2.9.48
Obstructions to construction shall be verified and determined on site.
Utilities and trees shall be properly treated at the onset of the construction.
Natural terrain mitigation measures are normally located at areas with dense
vegetation. Minimal disturbance to the environment shall be maintained during
the construction.
2.9.49
Where existing structures and sensitive receivers are located in the
vicinity of the construction area, temporary safety precaution measures shall
be implemented to avoid possible damage. Instrumentation and monitoring works
shall be implemented throughout the construction period to monitor the effect
of the works. Groundwater monitoring data shall be collected to review the
design groundwater level and hence reduce the geotechnical uncertainties where
necessary.
2.9.50
Cut slopes and temporary cutting for retaining walls shall be formed by
bulk excavation and installed with necessary slope stabilization works
including soil nailing. Slope stabilization works shall be installed and
stability of the excavation shall be maintained at all stages.
2.9.51
Earth filling including construction of fill slopes and backfilling
behind retaining walls shall, in general, be compacted to at least 95% of the
maximum dry density. Surface upon which fill is to be placed should be stripped
of all trees, loose filling, top soil, boulders, debris of any nature and the
like.
2.9.52
L-shaped retaining wall shall not be backfilled until sufficient strength
of concrete has been achieved after concreting. Construction of cantilever retaining walls
shall be completed prior to excavation in front.
2.9.53
Throughout the construction period, all temporary works should be
subjected to regular inspections. Signs of distress in any structure or slope
should be recorded and steps taken to alleviate the distress.
Construction of TKO Interchange
2.9.54
The proposed Interchange comprises of 4 slip roads, i.e. S100, S200,
S300, S400 and the Mainline of Cross Bay Link.
The Slip road S100 will provide traffic linkage in East-North direction,
S200 in West-North direction, S300 in South-West direction and S400 in
South-East direction. In order to
minimize the land-take and visual impact on the nearby sensitive receivers,
e.g. Ocean Shores, small turning radius has been adopted for the slip roads at
some locations. In addition, the
mainline viaducts will provide linkage between the TKO-LT Tunnel
and Cross Bay Link.
Slip
Road Viaducts
2.9.55
Due to the curvilinear nature of the 4 slip roads, the proposed typical
span is set to 40m for end spans and 45m for intermediate spans and the typical
depth of the box section is 2m. The
viaducts are designed to be constructed by cast in-situ method and erected by
balanced cantilever method.
2.9.56
Typical substructure will be formed by monolithic column to the bridge
deck, this will restrict bearing supports at movement joint piers only. The long term maintenance cost of the
viaducts can be reduced as bearing inspection and replacement is a difficult
task, especially when they are located over water.
Mainline
Viaduct Joining Cross Bay Link (CBL)
2.9.57
During the previous meeting with CBL consultants it was agreed that the
typical spans for Cross Bay Link would be 75m, and a 3.5m thick box section
would be adopted. The mainline viaduct
of TKO Interchange will be designed to match with the CBL arrangement as much
as possible. The viaducts would be designed as precast segmental construction
erected by balanced cantilever method.
2.9.58
The typical CBL viaduct shall comprise of 4 box sections, two for the
east & westbound traffic of Cross Bay Link, on the west two additional box
sections are required for slip roads S100 & S300, and on the east
additional box sections required for slip roads S200 & S400. Since the typical spans for the slip roads
are 40m only, the tie-in details between the slip roads and the main viaduct
will need special arrangement, especially on the aesthetic treatment. As agreed with CBL consultants, the columns
for CBL would be typical V-shaped piers and monolithic connection with the
bridge deck.
Foundation
and Substructure
2.9.59
The piers are generally supported on piled foundations designed to suit
the existing geotechnical conditions.
Typically, a group of large diameter bored piles is proposed for each
pier. Where a central pier arrangement is not feasible, eccentric piers or portal
frames will be adopted. Generally, the piles will be socketted into Grade III
or better rock and designed as end bearing piles with capacity contributed from
the rock shaft friction and end bearing capacity of the rock socket. An
external casing will be adopted for marine piles as permanent casing for
casting the piles. For the mainline, the
pile caps will be constructed below sea level and above sea bed level in order
to be consistence with CBL’s. For slip
roads’ pile caps, the caps will be constructed above sea level. The lateral
view of the main bridge piers and slip roads at TKO Section are attached in Appendix
2.3.
Reclamation
for Road P2
2.9.60
Reclamation is required to provide land for construction of Road P2,
Landscape Deck fronting Ocean Shores and at-grade slip roads of TKO Interchange
connecting to Road P2. The reclamation area will also cover the proposed
footpath, cycle track and associated facilities along Road P2 to both CBL and
TKO Town Centre. The reclamation scheme proposed is based on the principle that
the extent of reclamation and dredging is kept to minimum in order to minimize
environmental impact. Besides, the proposed diaphragm walls for cut-and-cover
tunnel construction for the Landscape Deck should no encroach upon the seawall
foundation. Details of the construction
method of the depressed road are reflected in paragraph 2.7.74-2.7.81.
2.9.61
According to the Recommended Scheme of TKO Interchange, the proposed
reclamation will be in a form of strip to bridge the gap between the vertical
seawall fronting Ocean Shores and sloping seawall next to the existing DSD
pumping station at the northern part for construction of the proposed Landscape
Deck; while the southern edge will be extended with sufficient length to allow
the underpass section of Road P2 to climb up and match will corresponding slip
roads of the proposed TKO Interchange.
2.9.62
Follow a series of public engagement activities conducted in late 2010,
majority of the public views supported the Straight Tunnel Option without Toll
Plaza. Under this alignment option, the
extent of reclamation is largely reduced and the required reclamation is
optimized to about 3 ha. The main
purpose of the reclamation area is to provide protection to the depressed road
P2 adjacent to the Ocean Shores and landing area for the elevated slip roads
connecting the interchange with Cross Bay Link.
The general layout of
the reclamation is shown in Figure 2.51.
2.9.63
The existing seabed level of the proposed reclamation area is generally
about -5mPD to –11mPD. The sub-surface profile along the reclamation consists
of a layer of marine deposits (0m to 15m thick) overlying a layer of alluvium
(0m to 8m thick), which is underlain by the completely decomposed rocks (1m to
8m thick).
2.9.64
Sloping seawalls are proposed to surround and support the reclamation. On
one hand, it is proposed for the better dissipation of wave energy and less
wave reflection. On the other hand, it is considered more natural and harmony,
than the vertical blockwork seawall, with the existing natural shoreline along
Chiu Keng Wan.
2.9.65
Steel cellular caisson with stone column is recommended as the
non-dredged method for seawall foundation.
The cellular caisson can provide immediate shear strength to facilitate
early commencement of reclamation behind the seawall. It will be covered by rockfill revetment at
the front and armour protection at the top.
The permanent sloping seawall will be supported by stone column foundation
in the long term by gaining sufficient shear strength during the consolidation
process. The left-in-place cellular
caisson is assumed to be vanished due to corrosion in the permanent case
condition. The cross sections of the reclamation area are shown on Figures
2.52 to 2.56.
2.9.66
It is recommended that general fill is used to form the reclamation. As
the vertical band drains cannot be installed through the general fill, the
vertical band drains must be installed using marine plant before placing general
fill. A geotextile separator and a sand layer about 1.5m to 2m thick need to be
placed on the seabed before installing the vertical band drains.
2.9.67
Rock fill as foundation core will spread the loading intensity downwards
such that the effective maximum pressure at the seawall base level will not be
greater than the allowable capacity of the underlying soils. Ground improvement work using stone column is
recommended to strengthen the marine deposits remained for non-dredged seawall
foundation. Besides, appropriate surface
protection layer should be placed to avoid any scour of the foundation.
2.9.68
On-going settlement of the non-dredged reclamation results predominantly
from the consolidation of the in-situ marine mud and the soft to firm
alluvium. If no ground treatment is
employed, the time required to achieve 90% of residual settlement should take
many years. To accelerate the rate of
settlement, vertical band drains and temporary surcharge technique, using extra
fill material, are normally used.
2.9.69
Band drains should be extended into the underlying firm to stiff alluvial
clay or sand layer to achieve anchorage.
A geotextile layer should be placed directly over the soft ground
followed by a free draining sand layer of 2m to 3m thickness, through which the
pore water pressure within the soft stratum will dissipate. Approximately one-fourth of the total
thickness of marine deposit and reclamation fill. The consolidation period is normally 1
year. However, the exact level of
surcharge and consolidation period shall be determined in detailed design.
2.9.70
Similar to the consolidation using vertical band drains, stone columns
will act as drainage paths and dissipate the excess pore pressure. However, the post construction settlement
will be slightly larger for stone column since more the initial load will
transfer through the columns rather than the soft stratum. Surcharge can be applied to reduce the
residual settlement, if necessary. The
surcharging period will be similar to that of vertical band drains.
2.9.71
Settlement monitoring using geotechnical instrumentation will be required
during the progress of the reclamation in order to establish the settlement
profile and to determine when the surcharge can be removed. Instrumentation shall primarily consist of
settlement markers, placed at the base of the fill prior to commencement of
reclamation, at the top of the fill (or surcharge) and at intermediate levels
where required. Other instruments like
magnet extensometers and piezometers shall be installed in the marine deposits
and underlying strata where such installation would assist in the
interpretation of the results from the settlement markers.
2.9.72
The general construction sequences which can be referred to Figure 2.57,
are summarized as follows:
i.
Plant mobilization for the reclamation works
ii.
Install stone columns at seawall locations
iii.
Install main cell of cellular structure and fill inside the main cell (Refer
to Figure 2.58)
iv.
Repeat (iii) to construct the adjacent main cells of cellular structures
v.
Install connecting arcs between main cells and fill inside connecting
arcs
vi.
Repeat (iii) to (v) above
vii.
Install corrosion protection system
viii.
Construct sloping berm in front of the cellular structures
ix.
Placing geotextile separator and sand drainage blanket if necessary
x.
Installing vertical band drains from marine plant at where no stone
columns are installed
xi.
Filling behind the seawalls for reclamation
xii.
Placing surcharge (Refer to Figure 2.59-2.60)
xiii.
Consolidation period
xiv.
Removal of surcharge
2.9.73
To mitigate pollution of water beyond the works area, the following
working procedure can be applied.
i.
Erect silt curtain to confine the active seawall construction area (Refer
to Figure 2.61).
ii.
Filling for reclamation shall not be carried out unless adequate length
of seawall, say 200m, has been completed ahead of the front end of reclamation
work, thus the seawall can be used as a barrier.
iii.
2m thick sand blanket to be laid above the marine deposits left in place
before commencement of filling for reclamation to eliminate the induced mud
wave due to the filling works.
Construction of Depressed Road P2
2.9.74
Cut-and-cover method will be adopted for the construction of depressed P2
road. Excavation and lateral support
(ELS) works on the reclaimed land are required for excavation and construction
of the underground structure and its foundation. The ELS system typically consists of
temporary retaining structures on both sides of the road supported by
multi-layers of struts. The maximum
excavation depth is approximate 11m for the deepest road level and will be
deepened to 18m locally where close to the underground stormwater pumping
station.
2.9.75
Temporary open cut is considered as the simplest excavation method
provided that the adjacent land is sufficient for slope cutting. However, the Road P2 is located at
reclamation area with high groundwater level.
The control of water tightness during the excavation will be very
difficult for open cut excavation at great depth. It is therefore suggested to limit the depth
to about 3m and keep the excavation level above the sea level for the open cut
excavation method.
2.9.76
For excavation depth greater than 3m, temporary sheet-pile wall would
provide better control of water tightness during the excavation due to its
impermeable surface by interlocking of sheetpiles and the embedment depth to
create groundwater cut-off below the excavation level. The required embedment depth is greater for
excavation at a deeper road level.
2.9.77
Under the current scheme of non-dredged reclamation method, the marine
deposit will be left below the proposed depressed road. For greater excavation depth, the required
embedment depth will be much longer due to the weak strength of marine deposit
in order to maintain the toe stability, and is required to be socketted into
rock for most sections. It is
anticipated that temporary diaphragm wall is required to resist the large
lateral pressure and facilitate the construction of longer embedment depth for
road levels at depth more than 6m below ground.
2.9.78
Therefore, the following temporary excavation and lateral support (ELS)
schemes are anticipated:
2.9.79
Open cut method to be adopted for sections where road levels at 0-3m
below ground;
2.9.80
Sheet-pile wall to be adopted for sections where road levels at 3-6m
below ground; and
2.9.81
Diaphragm Wall to be adopted for sections where road levels at depth more
than 6m below ground.
2.9.82
U-shaped or box structures of the depressed road can be constructed once
the final excavation level is reached.
If required for most section, pre-bored H-piles will be installed before
casting the base slab of the U-shaped structure. The partially complete structure can support
the temporary retaining walls during the strut removal process. Temporary re-propping against the permanent
structure can be provided where necessary until the completion of the depressed
road structure.
Construction of cycle track cum footbridge
at Roads P2/D4 Junction
2.9.83
After the Value Management Workshop held in October 2009 amongst
Government’s departments and the comments received for the Working Paper on
Roads P2/D4 Junction, it is agreed that a cycle track cum footbridge with 2
lifts on each end to be provided at the P2/D4 Road Junction (Southern
Footbridge). A footbridge, namely Northern
Footbridge, will also be constructed to
connect the sport centre at Area 74S and Park Central.
2.9.84
Cast in-situ method will be adopted for both the Southern
Footbridge and Northern
Footbridge.
2.9.85
For the Northern Footbridge, all the sub-structures and foundation will first be constructed. Erection of the falsework and formwork for
the deck construction starting from Park Central will follow. After concreting of the bridge deck, the
falsework and formwork will be dismantled after 7 days of the concreteing and
the falsework and formwork for the next deck between the piers will be
constructed. The construction sequence
will be repeated until all the bridge decks are constructed. Construction of the footbridge’s furniture;
lift tower and staircases will follow.
2.9.86
Construction of Southern Footbridge is similar to Northern Footbridge except that a main arch for the gateway effect will be constructed prior
to the bridge deck construction. For the
main arch, the foundation of the arch will first be constructed. Falsework will be constructed to facilitate
the erection of the steel members for the main arch. In-situ butt welding will be applied to the
steel members to form the main arch.
After the main arch is complete, the piers and bridge decks can be
constructed which is similar to the Northern Footbridge as mentioned above except that cables
between the bridge deck and main arch will be connected during the bridge deck
construction.
2.10.1
The Project construction works are anticipated to
commence in early 2016 with completion of
the Project by end 2020. A preliminary
construction programme for the Project is provided in Appendix 2.1. This programme provides the basis for the assessments
presented in the EIA Report.
2.11.1
Concurrent projects in the vicinity of the Project
site are identified at the following paragraphs. The status of these concurrent projects is
based on the available information at the time of the submission of this
Report. It should be noted that the
implementation of individual projects would be subject to the on-going review
by relevant project proponents.
Trunk Road T2
2.11.2
T2 is a dual two-lane trunk road of about 3.6km, with
2.65km of tunnel. T2, together with the proposed Central Kowloon Route (CKR)
and TKO-LTT will form a new strategic highway network, namely, Route 6.
2.11.3
T2 is a separate DP under the EIAO and hence a
separate EIA Study will be conducted by the project proponent to address all
the impacts (including cumulative impacts) during both the construction and
operational phases.
2.11.4
The T2 project will tie in with the TKO LTT project
and according to the most recent information provided by the T2 project team,
dredging works will take place from early 2016 to mid 2019. Backfilling
works will take place between early 2017 and early 2019. The dredging and
filling programme for T2 would coincide with marine works of TKO-LT Tunnel.
Cumulative air, noise and water quality impacts are therefore expected to be
contributed from T2 during the construction phase of TKO-LT Tunnel and have been addressed in this
EIA. During operation phase, cumulative air quality and noise impacts from
operation of T2 and associated ventilation building are also anticipated and
therefore considered in the assessment in this EIA (Refer to Sections
3, 4 and 5 for further discussion on air, noise and water quality
respectively).
Cross Bay Link (CBL)
2.11.5
CBL is a dual two-lane carriageway of approximately
1.8 km long across the Junk Bay mainly on viaduct, connecting TKO-LT Tunnel to
Wan Po Road at the southeastern part of TKO.
2.11.6
CBL is a separate DP under the EIAO and hence a
separate EIA Study will be conducted by the project proponent to address all
the impacts (including cumulative impacts) during both the construction and
operational phases.
2.11.7
According to the information provided by the CBL
working team, the construction of the CBL is to be implemented in parallel with
the implementation of the TKO-LT Tunnel Project. The Project and CBL is
scheduled to be commissioned together with the rest of Route 6 by the end of
2020.
2.11.8
This would overlap with the
marine works of TKO-LT Tunnel which are proposed to take place between May 2017
and August 2018. Therefore, potential cumulative water quality and marine
ecological impacts during construction phase are anticipated and have been
addressed in this EIA (Refer to Chapter 5 for further discussion on
water quality and Chapter 6 on marine ecology). Construction sites associated with CBL are
located within the study area for air quality impact assessment, however, the
overlapping activities are marine works which would not generate dusty
emissions, cumulative construction air quality impact is not expected. The vehicular emission from CBL has taken
into account of in the operational air quality impact assessment (see Chapter 3 for further discussion on the
air quality). CBL construction site is
beyond the study area of the TKO-LT Tunnel for noise impact assessment.
Cumulative noise impacts from CBL during the construction phase are therefore
not anticipated but the operational traffic noise induced from CBL has been
considered in the cumulative traffic noise impact assessment during operational
phase (see Chapter 4 for further
discussion on noise quality). The
detailed programme and lateral view of CBL is attached in Appendix 2.4.
Shatin to Central Link (SCL)
2.11.9
The Shatin to Central Link (SCL) will be a
through-running line between Tai Wai and the Central Business District of Hong
Kong Island. This new strategic railway corridor will increase significantly
the cross-harbour and Shatin to Kowloon rail capacities and help redistribute
the flows and relieve the other railway lines in Hong Kong and Metro Kowloon.
2.11.10
SCL is a separate DP under the EIAO and hence a
separate EIA Study has been undertaken by the respective project proponent to
address all the impacts (including cumulative impacts) during both construction
and operational phases.
2.11.11
According to information from the project proponent of
the SCL, the project commenced in 2012 and all major construction works are
anticipated to be completed in 2020.
2.11.12
The dredging work for SCL is scheduled from July 2012
to December 2012 for the Kai Tak Runway barging point and also in 2016 for the
submarine railway tunnel from Hung Hom to Admiralty Station. This would overlap
with the marine works programme of CBL.
Hence, the cumulative water quality impacts during the construction
phase of CBL have been considered (see Chapter
5 for further discussion on water quality).
As SCL is not within the study area of TKO-LT Tunnel for air quality and
noise impact assessments, no cumulative air quality and noise impacts are
anticipated during construction and operational phases.
Kai Tak Development – Road D3A & D4A
2.11.13
Road D3A and D4A are both dual 2-lane district
distributor roads, which are 1.4km and 0.1km long respectively, running on the
Runway Precinct of Kai Tak Development (KTD). Road D3A is running along the
centre of the Runway Precinct and is replacing the original southern section of
Road D3 that runs along the waterfront of the Runway Precinct. Road D4 is an
extension of Road D4 connecting to the proposed Road D3A. They will serve the
Cruise Terminal, the Tourism Node and the development sites in the Runway
Precinct.
2.11.14
The construction of these roads will commence in 2014
tentatively and will be completed by 2016, which may not interface with the
construction period of TKO-LT Tunnel. In
addition, these roads are located out of the study area of TKO-LT Tunnel,
therefore, no cumulative environmental impact is anticipated during
construction and operational phases of TKO-LT Tunnel.
Kai
Tak Development - Cruise Terminal
2.11.15
The development of the Cruise Terminal in Kai Tak is
one of the key features in the South East Kowloon Development (SEKD) for
formation of a new tourism, sports and recreation centre in the Metro Area.
2.11.16
According to the EIA report on “Installation of
Submarine Gas Pipelines and Associated Facilities from To Kwa Wan to North
Point for Former Kai Tak Airport Development” (EIA-182/2010), it is planned to
implement the cruise terminal in two phases. Dredging work for Phase I Berth
(the southern portion) was scheduled between 2011 and 2012, and the tentative
programme for Phase II Berth dredging work is planned to be between 2013 and
2014.
2.11.17
No cumulative impact on water quality is anticipated
during the construction phase of TKO-LT Tunnel, but impacts, including
cumulative impact on hydrodynamic regime during the operational phase, have
been considered (see Chapter 5 for
further discussion on water quality).
Tseung Kwan O (TKO) Area 86 Development
2.11.18
TKO Area 86 property development has a site area of
about 33 hectares. The development is expected to comprise some 21,500
flats in 50 residential towers and will be home to a population of 58,000
people. It will also provide retail accommodation of about 50,000 m2
and comprehensive GIC facilities including educational institutes, nurseries,
and a community hall, etc.. The total landscaped area in the development site
will be about 55,000 m2, which includes the Central Park of 19,000 m2.
2.11.19 For Tseung Kwan O (TKO) Area 86 Development, it is out of TKO-LT Tunnel project study area. Therefore, no cumulative impact is anticipated during construction phase.
Submarine Gas Pipelines
2.11.21
According to the EIA report (EIA-182/2010), the
construction would commence in January 2012 and be completed in June 2014.
Dredging is required for the period from April 2012 to December 2012 and
therefore will be completed before the TKO-LT Tunnel works commence. No cumulative construction impact is
expected. Cumulative operational impacts from submarine gas pipelines are also
not expected.
Hong Kong Offshore Wind Farm in Southeastern Waters
2.11.22
With reference to the Project Profile and the EIA
Study Brief (ESB-146/2006), the Project is to construct and operate an offshore
wind farm in Southeastern waters of Hong Kong. The project component includes
an installation of up to 67 wind turbines, an offshore transformer platform,
sub-sea collection and transmission cables, and Research Mast. There will be a
landing cable area and proposed cable at the west of Junk Bay connecting the
collection cables from the turbines and the CLP existing grid connection
network.
2.11.23
According to the latest information provided by CLP,
marine works (including dredging, jetting and suction caisson) for the
construction of the wind farm would be required for the period from January
2017 to September 2017 which would overlap with marine works programme of
TKO-LT Tunnel. Hence, the cumulative water quality impact during construction
phase would need to be considered (see Section
5 for further discussion on water quality).
2.11.24
It is anticipated that the distances from the proposed
cable landing area and cable route in Junk Bay to the identified NSRs and ASRs
for TKO-LT Tunnel project are larger than the 300m and 500m respectively.
Impacts arising from the wind farm construction work in Junk Bay to the NSRs
and ASRs for TKO-LT Tunnel are therefore not expected. Hence construction of
the wind farm would not have any contribution to the cumulative construction
noise and air quality impacts. Cumulative operational impacts from wind farm
are also not expected.
Planning review on Development of ex-Cha Kwo Ling
Kaolin Mine Site
2.11.25
The planning review on development of Ex-Kaolin Mine
Site was commissioned by the Planning Department in July 2011 and is to be read
as an update of the previous feasibility study completed in 2003 by the Civil
Engineer Department (CED). It sets out to examine the viability of private
residential development at the upper platforms of the development site. This
study is set against a background of significant policy changes since the
previous study in 2003. PlanD's recent
public announcement of planning of new developments also includes the Ex-Cha Kwo Ling Kaolin Mine Site (CKLKMS)
as one of the designed land resources for private residential development in
the near future.
2.11.26
The purpose of this study is to devise a development layout
plan that is compatible and cognisant with current and proposed developments in
the area.
2.11.27 The layout plan is
primarily intended to enhance the manner in which the CKLKMS could be utilised
for residential development, the provision of open space, Government,
institution or community (GIC) facilities, and pedestrian circulation network.
This is to formulate under the umbrella of a comprehensive urban design
framework, a landscape framework for private and public spaces and a suggested
implementation strategy for the preferred proposal.
2.11.28
The construction programme of this planning review is
not available at the time of preparation of this Report. Therefore, no
cumulative impact is anticipated during construction phase for TKO-LT Tunnel.
2.11.29
Since this residential development site is located in
the vicinity of TKO-LT Tunnel, operational air quality and noise impacts from
TKO-LT Tunnel on this development are considered in the assessment (see Chapter 3 for further discussion on the air quality and Chapter 4 for further discussion on the
noise).
Yau Tong Bay Redevelopment
2.11.30 The proposed YTB
redevelopment is located in the southern part of East Kowloon on the waterfront
between Kwun Tong and Lei Yue Mun. The Site is surrounded by Cha Kwo Ling Road
and Ko Fai Road. The Eastern Cross Harbour Tunnel is located to the north of
the redevelopment site and to the south of the redevelopment site lies the Yau
Tong Industrial Area.
2.11.31 The overall site
area on the waterfront is approximately 10 hectares. The low rise structures
which were erected on the site in the past such as shipyards, timber yards and
sawmills etc were demolished recently for re-development. There are also an
existing ice making and cold storage factory operated by Dairy Farm, a salt
water pumping station operated by WSD and a site reserved for CEDD’s
maintenance depot which is included as part of the redevelopment site.
2.11.32 The proposed
redevelopment is characterized by an urban development with 14 residential
towers and 4 hotels, together with one G/IC block, clubhouses, retails and
internal roads. A minimum 15m wide promenade will also be provided along the
sea front for recreational use.
2.11.33 The construction works would commence in
early 2013 and to be completed by 2017-2019. It is anticipated that the population
in-take year for the proposed redevelopment would begin around year 2017. It is anticipated that only insignificant
air quality and noise impacts from superstructure construction works from Yau
Tong Bay Redevelopment during overlapping construction period of the Project. Hence, the cumulative air and noise impacts for TKO-LT
Tunnel during construction phase are not anticipated.
2.11.34
Since this residential development site is located in
the vicinity of TKO-LT Tunnel, operational air quality and noise impacts from
TKO-LT Tunnel on this development are considered in the assessment (see Chapter 3 for further discussion on the air quality and Chapter 4 for further discussion on the
noise).
Proposed Residential Site at Kwun Tong
2.11.35
Three pieces of land in Kwun Tong are suggested to be
rezoned as residential lands by Planning Department during Kwun Tong District
Council meeting on 8 January 2013. The details information of these three lands
including the site at Choi Hing Road, Ngau Tau Kok, the site at Pik Wan Road/
Ko Chiu Road Junction and the site at Lei Yue Mun Path, are shown in Appendix 2.5.
2.11.36
These lands are outside the study area of TKO-LT
Tunnel. Therefore, no cumulative impact is anticipated during construction and
operational phases for TKO-LT Tunnel.
2.11.37 No other concurrent
major Government project with programme is indentified at the time of
preparation of this Report. The correspondences from Government departments
advising their status are attached in Appendix
2.6.
2.12.1
Table 2.11 summarises the potential concurrent projects that
would contribute to the cumulative environmental impacts during construction
and/or operational phase.
Table 2.11
Existing and planned concurrent projects
|
Project |
Construction Programme |
Possible Cumulative Impacts |
Considered in the TKO-LTT EIA Study |
||
|
Construction Phase |
Operational Phase |
Construction Phase |
Operational Phase |
||
|
Trunk Road T2 |
To tie in with TKO LTT, between 2016 and
2020 |
Air Quality, Noise, Water quality |
Air Quality, Noise |
Yes |
Yes |
|
Cross Bay Link |
Commence in early 2016, for completion in
late 2020 |
Water quality Marine ecology |
Hydrodynamic
and water quality |
Yes |
Yes |
|
Shatin Central Link (SCL) |
Commenced in 2012 for completion in
2020 |
Nil |
Nil |
Nil |
Nil |
|
KTD – Road D3A & D4A |
Commence in 2014, for completion in 2016 |
Nil |
Nil |
Nil |
Nil |
|
KTD - Cruise Terminal |
Commenced in late 2008 for completion in
2014 |
Nil |
Nil |
Hydrodynamic
|
|
|
Tseung Kwan O Area 86 Development – 33ha |
Commenced
in early 2005 for completion in 2020 |
Nil |
Nil |
Nil |
Nil |
|
Submarine Gas Pipelines |
Commenced
in 2012 for completion in 2014 |
Nil |
Nil |
Nil |
NiL |
|
Hong Kong Offshore Wind Farm in
Southeastern Waters |
Commence in early 2017 for completion in
late 2017 |
Water
quality |
See
Note [1] |
Yes |
No |
|
Planning review on Development of ex-Cha
Kwo Ling Kaolin Mine Site |
Programme is not available |
Nil |
Yes |
Nil |
Yes (as sensitive receivers in the air
& noise impact assessments) |
|
Yau Tong Bay Redevelopment |
Commence
in 2013 for completion in 2017-2019 |
Nil
(Insignificant air quality and noise impacts from superstructure construction
works) |
Yes |
Nil |
Yes (as sensitive receivers in the air
& noise impact assessments) |
|
Proposed Residential Site at Kwun Tong |
Programme is not available |
Nil |
Nil |
Nil |
Nil |
Note:
[1] The wind farm location is outside the
boundary of the water quality model. Therefore the change of hydrodynamic
regime contributed by the wind farm is not considered in Chapter 5, Water
Quality Impact Assessment.