2
Project Description
2.1.2
Traffic congestion has become an increasingly concerning
issue at discrete road junctions and intersections in the North District.
Among the major transport interchanges in the area, Kai Leng Roundabout is one
of the busiest and most important road intersections connecting inter- and
intra-district traffic onto the Fanling Highway. In recent years, public
complaints have been lodged through members of the North District Council (NDC)
on the traffic congestion and recurrent accidents at the Roundabout location.
2.1.3
Media reports had also asserted that the series
of traffic incidents occurred in January 2016, which paralysed and stranded the
District’s external traffic links, was partly due to the traffic gridlock and
overcapacity at this Roundabout and other road junctions in the District. The
traffic chaos appeared in these incidents also highlighted the fragility and
deficiencies of existing transport infrastructure at some locations in the
District where upgrading or improvement works was necessary to rectify the
situation.
2.1.4
To address the above congestion problem, the
Traffic and Transport Committee (T&TC) of NDC has earlier proposed a new North to South Link in an attempt
to mitigate the current traffic situation at Kai Leng Roundabout and Fanling
Highway.
2.1.5
The study area of the proposed new North to South
Link is located in the vicinity of the Kai Leng Roundabout in the North
District. The study area aligns along the So Kwun Po from the south of Pak Wo
Road to the northeast of North District Park,
intercepting the Fanling Highway in the middle portion of the area.
2.1.6
The site was located in cultivated lands based
on the earliest aerial photograph available in Year 1963. Minor building
construction works were gradually carried out between Year 1973 and Year 1982.
The site was a construction site for the connection of Fanling Highway and So
Kwun Po Road between Years 1982 and 1993. The Fanling Highway was commissioned
in Year 1991. Since then, no significant change within the concerned area has
been observed.
2.2.1
As described in Sections 1.1 & 1.2,
the project is designed: -
(a) to provide a new direct road link, referred to as So Kwun Po Link
(SKPL), comprising an at-grade road, an underpass, a single 2-lane flyover
(main ramp) and a single 1-lane flyover (side ramp) connecting San Wan Road on the
north side of SKPL and Pak Wo Road on the south side of SKPIC.
(b) to realign So Kwun Po Road between So Kwun Po Interchange (SKPIC)
and Pak Wo Road;
(c) to modify junctions at San Wan Road and Pak Wo Road; and
(d) to reprovision the affected footpaths, cycle tracks and staircases.
Traffic Condition
2.2.2
SKPIC is a major interchange connecting Sheung
Shui / Fanling area to / from other districts, it is important to ensure smooth
traffic operation of SKPIC. With consideration of the future developments in
North District, the captioned study was carried out to formulate the
improvement scheme – SKPL to ensure the traffic operation of this major
junction.
Provision of SKPL
2.2.3
Currently, there is an indirect link connecting
San Wan Road and Pak Wo Road via Kai Leng Roundabout. Traffic coming from
Fanling Highway westbound (WB), Fanling Highway eastbound (EB) and accessing
either San Wan Road or Pak Wo Road shall be via SKPIC. The proposed new
direct link provides an alternative route between San Wan Road
and Pak Wo Road. Upon commissioning of SKPL under this project, a
portion of traffic between San Wan Road and Pak Wo Road
via SKPIC would be diverted to the new SKPL, and thereby accessibility between
the northern and southern parts of Fanling will be enhanced. In addition,
connectivity of Fanling / Sheung Shui via SKPL will also be enhanced with the
completion of this new link. With the new road link serving as the bypass of
SKPIC for traffic to and from San Wan Road / Pak Wo Road,
the traffic flow of SKPIC will also be reduced.
2.3
Scenario “With” and “Without” Project
Scenario “without” Project
2.3.1
As stated above, the SKPIC has been operating to
its capacity. With the anticipated population growth in the North District
following the completion of the undergoing public and private housing
developments, the traffic condition at SKPIC is anticipated to deteriorate
further. Moreover, some of the major road links and road junctions in Fanling
and Sheung Shui would also experience capacity problems without the Project.
2.3.2
If the Project could be completed and operated
by Year 2031, the capacity problem on traffic flow of the major road links and
junctions in Fanling and Sheung Shui would be relieved or even resolved.
Scenario “with” Project
2.3.3
As the Project will provide an alternative link
for traffic to and from Fanling North and Fanling South, a decrease in traffic
volume of SKPIC and adjacent road links is expected. Also, the modification of
the SKPR at the downstream of SKPL near the south of Pak Wo Road could enhance
its land capacity of the heavily trafficked road between SKPIC and Fanling
South and relieve traffic demand, thereby leading to smoother traffic flows and
a potential reduction in congestion of SKPIC. As a result, the capacity
problem of the critical section of SKPIC would be alleviated and the capacity
of some road junctions would also be improved during peak hours.
2.3.4
Nevertheless, the Project will induce short-term
environmental impacts during construction such as construction noise, dust,
site surface runoff etc.. It is envisaged that with the implementation of
low-noise machinery and good site practices, the construction environmental
impacts could be limited to acceptable levels. It should also be noted that
the works under the Project are designed to avoid impacting the surrounding
residents and users as far as possible.
2.3.5
A summary of the environmental benefits and
disbenefits with and without the Project is provided in Table 2.1.
Table 2.1 Summary of Environmental Benefits and Disbenefits With
and Without the Project
|
Scenarios
|
Environmental
Benefits
|
Environmental
Disbenefits
|
|
With Project
|
·
Noise protection due to direct noise
mitigation measures along SKPL and SKPR will be increased. Existing traffic
noise impacts can be alleviated as much as possible.
·
Provide additional traffic capacities to the
SKPIC to / from San Wan Road and Pak Wo Road, thereby relieving congestion and decreasing the impacts on air
quality and noise along the existing SKPR, San Wan
Road and Pak Wo Road.
|
·
C&D materials will be generated due to the
excavation and lateral support works along the boundary of North District
Park and SKPR (potential for re-use and at other projects).
·
There will be environmental impacts from
construction noise, dust, site surface runoff etc. (implement good site
practices) during construction phase.
|
|
Without Project
|
·
No construction-related environmental impacts
to the surroundings of SKPR, San Wan Road and Pak Wo
Road.
·
No waste will be generated.
|
·
Many of the existing roads in the vicinity of
the Project site are already operating close to or beyond capacity. Traffic
congestion in SKPR, San Wan Road, Pak Wo Road and
other areas in Fanling will continue to worsen.
Environmental impacts, such as air quality and noise will continue to
deteriorate as a consequence.
|
2.4.1
In case the Project could not be proceeded
according to the proposed schedule, SKPIC will be operating over its capacity() in Year 2030. The situation of
traffic congestion will not be improved until SKPL or other traffic measures
are completed and commissioned. With SKPIC operating beyond capacities, longer
traffic queues at Fanling Highway, San Wan Road and Pak
Wo Road will be anticipated, especially during peak
hours, resulting in longer travelling time.
2.4.2
In the absence of the Project, the increased
traffic through SKPIC would overload its road network and cause heavy
congestion. Higher traffic flows through SKPIC will result in greater
environmental impacts on air quality and noise.
2.4.3
If the Project could not be completed and
operated by Year 2031, the capacity problem on the major roads and junctions in
Fanling and Sheung Shui will further worsen.
2.5.1
Construction of the Project is scheduled to
commence in Year 2025 and to be completed before the end of Year 2030. Details
of the construction programme and the measures recommended to be taken during
the construction phase are presented in Section 2.12.
2.6.1
A scheme, hereinafter referred to as the Base
Scheme, was formulated under Agreement No. CE4/2018 – “North-South Link(s) as
Alternative to So Kwun Po (Kai Leng) Roundabouts in North District –
Feasibility Study”. The base scheme has been further refined and developed
under this Consultancy. Description of the base scheme and the developed
scheme of the various road links are given as follows.
General
2.6.2
As described in Section 1.1, the traffic
problems at SKPIC were intended to be resolved by the provision of SKPL
elevated above the existing SKPIC and connecting with San Wan Road on the north
side and Pak Wo Road on the south side.
2.6.3
Starting from the north side, with a view of
achieving the desirable minimum radius of 88m as per the requirement of the Transport
Planning and Design Manual for roads with a speed limit of 50kph, SKPL will
be located on the north side of the existing two ramps connecting San Wan Road,
i.e. existing SKPR / San Wan Road up ramp and down ramp, and SKPR (i.e.
underpass the existing SKPR which is on an embankment). SKPL will connect with
San Wan Road on the west side of the existing SKPR/San Wan Road down ramp in
order to facilitate traffic coming from and heading to MTR Sheung Shui Station
to use SKPL, minimizing the likelihood of SKPL being affected by the potential
tailing back of the SKPIC to San Wan Road. Arrangement of SKPL as described
above will affect the existing footpath and cycle track between North District
Park and the existing two SKPR / San Wan Road ramps. The affected footpaths
and cycle tracks will be reprovisioned by realignment to suit SKPL. The
reprovisioned footpaths and cycle tracks will encroach into the North District
Park and affect the existing skating rink of North District Park. The affected skating
rink will also be reprovisioned.
2.6.4
After the underpass beneath SKPR, SKPL will
start to be elevated to overpass San Wan Road, East Rail Line and then further
elevate to overpass SKPIC, which is a roundabout elevated above Fanling
Highway.
2.6.5
SKPL will reach its highest level at SKPIC.
Also, SKPL will be split into two ramps for connecting with Pak Wo Road, i.e. a
2-lane Main Ramp and a 1-lane Side Ramp. The split-ramp arrangement is to
facilitate the traffic of SKPL to access both bounds of Pak Wo Road and
maintenance of existing traffic movements at the junction of San Wan Road / Pak
Wo Road. The Main Ramp will be a single 2-lane carriageway for traffic from
either bound of Pak Wo Road to access SKPL and the traffic from SKPL to access
Pak Wo Road-WB. The Side Ramp will be a single 1-lane carriageway for traffic
from SKPL to access Pak Wo Road-EB.
2.6.6
With a view of incorporating SKPL and
maintaining all existing traffic movements at the junction of SKPR/Pak Wo Road,
the existing SKPR-NB to SKPIC and SKPR-SB to Pak Wo Road will be split into two
carriageways. The Main Ramp will be sandwiched into the split carriageways of
SKPR. SKPR-SB will be sandwiched between the Main Ramp and the Side Ramp.
2.6.7
The arrangement as described above will involve
multiple phases of traffic movements at the junction of San Wan Road and SKPR.
Maintenance of the existing pedestrian crossing across SKPR will not be
feasible, as multiple staggered crossings will be involved. As a result, the
Scheme involves the provision of a new subway across SKPR to obviate
reprovisioning of the affected pedestrian crossings. The new subway will serve
both pedestrians and cyclists.
2.6.8
The existing junctions of San Wan Road/SKPR and
SKPR/Pak Wo Road will be modified to facilitate the connection of SKPL with San
Wan Road and Pak Wo Road respectively, whilst maintaining all existing traffic
movements.
2.6.9
Further to the base scheme for the SKPL
formulated under Agreement No. CE4/2018 (HY) – “North-South Links as
Alternative to So Kwun Po (Kai Leng) Roundabout in North District – Feasibility
Study”, an alternative road scheme was also developed under this Assignment and
this alternative road scheme is named “Developed Scheme”. A description of the
various scheme options is presented below.
Base Scheme
2.6.10 Basically, the Base Scheme involves the provision of a new road link
connecting San Wan Road on the south side and Pak Wo Road on the north side
above the existing elevated SKPIC and Fanling Highway. The general layout of
Base Scheme is shown in Figure 2.1.
2.6.11 The bridge scheme of Base Scheme is required to overpass the
following existing road links:
·
The existing at-grade Fanling Highways in both
bounds;
·
The existing elevated SKPIC (i.e. HyD Structure
No. N496);
·
The live tracks of East Rail Line;
·
The existing Dongjiang Watermains (DJWM);
·
The existing at-grade slip road from SKPR to
Fanling Highway-EB; and,
·
The existing at-grade slip road from Fanling
Highway-WB to SKPR.
2.6.12 The gradient of Base Scheme will be as high as the proposed SKPL.
SKPL will have to climb and overpass the existing Fanling Highway and SKPIC
within a short distance. It is envisaged that the road gradient of Base Scheme
could be as high as 8.0%, which exceeds the absolute maximum gradient of 8% for
“Trunk Roads, Primary Distributors and Bus Routes” as stipulated in Table
3.3.6.1 of Chapter 3.3 in Transport Planning and
Design Manual, Volume 2. A high gradient of 8.0%
will pose constraints to double-decker buses and may even refrain them from
using the new slip road. However, further shifting the existing slip road of
SKPR/Fanling Highway-EB and/or Fanling Highway-WB/SKPR with a view of reducing
the maximum gradient is highly undesirable as the Fanling Highway might be
realigned for provision of the piers of the proposed SKPL at the existing
central divider of Fanling Highway.
2.6.13 The sharp changes from the horizontal near both upstream and
downstream due to the steep gradient might slightly affect the vertical
sightline of the proposed road link. Hence, the Base Scheme is less desirable.
Developed Scheme
2.6.14 Owing to the issues of the Base Scheme as described above, the
Developed Scheme is formulated and the general layout is presented in Figure 2.2. The main objectives of Developed Scheme are to achieve its key
benefits by overcoming the following issues / problems of Base Scheme:
·
Minimization of the impact on North District
Park and Po Wing Road Playground;
·
Maintenance of the existing at-grade footpath
adjacent to Vienna Garden;
·
Maintenance of the existing southern kerbline of
Pak Wo Road;
·
Interdependence of the structural form, span
length, maximum gradient, pier locations and alignment of SKPL, impacting the
existing SKPR; and
·
Reduction of the maximum gradient of the
proposed SKPL with a view of complying with the absolute maximum gradient of 8%
as stipulated in Table 3.3.6.1 of Chapter 3.3 in Transport
Planning and Design Manual, Volume 2.
2.6.15 The at-grade footpath and cycle track adjacent to Vienna Garden
under the Base Scheme is proposed to be modified to a subway ramp for
connection with the new subway, as the space between the football pitch and
Vienna Garden is insufficient for maintaining the existing at-grade footpath
and cycle track after the addition of the Main Ramp and the Side Ramp of SKPL.
Provided that the existing football pitch and the at-grade footpath shall not
be affected, the existing cycle track along San Wan Road between Ching Hiu Road
and Kat Cheung Crescent will be permanently abandoned.
2.6.16 As the existing cycle track on the south side of Fanling Highway
serves as a parallel and an alternative route for the section of cycle track
affected, abandonment of the section of cycle track would be practical. To
enhance the connectivity of the existing cycle track along Fanling Highway with
the cycle track to be affected, retrofitting of cycle tracks along the section
of Pak Wo Road between Wai Wo Street (adjacent to Sheung Shui Police Married
Quarters) and Po Wing Road Playground, as well as the eastern section of Kat
Cheung Crescent are proposed. As the new subway will be provided only for
pedestrians, provision of ramp for cyclists will be obviated.
2.6.17 With the arrangement of the subway as
described above, i.e. obviation of subway ramp for cycle track and provision of
the staircase and lift at the western end of the subway at the existing
landscaping area, the space will be sufficient for addition of the Main Ramp,
the Side Ramp, the staircase and lift at the eastern end of the new subway,
whilst maintaining the existing football pitch, the pedestrian access (within
the current Government Land Allocation (GLA) for Po Wing Road Playground) of 2m
between the football pitch and the reprovisioned SKPR-NB carriageway, and the
existing footpath of 3m adjacent to Vienna Garden.
2.6.18 As far as the section of the existing cycle
track between Ching Hiu Road and Kat Cheung Crescent will be abandoned, the
space vacated by its abandonment will be sufficient for the maintenance of Eden
Garden with sufficient clear distance, and Pak Wo Road will be maintained.
Thus, environmental impacts to Eden Garden due to the junction improvement will
be minimized.
2.6.19 As compared to the Base Scheme, SKPL above
Fanling Highway and SKPIC is realigned to minimize the bridgeworks above the
existing carriageways to enhance constructability, facilitate optimization of
the span length, and provision of piers at favourable locations, e.g. avoidance
of pier to be located in the central divider of Fanling Highway.
2.6.20 As SPKL will overpass the existing SKPIC which is elevated above the
existing Fanling Highway and be connected to San Wan Road and Pak Wo Road at
the northern and the southern ends respectively in a short distance, the
gradient of the realigned SKPL after the addition of the Main Ramp and Side
Ramp in the Developed Scheme will not exceed an absolute maximum gradient of 8%
as per the requirement of Transport Planning and
Design Manual.
2.7.1
The environmental considerations for scheme
options for SKPL are identified and presented in Table 2.2.
Table 2.2 Summary of Environmental Considerations of the Scheme
Options of SKPL
|
Scheme Options
|
Environmental
Considerations
|
|
Environmental
Benefits
|
Environmental
Disbenefits
|
|
Base Scheme
|
Noise and Air Quality:
·
Adoption of quiet piling method would minimize
the construction noise impact.
Landscape and
Visual:
·
The bridge structure is situated away from
educational institutions and residential blocks of Vienna Garden and Cheerful
Park, hence the visual impact on the residents in the vicinity area is
reduced.
|
Noise and Air Quality:
·
Road sections with steeper gradients would
induce higher vehicular emissions.
Landscape and
Visual:
·
Another layer of bridge construction above the
existing elevated SKPR near Fanling Highway with noise barriers creates a
wall effect and causes intrusive and adverse visual impacts to the Visual
Sensitive Receivers (VSRs) in Sheung Shui / Fanling.
·
The viaduct across Fanling
Highway and elevated SKPR is massive in size and
induces significant visual impacts on the surrounding environment during
operation phase.
Ecological:
·
Potential impact to the ardeid night roosting
site at North District Park would occur during the construction and operation
phase.
|
|
Developed Scheme
|
Noise and Air Quality:
·
New noise barriers will be installed along
SKPL and SKPR. Noise and air quality impacts on the residents of the
buildings close to the SKPL will be reduced during operation phase.
·
Adoption of quiet piling method will minimize
the construction noise impact.
Landscape and Visual:
·
Slip road connecting SKPL to San Wan Road
would induce insignificant visual impacts to the surroundings during
operation stage, particularly for the recreational users of North District
Park.
|
Noise and Air Quality:
·
Due to the aforesaid traffic issues, the
viaduct alignment is unavoidably shifted towards the educational institutions
and residential blocks. Air quality and noise impact on these sensitive
receivers during construction of the slip road (including Excavation and
Lateral Support (ELS) and piling works) would be affected.
·
Noise barriers are required to reduce noise
levels during operation phase.
Landscape and
Visual:
·
The bridge structures situated above the
existing landscape might block some of the sunlight to the greenery and
planting area.
·
The additional layer of bridge construction
above the existing elevated SKPR near Fanling Highway with noise barriers
creates a wall effect and causes intrusive and adverse visual impacts to the
VSRs in Fanling / Sheung Shui.
·
The proposed noise barriers along SKPL and
SKPR will induce visual impacts on the nearby VSRs during operation phase.
Ecological:
·
Potential impact to the ardeid night roosting
site at North District Park would occur during the construction and operation
phase.
|
2.8
Evaluation of the Scheme Options and Selection of the Preferred Option
General
2.8.1
Throughout the evaluation process of the
alignment options for the Project, environmental considerations including air
quality, noise, landscape and visual, and ecological during construction and
operation phase have been thoroughly reviewed and evaluated. Apart from the
environmental considerations, other engineering aspects such as traffic, land
requirement, engineering feasibility, as well as public perception,
construction time and cost, and maintenance requirements, have also been taken
into consideration. The following are the main reasons for selecting the
preferred option.
Developed Scheme of SKPL
2.8.2
The proposed viaduct connecting San Wan Road to
Pak Wo Road is developed to improve the existing traffic conditions of SKPIC
and alleviate the traffic demands at Kai Leng Roundabout and other road
junctions in the North District. Moreover, the impacts that the proposed
viaduct running across Fanling Highway brings to the existing and future
residential buildings are considered acceptable. The installation of noise
barriers along SKPL and SKPR adjacent to the existing educational institutions
and residential blocks would make the traffic improvement scheme more robust
and therefore not appeal to the public, in particular to the local stakeholders
of Fanling / Sheung Shui. The Developed Scheme however may induce medium
visual impacts on the surrounding environment, but would harmonize it as much
as possible.
2.8.3
To maintain daily traffic between the northern
portion and the southern of So Kwun Po, a portion of slip road connecting SKPR
to San Wan Road, Fanling Highway-WB to SKPR, SKPR to Fanling Highway-EB, Pak Wo
Road and San Wan Road would be temporarily diverted and permanently realigned.
Temporary provision of noise screening structures would be required to reduce
the noise levels to the residents of Vienna Garden, Eden Garden, Cheerful Park
and the users of nearby educational institutions.
2.8.4
Encroachment upon the boundary of North District
Park for the construction of the underpass structure and realignment of the
road connecting San Wan Road and SKPL is thus required. In the Developed
Scheme, the extent of such encroachment is further refined to minimize further
adverse landscaping and visual impacts on the recreational users in the
greenery area and the urban park.
2.8.5
The existing skating rink within North District
Park affected by SKPL will be reprovisioned by setting back from SKPL. The
pedestrian access (within the current GLA for North District Park) will
reconnect with the realigned public footpath to suit SKPL. Other than
landscaping aspects, no other existing facilities in the North District Park
adjacent to the existing SKPR/San Wan Road down ramp will be affected.
2.8.6
The proposed viaduct will be above the existing
elevated SKPIC and cause a certain degree of visual obstruction and loss of
views or visual openness due to the proposed viaduct from key public viewing
points.
2.8.7
Although there are some impacts to the residents
and school users nearby during the construction and operation phase of the
Project, these impacts are not insurmountable and would further limit to the
acceptable levels by means of suitable noise mitigation measures taken in
place.
2.8.8
The vertical alignment of the proposed viaduct
descends at maximum allowable gradient when crossing Fanling Highway and East
Rail Line such that the height of the bridge structures could be reduced as
much as possible. The slight reduction in height of the bridge structures
across Fanling Highway and East Rail Line would reduce the visual impact on the
surrounding environment and the nearby VSRs. The environmental impacts on the
nearby residents of the residential buildings, recreational and school users
under the Developed Scheme would be alleviated.
2.8.9
Given the above engineering and environmental
considerations, the new SKPL under the Developed Scheme is selected to be the
preferred option.
Improvement to SKPIC Traffic Condition
2.8.10 The proposed additional
link will provide a new connection between the north and south of Sheung Shui / Fanling to relieve the traffic pressure of SKPIC by diverting the traffic
flow. With the provision of
SKPL, some traffic in the north-south direction of Sheung Shui (especially
traffic to / from MTR Sheung Shui Station and the south of Sheung Shui /
Fanling town) can bypass junctions at San Wan Road and SKPIC. As shown in Figure 2.3, the future traffic condition of SKPIC
will be improved from an overloaded condition to a sufficient capacity, while
the junction of So Kwun Po Road will be further enhanced with more capacities
from the benefit of the proposed SKPL.
2.9.1
At the southern portion of SKPL, a minimum
traffic headroom of 5.1m between the existing road level of SKPIC and the
soffit of the flyover shall be reserved. Cast-in-situ slab on precast beams is
adopted to minimize the required structure depth. Mobile crane would be
deployed to erect the precast beams during non-peak traffic hours with
appropriate Temporary Traffic Arrangements to maintain the traffic flow.
Permanent formworks, e.g. formwork made of fibre-reinforced plastic (FRP) would
be used to construct the cast-in-situ slab. Erection of falseworks to support
the segment erection will not be required. Construction traffic impact will be
minimized.
2.9.2
The bridge deck
structures will be supported by intermediate piers located along the new
alignment. To minimize the extent of diversion / disruption of a variety of
features or utilities both above and below ground, streamlined shape of the
bridge piers will be adopted to reduce modification / diversion of underground
utilities as much as possible.
2.9.3
For the compliance of noise level requirements
to the nearby NSRs in Fanling / Sheung Shui, including Vienna Garden and Sheung
Shui Disciplined Services Quarters, noise barriers on the bridge structures of
the SKPL abutting the adjacent residential blocks would be anticipated.
Nevertheless, the assessment findings of the Traffic Noise Impact Assessment
(see Section 4 of EIA Report) revealed that the operation traffic noise from
existing roads is the dominant source of noise. In order to effectively reduce
the overall traffic noise, it is recommended to apply low-noise road surfacing
(LNRS) to the carriageways of the at-grade roads so that the extent of noise
barriers on the bridge structure would be minimized.
Underpass
2.9.4
The headroom for the underpass at the setting
out line, i.e. centreline of the underpass, is 5.5m, which is sufficient for
provision of the splay on both sides of the top slab and provision of cross
fall of the road surface. The
structural depth of the top slab would be 1m approximately. As the minimum
clearance between the soffit of the top slab of the underpass and SKPR would be
less than 1m, the road level of SKPR above the underpass will be slightly
increased to accommodate the top slab of the underpass. Based on the
information available during the course of the EIA study, it is anticipated
that the maximum increase in road level of SKPR after the completion of the
works would be 500mm approximately.
2.9.5
Cut-&-cover method
will be adopted for the construction of the underpass. SKPR will be
reconstructed based on the designed level in conjunction with the construction
of the underpass.
Depressed Road
2.9.6
A portion of the existing box culvert will be
modified to suit the road realignment of the existing down ramp connecting
SKPIC to San Wan Road and to be structurally capable of withstanding the
additional traffic load.
2.9.7
As the deck will be supported by foundation,
which is independent from the existing box culvert, additional load will not be
imposed on the existing box culvert.
2.9.8
Cut-&-cover method
will be adopted for the construction of the underpass, SKPR will be reconstructed
based on the designed level in conjunction with the construction of the
underpass.
2.10.1 The SKPL connecting San Wan Road and Pak Wo
Road will be in the form of prestressed concrete viaducts. Various methods for
construction of the deck structures, including precast method or cast-in-situ
method have been considered.
2.10.2 Alignment of SKPL shall be determined to
facilitate the adoption of optimized span length and minimize construction
traffic impact. The piers shall be located at the appropriate location in
order to suit the structural form, construction activities and major site
constraints such as major roads and facilities as described above, as well as
the temporary traffic arrangement for construction of the foundation and the
substructure.
2.10.3 As San Wan Road and the existing down ramp
from SKPIC to Fanling Highway-SB are 50m apart, the maximum reach required for
the lifting operation will be 25m approximately. Mobile crane of
super-capacity shall be deployed to undertake the lifting operation.
Availability of such mobile carne is limited in Hong Kong. Time for setting up
and removal of such mobile crane would be long. Consequently, the risk of such
mobile crane to be not available for this project and failure to complete the
lifting operation within the limited non-train hours would be high. In fact,
given that the total length of the elevated road section will be less than 500m
and various types of bridge girder shall be adopted to cater for the varying
geometrical layout, it may not be cost-effective to adopt precast method.
2.10.4 On the other hand, erection of temporary
portal frames across East Rail Line will not be feasible taking account of the
risks and disturbance to the East Rail Line.
2.10.5 Erection of precast segments by launching
girder will not be practical based on the site conditions listed below:
(i)
The launching girder
would be close to or even encroach into East Rail Line. Progress of the works
will be affected as the operation of the launching girder will be restricted to
safeguard operational safety of East Rail Line;
(ii)
Not the entire
underbridge area is accessible for trailers for delivery of the precast
segments necessary for the operation of launching girder;
(iii)
The precast segment can
only be erected one by one. Only one launching girder can be mobilized for
construction of SKPL due to site constraints. Progress of works will be
affected by the operation sequence of the launching girder; and
(iv)
The piers shall be
constructed in sequence from one end towards the other end to suit the
operation of the launching girder. If completion of any piers is delayed, for
example, due to utility diversion, erection of the precast segments for all
piers downstream of the piers in concern will also be delayed, even though the
piers downstream of the piers in concern have been completed.
2.10.6 As launching girder will not be practical
due to site conditions, span by span method will not be feasible either.
Balanced cantilever method shall be adopted for staged cast-in-situ
construction based on the bridge span configuration, except at the end span.
The segments will be progressively cast from the pier head towards the adjacent
piers on both sides in equilibrium.
2.10.7 In case the precast segments will be
erected by mobile crane, temporary road closure shall be implemented for
setting up of plant & equipment, especially the heavy-duty mobile crane,
for erection of the precast segments. The temporary road closure might induce
adverse traffic impacts and high traffic disruption. From the environmental
perspective, construction noise impact will be induced for erection of the
precast segments by mobile crane during the restricted hours.
2.10.8 Taking account of the above, the favourable
method for construction of the concrete box girder across East Rail Line is
cast-in-situ using cantilevered travelling formworks. By adopting cast-in-situ
method using travelling formworks, the segments shall be constructed based on
balanced cantilever. The cantilevered formworks will be erected at the piers
on both sides of East Rail Line, which are all accessible by mobile crane.
2.10.9 The cantilevered formworks will be launched
forward by jacking during non-train hours upon each cantilevered segment is
completed. Repositioning of the formworks by mobile crane will not be
required. After the last cantilever segment on each side is constructed, the
cantilever formworks above East Rail Line will be removed during non-train
hours by mobile crane setting up in San Wan Road.
2.10.10 For cast-in-situ method, the deck structure can either
be constructed on suspended travelling formworks or on ground-supported
falseworks.
2.10.11 For cast-in-situ works on suspended travelling
formworks, balanced cantilever method which is similar to the precast method as
described above shall be adopted, except that the segments will be cast-in-situ
on suspended travelling formworks instead of precast. The cast-in-situ works
can be carried out during non-restricted hours, as logistics of the cast-in-situ
works can be provided via the working space of the existing roads, and the
traffic can be maintained.
2.10.12 Permanent formworks, e.g. formwork made of
fibre-reinforced plastic (FRP), would be used to construct the cast-in-situ
slab. Erection of falseworks to support the segment erection will not be
required. Thus, construction traffic impact will be minimized.
2.10.13 Cast-in-situ on ground-supported falseworks will be
favourable in expediting the construction programme, as the scale of works for
each concrete pour will be increased. Expediting the works is the most
effective means of minimizing the environmental and traffic impacts during the
Construction Phase. Cast-in-situ on ground-supported falseworks is more
environmentally-friendly compared with other methods listed in Table 2.3.
Table 2.3 Environmental
Considerations for Various Construction Methods
|
Construction Methods
|
Precast Method
|
Cast-in-situ Method
|
|
Suspended Travelling
Formworks
|
Ground-supported
Falseworks
|
Night-time construction noise impact
|
The most serious amongst all methods due to heavy lifting
operation during restricted hours.
|
Night-time construction noise impact due to repositioning the
suspended travelling formworks above existing carriageways is not as serious
as precast method.
|
Night-time construction noise impact due to erection of temporary
cross beams above existing carriageways, is not as serious as precast method.
|
Construction site activities and traffic flow
|
The least amount of construction site activities and traffic flow
due to precast segmental construction.
|
The largest amount of construction site activities and traffic
flow due to small scale cast-in-situ works for segmental construction.
|
Moderate amount of construction site activities and traffic flow
due to synergy of larger scale of cast-in-situ works.
|
Environmental Impacts
|
Moderate environmental impact due to moderate duration of works.
|
The most serious environmental impact due to the longest duration of
works.
|
The least environmental impact due to the shortest duration of
works.
|
2.10.14 Based
on the considerations in Table 2.4, cast-in-situ construction method is
the most favourable method for the construction of the elevated SKPL and is
thus considered.
2.11.1 The underpass under SKPR-NB can be
constructed using various tunnelling methods such as cut-and-cover construction
method and drill-and-break / drill-and-blast method. In view of the extent and
geometry of the SKPL alignment, cut-and-cover construction method is considered
a more reliable and controllable approach and is recommended to be adopted as
mentioned in Section 2.9. A comparison of the merits and demerits
between these two construction methods is shown in Table 2.4.
Table 2.4 Considerations for Various
Construction Methods
|
Construction Methods
|
Cut-and-Cover
|
Drill-and-Break /
Drill-and-Blast
|
Merits
|
·
It is a conventional construction method and
requires relatively less special skilled labour force and specialists when
comparing with other construction methods considered.
·
It can facilitate construction of complex
underpass geometry.
·
It can control complex geotechnical conditions
better.
·
It is more flexible for dividing works areas
within the site, thus it can allow flexibility for the contractor to
coordinate with other concurrent projects in the vicinity for arrangement of
respective construction programme to avoid cumulative environmental impacts.
|
·
It can be used for different underpass shapes.
·
It is a fast underpass construction method.
·
Construction work are mainly carried out
underground which can avoid working above ground in some busy urban area.
·
Existing trees and vegetation could be
retained as the construction work will be mainly carried out underground.
|
|
Demerits
|
·
Vibration and settlement to adjacent building
structures, and ground treatment are required to control adverse effects due
to excavation.
·
Land is required for temporary storage of
excavated material to be reused on site.
·
Construction work would be affected by adverse
weather conditions.
·
Removal of existing trees and vegetation for
construction is required, though the affected areas will be reinstated and
replanted.
|
·
Vibration and settlement to adjacent building
structures will be substantial, which is not suitable building structures
with shallow foundations and sites of cultural heritage.
·
High risk for storage and delivery of
explosives to work sites in urban area.
·
It is not suitable for construction work on
soft ground.
·
Noise impact during construction phase will be
substantial.
|
2.12.1 The construction works of the Project will tentatively commence in
Year 2025 and to be completed before the end of Year 2030. A tentative
construction programme for the Project is provided in Appendix 2.1.
2.12.2 To minimize the adverse impacts on the sensitive receivers during
the construction of traffic improvement works to So Kwun Po, the construction
programme and sequence of works will be carefully planned such that the
environmental impacts would be kept to minimum and within acceptable limits.
The following are the measures recommended to be taken during construction
phase:
·
Control of working hours is recommended to
reduce noise impact to the surroundings. No works are to be carried out from
16:30 to 07:30 during dry season (Oct – Mar) and 17:00 to 07:00 during wet
season (Apr – Sep) within 100m from the ardeid night roost site; and to avoid
construction works between 18:00 and 08:00 on weekdays and all hours on Sunday
and Public Holidays within North District Park;
·
Avoid noisy construction activities during
school examination period and schedule construction works as much as possible
during the summer recess for schools and kindergartens in the vicinity of the
construction site, if the programme allows; and
·
Close liaison with the contractors of other
concurrent projects in order to avoid overlapping of construction activities,
and allow sufficient buffer for works at project interface due to possibly
delayed commencement or expedited completion of certain activities in the
programme, so that the cumulative effects of environmental impacts could be
minimized.
2.13.1 Concurrent projects in the vicinity of the Project site are
identified. The status of these concurrent projects is based on the available
information obtained during the course of the EIA Study. It should be noted
that the implementation of individual projects would be subject to further
development and subsequent actions of the respective project proponent.
2.13.2 The locations of these planned / committed projects, which potential
cumulative environmental impacts may arise during the construction and
operational phases, are shown in Figure 2.4, of which the key details of these projects which may bear cumulative impacts
during construction phase in its vicinity are summarized in Table 2.5.
Cumulative impacts from the concurrent projects have been assessed in the
individual sections of this EIA Report.
|
Project
|
Project
Proponent
|
Construction
Period
|
|
Housing
Development in
Ching Hiu Road
|
Civil
Engineering and Development Department (CEDD) /
Housing Department (HD)
|
2022
to 2030
|
|
Housing
Development in
Fanling Area 17
|
CEDD
/ HD
|
2023
to 2031
|
|
Expansion
of North District Hospital
|
Architecture
Service Department (ArchSD) /
Hospital Authority (HA)
|
2021
to 2028
|
|
Utilities
Works and Junction Improvement Works for Partial Development of
Fanling Golf Course Site
|
CEDD
|
2024
to 2029
|
|
Reclaimed
Water Supply to
Sheung Shui and Fanling
|
Water
Supplies Department (WSD)
|
2021
to 2026
|
2.14.1 The Project Profile (PP-616/2021) was submitted to the Environmental
Protection Department (EPD) on 6 January 2021 and was exhibited for public
inspection between 7 January 2021 and 20 January 2021.
2.14.2 During the exhibition period, public comments on the Project Profile
were received and mainly focused on observations of the existing traffic conditions,
suggestions on additional traffic aids or modifications to alleviate the
situation, nuisance of noise, construction impacts to the egretry at a pond in
North District Park and surrounding environments, extent of tree felling, and
preservation of the habitat. The construction
programme has been optimised based on the suggestions received during the
public inspection, such as minimisation of heavy construction works near
North District Park during ardeids’ breeding season, and implementation of practical
mitigation measures to reduce the construction impacts and the likelihood of
bird collision. The aforementioned potential impacts have been addressed in Sections
3 to 10.