2.6 Consideration of Alternative Options
2.9 Construction Method and Engineering
Requirements
LIST OF TABLES
Table 2-1 Consideration
on Permanent Traffic Arrangement
Table 2-2 Consideration on Alignment Design
Standard
Table 2-3 Consideration on Traffic Impact at
Construction Stage
Table 2-4 Consideration on Other Operational
Factors
Table 2-5 Consideration on Bridge Scheme
Table 2-6 Consideration on Noise Mitigation
Measure
Table 2-7 Consideration on Bridge Scheme
Table 2-8 Consideration on Other Elements
Table 2-9 Consideration on Land Requirement
Table 2-10a Consideration on Environmental Impact
Table 2-10b Rankings
of Factors of Environmental Impacts
Table 2-11 Consideration on Capital and Recurrent
Cost
Table 2-12 Consideration on Maintenance
Consideration
Table 2-13 Consideration on Time for Completion
Table 2-14 Overall Marking and Overall Ranking for
Identified Options
Table 2-15 Major Concurrent Projects
LIST OF FIGURES
Figure 2.1 Proposed
Road Works
Figure 2.2 Sections
of Proposed Road Works
Figure 2.3 Option
1: Separate Viaduct on East Side of TWR (design speed 50 km/h)
Figure 2.4 Option
1A: Separate Viaduct on East Side of TWR (design speed 70 km/h)
Figure 2.5 Option
2: Separate Viaduct on West Side of TWR (design speed 50 km/h)
Figure 2.6 Option
2A: Separate Viaduct on West Side of TWR (design speed 70 km/h)
Figure 2.7 Option
2B: Separate Viaduct on West Side of TWR and merging nearside lane of TWR with
KCR Upramp (design speed 70 km/h)
Figure 2.8 Option
3: Widening along both Nearside and Offside Lanes of TWR (design speed 70 km/h)
Figure 2.9 Option
3A: Widening along both Nearside and Offside Lanes of TWR and Merging Nearside
Lane of TWR with KCR Upramp (design speed 70 km/h)
APPENDICES
Appendix 2-1 Tentative
Construction Programme
· Existing footbridge NF303 is to be
demolished and be re-provided;
· Existing Public Works Regional
Laboratory will be affected;
· Existing drainage reserve zone
positioned alongside TWR will be affected;
· Existing bus stop outside subway NS10A is to be relocated; and
· Minor modification to the existing KCR involves removal of the existing planter, breaking and reinstating KCR with the new road marking.
· Option 1: Separate Viaduct on East Side of TWR (Design Speed 50km/hr)
· Option 1A: Separate Viaduct on East Side of TWR (Design Speed 70km/hr)
· Option 2: Separate Viaduct on West Side of TWR (Design Speed 50km/hr)
· Option 2A: Separate Viaduct on West Side of TWR (Design Speed 70km/hr)
· Option 2B: Separate Viaduct on West Side of TWR and Merging Nearside Lane of
TWR with KCR Upramp (Design Speed 70km/hr)
· Option 3: Widening Along Both Nearside and Offside Lanes of TWR (Design
Speed 70km/hr)
· Option 3A: Widening Along Both Nearside and Offside Lanes of TWR and Merging
Nearside Lane of TWR with KCR Upramp (Design Speed 70km/hr)
This option introduces an
additional southbound lane from KT I/C upramp which connects to the existing
downslope segment of KCR upramp.
Currently, KCR upramp has a single traffic lane and is dedicated to
Route 3 traffic, connecting KT I/C upamp to KCR
upramp lane will require allowing non-Route 3 traffic leaving KCR upramp
lane. This is currently not allowed.
This option is illustrated in Figure 2.3. Results from the traffic survey undertaken
have indicated that the KCR upramp lane has v/c ratios of 0.26 and 0.27 for am peak and pm peak respectively. The basis of the design
for this option is to utilize the remaining capacity available on the KCR
upramp lane.
The space available at the gap
between piers D8 and D9 of Tsing Kwai Highway (TK H/W) elevated road is a
constraint to the width of KT I/C upramp structure. A viaduct structure with
design speed of 50km/hr can readily meet the horizontal clearance requirement.
The design speed of 50km/hr is in compliance with Transport Planning and Design
Manual (TPDM) requirement for slip roads, however, the speed limit on KCR
upramp will need to be reduced to 50km/hr (from the current 70km/hr) to match
KT I/C upramp, up to the straight section of KCR upramp where it runs parallel
to the three lanes of TWR. In addition,
weaving movement (over approximately a 300m length) will have to be allowed to
enable destination selection.
This
option is similar to Option 1 except the design speed of 70km/hr is adopted and
consequently a wider road width on the curved section of the viaduct is
required to achieve the required sight distance. Widening of TWR on the west side is also
required. This option is illustrated in Figure
2.4.
As
compared with Option 1, a longer taper is required at the merge with KCR upramp, consequently only about 215m length (compared to
300m in Option 1) is available for weaving movement before the junction with
Route 3 upramp.
This option introduces an
additional southbound lane on the west side of TWR and this lane is connected
to the existing lane on the west side of KCR.
This option is illustrated in Figure
2.5. Results from the traffic survey
undertaken have indicated that the two segregated lanes on the west side of KCR
have v/c ratio of 0.32 and 0.40 for am peak and pm
peak respectively. The basis of design
for this option is to utilize the remaining capacity currently available on the
two segregated.
A separate viaduct structure with
design speed of 50 km/hr on the west side of TWR is proposed. The space
available at the gap between piers D6 and D7 of TK H/W elevated road is a
constraint to the width of the viaduct structure. The design speed of 50km/hr for the
additional lane meets TPDM slip road standard.
This design speed will have to be maintained at 50km/hr up to the
position where the lane merges with the adjacent lanes of KCR. A second structure (150 m in length) along
the nearside lane of TWR near existing KT I/C upramp is required to achieve
widening at the east side of TWR.
This is the preferred option for
this Project. This option is similar to
Option 2 except the design speed is 70km/hr and a wider road width is provided
due to the need for longer sight distance. An
additional southbound lane is introduced on TWR and this lane is carried
through to KCR. The two segregated lanes
on the west side of KCR are to be merged into one to enable this arrangement.
This option is illustrated in Figure 2.6.
Similar to Option 2, a second
structure (150 m in length) along the nearside lane of TWR near existing KT I/C
upramp is required to achieve widening at the east side of TWR.
The main difference of this option
from Option 2A is that the segregated lanes on the west side of KCR will not be
affected, and that the TWR nearside lane from KT I/C upramp is connected to the
existing downslope segment of KCR upramp.
This option is illustrated in Figure
2.7. The basis of design for this
option is to utilize the remaining capacity available on the KT I/C upramp
lane. Results from the traffic survey
undertaken have indicated that the KCR upramp lane have v/c ratio of 0.26 and
0.27 for am peak and pm peak respectively.
Similar to Option 2, a second
structure (approximately 150 m in length) along the nearside lane of TWR near
existing KT I/C upramp is required to achieve widening at the east side of
TWR.
This option introduces an
additional southbound lane on TWR and this lane is carried through to KCR. The two segregated lanes on the west side of
KCR are to be merged into one so that one traffic lane is available for
connection to the additional southbound lane on TWR. This option is illustrated in Figure 2.8. The basis of design for this option is to
utilize the remaining capacity available on the two segregated lanes on
KCR. Results from the traffic survey
undertaken have indicated that the two segregated lanes on KCR have v/c ratio
of 0.32 and 0.40 for am peak and pm peak
respectively, i.e. there is spare capacity of over one traffic lane.
Widening structures are proposed
along both edges of the existing TWR.
Designed for design speed of 70km/hr, which matches current TWR, the
widening structures meet the horizontal clearance requirement between piers D7
and D8 of TK H/W elevated road.
The main difference of this option
from Option 3 is that the segregated lanes on the west side of KCR will not be
affected, and that the TWR nearside lane from KT I/C upramp is connected to the
existing downslope segment of KCR upramp.
This option is illustrated in Figure
2.9. The basis of design for this
option is to utilize the remaining capacity available on the KCR upramp
lane. Results from the traffic survey
have indicated that the KCR upramp lane have v/c ratio of 0.26 and 0.27 for am peak and pm peak respectively.
Widening structures are proposed
along both edges of the existing TWR.
Designed for design speed of 70km/hr, which matches current TWR, the
widening structures meet the horizontal clearance requirement between piers D7
and D8 of TK H/W elevated road.
· For option that introduces
weaving, weaving analysis based on preliminary traffic forecast;
· Compliance with TPDM standards;
and
· Feasibility assessment on the
proposed bridge scheme.
(I) Permanent Traffic Arrangement
The road improvement scheme is to provide an additional traffic lane
for the southbound traffic between KT I/C upramp and KCR. The critical factors that would affect
permanent traffic arrangement are:
(i)
With
the number of traffic lanes on KCR fixed, the reserve capacity of the existing
lane will be critical to the performance of the improvement scheme.
(ii)
Change
to current traffic arrangement.
The factors taken into consideration in comparison of the options are
described in the table below with the ranking determined accordingly:
Table 2-1 Consideration on Permanent Traffic Arrangement
Option |
Factors |
*Ranking |
2 |
(i)
This option requires the segregated
lanes on KCR be merged prior to the introduction of the additional lane from
the Project. From the conducted
traffic survey, the respective v/c ratio for the two segregated lanes on KCR
was 0.32 and 0.40 for the am and pm peak respectively. Capacity of more than one traffic lane is
anticipated to be available. (ii)
Merging the original two segregated
lanes on KCR to one lane. Based on v/c
ratio, impact to traffic should be minimal. |
1 |
2A |
(i)
Identical to Option 2. (ii)
Identical to Option 2. |
1 |
3 |
(i)
Identical to Option 2. (ii)
Identical to Option 2. |
1 |
3A |
(i)
This option converts the existing
downslope segment of KCR Upramp lane as continuation of the additional lane
and uses up its remaining capacity.
From the conducted traffic survey, the respective v/c ratio was 0.26
and 0.27 for the am and pm peak respectively.
Capacity of less than one traffic lane is therefore anticipated to be
available. (ii)
(a) A merge is introduced from the KCR
upramp to TWR sacrificing the original priority of traffic destined for Route
3. (b) In this option, early lane
selection for TWR traffic is required for traffic destined for Route 3. |
2 |
*
Ranking: 1 = most preferable & 2 = least preferable under this viewpoint
(II) Alignment Design Standard
According to TPDM, TWR and KCR are urban trunk roads which should have
design speed of 80km/hr. Due to the site
constraints, design speed is to match with the existing speed limit (70km/hr)
on TWR and KCR. Comparisons among the
options are therefore made to the corresponding alignment design standard and
summarised in below table.
Table 2-2 Consideration on Alignment Design Standard
Alignment
Design Standard |
Option 2 |
Option 2A |
Option 3 |
Option 3A |
||
(i) |
Design Speed |
70km/h for existing TWR/KCR |
50 km/h |
70 km/h |
70 km/h |
70 km/h |
(ii) |
Lane Width |
3.65m (minimum) |
4.0m |
4.0m |
4.0m |
4.0m |
(iii) |
Horizontal Curve |
TPDM Vol. 2 Cl. 3.3.3.1 175m(R3) Desirable – 70km/hr 88m (R1) Absolute – 70km/hr |
219.6m> R3 |
219.5m> R3 |
168.5m> R1 |
175m=R3 |
(iv) |
Superelevation |
TPDM Vol. 2 Cl. 3.3.3.3 7% for curve of radius < R4 10% for R3 radii or less |
7% |
10% |
10% |
10% |
(v) |
Sight Distance |
TPDM Vol. 2 Cl. 3.3.5 120m Desirable 90m Absolute |
50m |
90m |
90m |
90m |
(vi) |
Vertical Gradient |
TPDM Vol. 2 Cl. 3.3.6 4% Desirable 8% Absolute |
10% |
8% |
6% |
6% |
(vii) |
Vertical Curve (Crest) minimum K value |
TPDM Vol. 2 Cl. 3.3.7 K=30 Desirable (70m/hr) K=17 Absolute (70m/hr) |
K=6.5 |
K=17.0 |
Match existing TWR |
Match existing TWR |
(viii) |
Vertical Curve (Sag) minimum K value |
TPDM Vol. 2 Cl. 3.3.7 K=20 Desirable (70m/hr) K=20 Absolute (70m/hr) |
K=13.0 |
K=20.0 |
Match existing TWR |
Match existing TWR |
(ix) |
Merging Length |
TPDM Vol. 2 Cl. 4.8.6.12 60m nose + 150m taper |
{Not applicable} |
{Not applicable} |
{Not applicable} |
60m nose + 150m taper |
|
|
*Ranking |
3 |
1 |
2 |
1 |
Note: Items complying with the design standard are underlined. * Ranking: 1 = most preferable & 3 =
least preferable under this viewpoint.
(III) Traffic Impact at Construction Stage
In the construction stage, there would be impact, arising from both the
construction activities as well as the additional construction traffic, to road
traffic in the Project area. Detailed
evaluation and assessment with recommendation on the appropriate temporary
traffic management scheme or other mitigation measures would be included under
the construction traffic impact assessment in the TIA Report. Comparison of different impacts arising from
construction of major items of Works in the options have been conducted
Traffic through the existing road system in TWR should basically be
maintained during the construction stage.
Impacts to the following major roads in the Project area are considered
in turn:
(i)
Tsuen
Wan Road
(ii)
Kwai
Chung Road
(iii)
Kwai
Chung Road Upramp
The factors taken into consideration in comparison of the options are
described in the below table with the ranking determined accordingly.
Table 2-3 Consideration on Traffic Impact at Construction Stage
Option |
Factors |
*Ranking |
2 |
(i)
Considerable
impact to traffic on TWR is anticipated due to the very long stitched joint
between Grid E1 & E6. Minor impact
for the very localized stitched joint between Grid F1 & F3. (ii) There would be some impact during construction of
the Grid F8 abutment. Considerable
impact to traffic on KCR for realignment of this road. Some impact is anticipated for demolition
of footbridge NF303 and for reconstruction. (iii) No impact. |
1 |
2A |
(i)
Considerable impact to traffic on TWR
is anticipated due to the very long stitched joint between Grid G1 &
G6. Minor impact for the very
localized stitched joint between Grid H1 & H3. (ii)
There would be some impact during
construction of Grid H7 foundation and Grid H8 abutment. Considerable impact to traffic on KCR for
realignment of this road. Some impact
is anticipated for demolition of footbridge NF303 and for its reconstruction. (iii)
No impact. |
2 |
3 |
(i)
Considerable impact to traffic on TWR
is anticipated due to the very long stitched joint between Grid J1 &
J8. Considerable impact is also
anticipated for the very long stitched joint between Grid K1 & K6. High impact during construction of NMM. (ii)
There would be some impact during
construction of Grid K5 foundation and Grid K6 abutment. Considerable impact to traffic on KCR for
realignment of this road. Some impact
is anticipated for demolition of footbridge NF303 and for its reconstruction. (iii)
High impact during construction of
NMM. |
3 |
3A |
(i)
Considerable impact to traffic on TWR
is anticipated due to the very long stitched joint between Grid L1 &
L8. Considerable impact is also
anticipated for the very long stitched joint between Grid M1 & M6. High impact during construction of NMM. (ii)
There would be some impact during
construction of Grid M5 foundation and Grid M6 abutment. Considerable impact to traffic on KCR for
realignment of this road. Some impact
is anticipated for demolition of footbridge NF303 and for its reconstruction. (iii)
High impact during construction of
NMM. |
3 |
*
Ranking: 1 = most preferable & 3 = least preferable under this viewpoint
(IV) Other Operational Consideration
Within the Project area, there is a bus stop originally located in
front of a pedestrian subway (NS10A) which is now mainly serving the residents
of Lai King Estate. It would be affected during construction and after the
proposed flyover will be built.
Requirement of relocation is the critical issue on operational
consideration.
The factors taken into consideration in comparison of the options are
described in the below table with the ranking determined accordingly.
Table 2-4 Consideration on Other Operational Factors
Option |
Factor (I) |
*Ranking |
2 |
Require
relocation. |
2 |
2A |
Require
relocation. |
2 |
3 |
Require
relocation. |
2 |
3A |
No
relocation required. |
1 |
*
Ranking: 1 = most preferable & 2= least preferable under this viewpoint
(V) Bridge Scheme
The comparison is concentrated on the design of the bridge
schemes. The critical factors to be
considered are:
(i)
The
design should minimize the impact on existing and, in particular, lowering the
risk and uncertainties associated with any required strengthening of the
structure.
(ii)
The
design should minimize the impact on Tsing Kwai Highway (TK H/W) elevated road
and, in particular, lowering the risk and uncertainties associated with any
required reconstruction of its bridge pier(s).
(iii)
The
design should maintain adequate horizontal and vertical clearance to existing
structures.
The
factors taken into consideration in comparison of the options are described in
the following table with the ranking determined accordingly.
Table 2-5 Consideration on Bridge Scheme
Option |
Factors |
*Ranking |
2 |
(i)
Bridge E is stitch joined (whole
length) to existing TWR flyover by the nearside lane. There could be need to strengthen existing
TWR flyover. Bridge F is a separate
bridge structure. A short stub end
between Grid F1 & F2 is stitched to existing TWR flyover, but impact on
it is very low. (ii)
No reconstruction required on TK H/W
piers. (iii) Bridge
E: 5.11m vertical clearance to MTRC viaduct.
Bridge F: 6.06m & 0.66m horizontal clearance to TK H/W pier D6 and
D7 respectively. 6.60m vertical
clearance to TK H/W viaduct. |
1 |
2A |
(i)
Bridge G is stitch joined (whole
length) to the existing upramp by the nearside lane. There could be need to strengthen the
existing TWR flyover. Bridge H is a separate bridge structure. A short stub end between Grid H1 & H2 is
stitched to the existing TWR flyover, but impact on it is very low. (ii)
No reconstruction required on TK H/W
piers. (iii)
Bridge G: 5.11m vertical clearance to
MTRC viaduct. Bridge H: 2.3m
horizontal clearance to TK H/W pier D7.
7.18m vertical clearance to TK H/W viaduct. |
2 |
3 |
(i)
Bridge J is stitch joined (whole
length) to the existing TWR flyover by the nearside lane while Bridge K is
stitch joined (whole length) to the existing TWR flyover by the offside
lane. There could be a need to strengthen
the existing TWR flyover. (ii)
No reconstruction required on TK H/W
piers. (iii)
Bridge J: 5.11m vertical clearance to
MTRC viaduct. Bridge K: 0.69m
horizontal clearance to TK H/W pier D7.
7.53m vertical clearance to TK H/W viaduct. |
3 |
3A |
(i)
Bridge L is stitch joined (whole
length) to the existing TWR flyover by the nearside lane while Bridge M is
stitch joined (whole length) to the existing TWR flyover by the offside
lane. There could be a need to strengthen
the existing TWR flyover. (ii)
No reconstruction required on TK H/W
piers. (iii)
Bridge L: 5.11m vertical clearance to
MTRC viaduct. Bridge M: 0.69m
horizontal clearance to TK H/W pier D7.
7.53m vertical clearance to TK H/W viaduct. |
3 |
*
Ranking: 1 = most preferable & 3 = least preferable under this viewpoint
(VI) Noise Mitigation Measure (NMM)
The comparison is focused on the design of the noise mitigation
measures. The critical factors to be
considered are:
(i)
The
design should minimize the impact on existing TWR flyover and, in particular,
avoid additional loading put on this structure which was completed under
earlier design standards.
(ii)
The
design should minimize impact to traffic on adjacent roads and to other
elements such as roadside slopes.
(iii)
Construction
complexity.
The
factors taken into consideration in comparison of the options are described in
the following table with the ranking determined accordingly:
Table 2-6 Consideration on Noise Mitigation Measure
Option |
Factors |
*Ranking |
2 |
(i)
The NMM extends beyond
the new bridge onto the new abutment.
There would be no impact on existing TWR flyover. (ii)
The NMM can be constructed from the new
bridge and from the new abutment. Minimal impact on adjacent roads
and other elements. (iii)
The NMM is spanning approximately 7m over
the new lane. Construction complexity
is low. |
1 |
2A |
(i)
The NMM extends beyond
the new bridge onto the new abutment.
There would be no impact on the existing TWR flyover. (ii)
The NMM can be constructed from the new
bridge and from the new abutment. Minimal impact on adjacent roads
and other elements. (iii)
Due to the wider bridge, the required span
of the NMM is approximately 10m. The
required extent is also longer than Option 1A. |
2 |
3 |
(i)
The NMM over both the
new lane and the existing lanes of TWR.
Support from existing TWR flyover would be required. Strengthening of TWR flyover is very likely
required. High impact on existing TWR
flyover. (ii)
Support (columns & foundations) would
be required to be constructed on the roadside slopes in front of Fung King
House. Also, construction over
existing roads will be required.
Disturbance to existing traffic is unavoidable. High impact is anticipated on adjacent roads and other
elements. (iii)
The NMM is spanning over 5 lanes requiring
a span of over 20m. Construction
complexity is much higher than other options. |
3 |
3A |
(i)
The NMM over both the
new lane and the existing lanes of TWR.
Support from existing TWR flyover would be required. Strengthening of TWR flyover is very likely
required. High impact on existing TWR
flyover. (ii)
Support (columns & foundations) would
be required to be constructed on the roadside slopes in front of Fung King
House. Also, construction over existing
roads will be required. Disturbance to
existing traffic is unavoidable. High impact is anticipated on adjacent roads and other
elements. (iii)
The NMM is spanning over 5 lanes requiring
a span of over 20m. Construction
complexity is much higher than other options. |
3 |
* Ranking: 1 = most preferable & 3 =
least preferable under this viewpoint
(VII) Utilities and Drainage Impact
In construction stage especially foundation construction, there would be
impact to the utilities in the Project area. Permanent diversion and local
realignment of the existing utilities would be required. The existing utilities
potentially to be affected include drainage and sewage system, electrical power
supplies, watermains, lighting systems and telecom
utilities. For other underground obstructions such as the box culvert and the
foundation of existing bridges, no significant difference is anticipated among
the options. Comparisons among the options are made based on the major impacts
identified in the UIA Report under this Project as below:
(i)
There
are high voltage power cables i.e. 132kV laid under the footprint of the
proposed alignment options and would be affected during foundation
construction.
(ii)
Piers
and foundation will be located within the drainage reserve which requires
seeking agreement from DSD.
The factors taken into consideration in comparison of the options are
described in the below table with the ranking determined accordingly:
Table 2-7 Consideration on Bridge Scheme
Option |
Factor |
*Ranking |
2 |
(i)
132kV cable near Grids E1 to E5, F3
piers & F8 abutment (6 piers + abutment wall) (ii)
2 piers (Grid E4-E5) located within drainage
reserve. Impact is considered as minor. |
1 |
2A |
(i)
132kV cable near Grids G1 – G5, H3
piers & H8 abutment (6 piers + abutment wall) (ii)
2 piers (Grid G4-G5) located within
drainage reserve. Impact is considered as minor. |
1 |
3 |
(i)
132kV cable near Grids J1 – J5, J7,
K1, K2 piers & K6 abutment (8 piers + abutment) (ii)
2 piers (Grid J4-J5) located within
drainage reserve. Impact is considered as minor. |
2 |
3A |
(i)
132kV cable near Grids L1 – L5, L7,
M1, M2 piers & M6 abutment (8 piers + abutment) (ii)
2 piers (Grid L4-L5) located within
drainage reserve. Impact is considered as minor. |
2 |
* Ranking: 1 = most preferable & 2 =
least preferable under this viewpoint
(VIII) Impact on Other Elements
The existing footbridge NF303 currently
serves as a main access for pedestrians crossing KCR. Under some of the road
improvement options, this footbridge NF303 would be modified or reconstructed.
Moreover, there is a pedestrian subway (NS10A), providing access under KCR to
Lai King Estate. The subway would be required to be extended to cater for
widening the KCR downramp.
The ranking factors to be considered on
other main elements affected by the Project would be as shown below:
(i)
Footbridge
NF303: For comparison purpose, the surface area of proposed reconstructed
footbridge [Afootbridge] was estimated for each
option.
(ii)
Subway
NS10A: For comparison purpose, the surface area of proposed extension to subway
[Asubway] was estimated for each option.
The factors taken into consideration in comparison of the options are
described in the below table with the ranking determined accordingly:
Table 2-8 Consideration on Other Elements
Option |
Factor
(i) [Afootbridge] |
Factor
(ii) [Asubway] |
*Ranking |
2 |
440 sq m |
Nil |
1 |
2A |
440 sq
m |
Nil |
1 |
3 |
440 sq
m |
15 sq
m |
3 |
3A |
440 sq
m |
9 sq
m |
2 |
* Ranking: 1 = most preferable & 3 = least preferable under this
viewpoint
(IX) Land Requirements
Based on the latest land status plan, all
proposed works in the seven options are either within Government land lots or
public roads. The major lands to be affected in the Project area and its status
are listed as follows:
(i)
The
amount of land (otherwise available for other use) sterilized by works under
this Project. For comparison purpose,
the area within land lots [Alot] was estimated for
each option.
- Lot No. STT3706K&T STT: Short term tenancy for car parking use
- Lot No. GLA-TKT 1726 TGLA: Temporary
Government land allocation to Public Works Laboratory until 23 June 2016
(ii)
The
impact on the existing feature, i.e. Public Works Laboratory within Lot No.
GLA-TKT 1726 TGLA (in terms of the two buildings’ footprint) in the construction
stage of the Project.
The factors taken into consideration in comparison of the options are
described in the below table with the ranking determined accordingly:
Table 2-9 Consideration on Land Requirement
Option |
Factor
(i)[Alot] |
Factor
(ii) |
*Ranking |
2 |
1810 sq
m (535 sq
m of Lot No. STT3706K&T STT and 1275 sq m of Lot No. GLA-TKT 1726 TGLA) |
Affected |
3 |
2A |
1810 sq
m (535 sq
m of Lot No. STT3706K&T STT and 1275 sq m of Lot No. GLA-TKT 1726 TGLA) |
Affected |
3 |
3 |
1715 sq
m (615 sq
m of Lot No. STT3706K&T STT and 1100 sq m of Lot No. GLA-TKT 1726 TGLA) |
Affected |
2 |
3A |
1707 sq
m (612 sq
m of Lot No. STT3706K&T STT and 1095 sq m of Lot No. GLA-TKT 1726 TGLA) |
Affected |
1 |
*
Ranking: 1 = most preferable & 3 = least preferable under this viewpoint
(X) Environmental Impacts
In evaluating the recommended road
improvement option, the comparison of major environmental impacts (noise and
air quality) generated from the road against all options is mainly
focused. The anticipated differences
among the options are listed as factor for comparison:
(i)
Noise Impact
Noise impacts
during construction and operation phases are taken into consideration.
(ii) Air Quality Impact
The different physical alignments would
impose different separation distance among sources and receivers and hence lead
to variation on pollutant dispersion.
Therefore, comparison of air quality impact during construction and
operation phases is to be made through the consideration of separation
distance.
(iii) Landscape and Visual Impacts
In view of the similar nature of works and
work areas between different options, no significant difference is anticipated
in comparison.
The factors taken into consideration in
comparison of the options are described in the below tables with the ranking determined
accordingly.
Table 2-10a Consideration on Environmental Impacts
Option |
Factor (i) –
Noise Impact |
Factor (ii) – Air Quality Impact |
2 |
(a)
Works area boundary is around 30m from
the closest NSR |
(a)
Air quality impact to be mitigated on
site |
(b)
Noise from the proposed flyover is
mitigated. |
(b)
Around 30m separation distances from
additional traffic lane to Fung King House and around 60m to Lai King
Catholic Secondary School. |
|
2A |
(a)
Works area boundary is around 30m from
the closest NSR. Works area is larger
than Option 2. |
(a)
Air quality impact to be mitigated on
site |
(b)
Noise from the proposed flyover is
mitigated. |
(b)
Around 30m separation distances from
additional traffic lane to Fung King House and around 60m to Lai King
Catholic Secondary School. |
|
3 |
(a)
Partial noise enclosure construction
anticipated over existing roads.
Considerable amount of night time construction works anticipated and
in close proximity to Fung king House.
Significant construction noise impact is anticipated. |
(a)
Air quality impact to be mitigated on
site |
(b)
Noise from the proposed flyover and
section of KCR is mitigated. |
(b)
Shortest separation distance among all
options. |
|
3A |
(a)
Partial noise enclosure construction
anticipated over existing roads.
Considerable amount of night time construction works anticipated and
in close proximity to Fung king House.
Significant construction noise impact is anticipated. |
(a)
Air quality impact to be mitigated on
site |
(b)
Noise from the proposed flyover and
section of KCR is mitigated. |
(b)
Shortest separation distance among all
options. |
Table 2-10b Rankings of Factors of
Environmental Impacts
Option |
*Sub-ranking of Factor (i)(a) |
*Sub-ranking of
Factor (i)(b) |
**Sub-ranking of
Factor (ii)(a) |
*Sub-ranking of
Factor (ii)(b) |
**Sub-ranking of
Factor (iii) |
*Overall Ranking |
2 |
1 |
2 |
- |
1 |
- |
1 |
2A |
2 |
2 |
- |
1 |
- |
2 |
3 |
3 |
1 |
- |
2 |
- |
3 |
3A |
3 |
1 |
- |
2 |
- |
3 |
*
Ranking: 1 = most desirable and 3 = least desirable
** No significant difference
(XI) Capital and Recurrent Cost
The annual recurrent expenditure arising from
the proposed structures is taken into account in evaluation of options. The
proposed items induced the most capital and recurrent costs are mainly the
highway structures, which are:
(i)
The
extent of the bridge works. For
comparison purpose, the surface area of bridge deck [Adeck]
was estimated for each option.
(ii)
The
extent of the noise mitigation measures. For comparison purpose, the surface
area of noise mitigation measures [Anmm] was
estimated for each option.
(iii)
The
extent of other major items of works. With
the proposed options, the major items of works include:
- Footbridge NF303. For comparison purpose, the surface area of
proposed reconstructed footbridge [Afootbridge] was
estimated for each option.
- Subway NS10A.
For comparison purpose, the surface area of proposed extension to subway
[Asubway] was estimated for each option.
The factors taken into consideration in comparison of the options are
described in the below table with the ranking determined accordingly:
Table 2-11 Consideration on Capital and Recurrent Cost
Option |
Factor
(i) [Adeck] |
Factor
(ii) [Anmm] |
Factor
(iii) |
*Ranking |
2 |
2630 sq m |
3455 sq m |
(a) Afootbridge =
440 sq m (b) Asubway =
Nil |
1 |
2A |
3919 sq m |
5402 sq m |
(a) Afootbridge =
440 sq m (b) Asubway =
Nil |
2 |
3 |
2340 sq m |
8615 sq m |
(a) Afootbridge =
440 sq m (b) Asubway =
15 sq m |
4 |
3A |
2066 sq m |
7940 sq m |
(a) Afootbridge =
440 sq m (b) Asubway =
9 sq m |
3 |
* Ranking: 1 = most preferable & 4 = least
preferable under this viewpoint
(XII) Maintenance Consideration
Maintenance is one of the considerations of
evaluation and assessment on an alignment scheme. It can be evaluated by analyzing the maintainability of the proposed items
(serviceability and reparability), future maintenance cost and time. The
comparison is focused on the maintenance consideration of special features of
the bridges which controls the maintenance cost and require particular
inspections, and the provision of clearance for maintenance (i.e. min. 2m
between existing and proposed structures).
(i)
Stitched
joint requires special attention on maintenance. For comparison purpose, the length of
stitched joint [Lstitch] was estimated for each
option.
(ii)
Provision
of min. clearance between existing and proposed structures.
The factors taken into consideration in comparison of the options are
described in the table below with the ranking determined accordingly:
Table 2-12 Consideration on Maintenance Consideration
Option |
Factor
(i)[Lstitch] |
Factor
(ii) |
*Ranking |
2 |
190 m |
>2 m |
1 |
2A |
190 m |
>2 m |
1 |
3 |
500 m |
<2 m |
3 |
3A |
486 m |
<2 m |
2 |
* Ranking: 1 = most preferable & 2 =
least preferable under this viewpoint
(XIII) Time for Completion
The estimation of the construction time depends on many factors such as
the nature of proposed structures, construction methods, site constraints, etc.
For evaluation and assessment of the optimal scheme, the following critical
factors are considered. Other constructions such as the utility diversion,
re-provision of footbridge and extension of subway will likely be carried out
in parallel with the major works. Hence, the influence to the construction
programme is considered as minor.
(i)
The
extent of the bridge works. For
comparison purpose, the surface area of bridge deck [Adeck]
was estimated for each option.
(ii)
The
extent of the noise mitigation measures. For comparison purpose, the surface
area of noise mitigation measures [Anmm] was estimated
for each option.
(iii)
The
complexity of the construction. With the
proposed options, construction will be
more complex for option(s) involving:
- Reconstruction of TK H/W pier(s). For comparison purpose, the number of pier to
be reconstructed was counted.
- Bridge deck(s) that requires stitch-jointing
to existing upramp. For comparison
purpose, the length of stitch joint [Lstitch] was
estimated.
- Construction of noise mitigation measures
adjacent to / over operational roadways.
For noise mitigation measures to be installed on newly proposed
bridge(s), the complexity of construction is considered to be lower.
The factors taken into consideration in comparison of the options are
described in the below table with the ranking determined accordingly:
Table 2-13 Consideration on Time for Completion
Option |
Factor
(i) [Adeck] |
Factor
(ii) [Anmm] |
Factor
(iii) |
*Ranking |
2 |
2630 sq m |
3455 sq m |
(a) Nil (b) 190m (c) Some
length beyond Gird F8 |
1 |
2A |
3919 sq m |
5402 sq m |
(a) Nil (b) 190m (c) Considerable
length beyond Gird H8 |
2 |
3 |
2340 sq m |
8615 sq m |
(a) Nil (b) 500m (c) Very
long length between J1 & K4 |
4 |
3A |
2066 sq m |
7940 sq m |
(a) Nil (b) 486m (c) Very
long length between L1 & M4 |
3 |
* Ranking: 1 = most preferable & 4 =
least preferable under this viewpoint
· Traffic & Other Operational Consideration – Both the “Permanent Traffic
Arrangement” and the “Alignment Design Standard” factors critically affect the
final performance of the improvement. The “Traffic Impact at Construction Stage” is
important in that the already congested TWR should not be critically affected
during construction. To summarize, this
viewpoint is the determining factor and is therefore assigned a more than pass
mark percentage of 55%.
· Engineering Consideration – This viewpoint compares the pros and cons on the engineering scheme
of the road improvement options and is assigned a percentage of 25%.
· Other Consideration – The factors under this viewpoint generally compare the road
improvement options in a boarder sense.
This viewpoint is assigned a percentage of 20%.
Table 2-14 Overall
Marking and Overall Ranking for Identified Options
Viewpoints |
Weighting |
Options |
||||||||||
Base |
Sensitivity Tests |
1 |
1A |
2 |
2A |
2B |
3 |
3A |
||||
A |
B |
C |
D* |
|||||||||
Traffic
& Other Operational Consideration |
55% |
50% |
60% |
50% |
50% |
Failed screening-weaving analysis |
Failed screening-weaving analysis |
|
|
Failed screening-road vert. clearance check |
|
|
i. Permanent Traffic Arrangement |
20% |
20% |
20% |
20% |
20% |
1 |
1 |
1 |
2 |
|||
ii.
Alignment Design Standard |
25% |
20% |
30% |
20% |
20% |
3 |
1 |
2 |
1 |
|||
iii. Traffic Impact at Construction Stage |
5% |
5% |
8% |
5% |
5% |
1 |
2 |
3 |
3 |
|||
iv. Other Operational Consideration |
5% |
5% |
2% |
5% |
5% |
2 |
2 |
2 |
1 |
|||
Engineering
Consideration |
25% |
30% |
20% |
27% |
25% |
|
|
|
|
|||
v. Bridge Scheme |
8% |
10% |
7% |
9% |
8% |
1 |
2 |
3 |
3 |
|||
vi.
Noise Mitigation Measure |
8% |
10% |
7% |
9% |
8% |
1 |
2 |
3 |
3 |
|||
vii. Utilities and Drainage Impact |
5% |
5% |
3% |
5% |
5% |
1 |
1 |
2 |
2 |
|||
viii. Impact on Other Elements |
4% |
5% |
3% |
4% |
4% |
1 |
1 |
3 |
2 |
|||
Other
Considerations |
20% |
20% |
20% |
23% |
25% |
|
|
|
|
|||
ix. Land Requirements |
3% |
4% |
4% |
3% |
3% |
3 |
3 |
2 |
1 |
|||
x. Environmental Impacts |
5% |
4% |
4% |
8% |
10% |
1 |
2 |
3 |
3 |
|||
xi. Capital and Recurrent Cost |
5% |
4% |
4% |
5% |
5% |
1 |
2 |
4 |
3 |
|||
xii. Maintenance Consideration |
5% |
4% |
4% |
5% |
5% |
1 |
1 |
3 |
2 |
|||
xiii. Time for Completion |
2% |
4% |
4% |
2% |
2% |
1 |
2 |
4 |
3 |
|||
Overall Mark - Base
Weighting: |
|
|
1.61 |
1.44 |
|
2.29 |
2.00 |
|||||
Overall Mark – Sensitivity Test A: |
1.53 |
1.50 |
2.34 |
2.08 |
||||||||
Overall Mark – Sensitivity Test B: |
1.70 |
1.44 |
2.29 |
1.98 |
||||||||
Overall Mark – Sensitivity Test C: |
1.51 |
1.49 |
2.34 |
2.10 |
||||||||
Overall Mark – Sensitivity Test D: |
1.51 |
1.49 |
2.34 |
2.10 |
||||||||
Overall Ranking : |
2 |
1 |
4 |
3 |
Remarks: Low score & rank 1= most preferable;
High
score & rank 4= least preferable
*
Hypothetic sensitivity test for Environmental Impacts
Table 2-15 Major Concurrent Projects
Project |
Planned
Construction Period |
Tsuen Wan Bypass, Widening of Tsuen Wan Road between
Tsuen Tsing Interchange and Kwai Tsing Interchange, and associated Junction
Improvement Works: and Retrofitting of Noise Barriers on Tsuen Wan Road |
The
implementation of Tsuen Wan Bypass is uncertain at this stage. |
Widening of Yeung Uk Road
between Tai Ho Road and Ma Tau Pa Road, Tsuen Wan |
No
physical interface |
Replacement and Rehabilitation of Water Mains
Stage 4, Mains in New Territories |
The
works are within the site boundary but the construction is Feb 2012-Nov 2015
which is before our tentative construction programme. |
Extension of Footbridge Network in Tsuen Wan |
No
physical interface |
Cycle Track between Tsuen Wan and Tuen Mun |
No
physical interface |
Reconstruction and Improvement of Tuen Mun Road |
No physical
interface |
Planned Landslip Prevention and mitigation works
for a man-made slop (feature no. 11NW-A/C516) located at Lai King Hill Road
near Ha Kwai Chung Polyclinic |
Works
will be carried out within the period from January 2013 to December 2014 that
before our tentative construction programme. |