3.              DESCRIPTION OF DESIGN MEASURES

3.1          Landscape and Visual Design Measures

 

During the detailed design stage, the proposed landscape and visual design measures in Section 14.3.3.2 of the approved EIA report and Section 14.2.4 of the EM&A Manual are considered.  They are proposed as far as practicable.  The following sections summarize the development of these design measures.

3.1.1      Aesthetic design on the viaducts

 

·        Optimizing the sizes and spacing of the bridge columns

In the design process, the sizes of the bridge columns have been minimized to reduce the bulkiness of the structure.  Spacing of the bridge columns has also adopted an evenly distributed spacing so that the structure would be aesthetically more pleasing as recommended by the ACABAS.  Please refer to Section 6.3.3 of the AIPSLW in Appendix A and Section 2.1 of the ACABAS Submission in Appendix B for more details.  The ACABAS submission has been reviewed and accepted by the ACABAS committee in July 2012. Further ACABAS submission was submitted on 2 January 2013 and was accepted with one minor comment regarding pier finishes.

·        Fine-tuning the location of the bridge columns to avoid visually-sensitive locations

As shown in Figures 14.1.3a to 14.1.3c of the approved EIA report, the visually sensitive receivers (VSRs) to the section of the HKLR under this Contract are mainly on the northern coast of Lantau Island where the existing view is an open view of the airport channel.  Adjusting the locations of the bridge columns will unlikely reduce the magnitude of landscape and visual impact to these VSRs by the construction of the HKLR.  As such, the JVs design aims at softening the structure with transparency and slenderness designs via carefully chosen column shapes, length and depth of deck. The aspect ratio of the column is driven by the structural requirements and optimized to give a slender but stable outlook. The span/depth ratio of the superstructure has been maximized in order to mitigate the weightiness look of the deck. Aesthetic design of the bridge form and its structural elements for HKLR is shown in the Photomontages in Figures 2 and 3 and Figure 13 in the ACABAS July 2012 Submission in Appendix B.

Figure 2. Photomontage of Proposed HKLR viewed from Sha Lo Wan

Figure 3. Photomontage of Proposed HKLR viewed from hiking trail near San Tau  

·        For HKLR, providing aesthetic design on the viaduct, at grade roads and reclamation (e.g. slim form for viaduct to minimize the bulkiness of the structure and to blend the viaduct better with the background environment, featured form of tunnel portals, roadside planting along at-grade roads and landscape berm on & planting along edge of reclamation area) to beautify the HKLR alignment

A slim form has been adopted to minimize bulkiness of the viaduct as discussed in Section 6.3.3 of the AIPSLW in Appendix A and Section 3.2 of the ACABAS July 2012 Submission in Appendix B.  Tunnel portal works are not within the scope of this Contract.  Roadside planting along at-grade roads will be discussed in the following Section.  Landscape berm on planting along edge of reclamation area is not applicable because the section of HKLR covered in this Contract does not involve reclamation works.

·        For HKLR, providing aesthetic design on the viaduct, tunnel portals, atgrade roads and reclamation (e.g. subtle colour tone and slim form for viaduct to minimize the bulkiness of the structure and to blend the viaduct better with the background environment, featured form of tunnel portals, roadside planting along at-grade roads and landscape berm on & planting along edge of reclamation area) to beautify the HKLR alignment

The selected soft and grayish natural colour of concrete for the viaducts has an unobtrusive tone which gives a sense of lightness and elegance that perfectly blend the proposed structure with the surroundings.

In addition, a slim form has been adopted to minimize the bulkiness of the viaduct as discussed in Section 6.3.3 of the AIPSLW in Appendix A and Section 3.2 of the ACABAS July 2012 Submission in Appendix B.  Roadside planting along at-grade roads will be discussed in the following Section.  Landscape berm on planting along edge of reclamation area is not applicable because the section of HKLR covered in this Contract does not involve reclamation works. 

 

·        Roadside planting and planting along the edge of the reclamation is proposed

Roadside planting is proposed along South Perimeter Road (SPR) and Chek Lap Kok South Road (CLKSR) adjacent to the proposed HKLR.  Detailed design of the at-grade planting is shown in Drawing nos. HKLR9/MMH/AIP/AI/LS00009 to HKLR9/MMH/AIP/AI/LS/00021 of the AIPSLW in Appendix A.  Design codes, considerations, approaches and details of the at-grade landscape design are discussed in Sections 2 to 6 of the AIPSLW in Appendix A. Planting along the edge of the reclamation is not applicable to this section of the HKLR as no reclamation works is involved.

·        Transplanting of mature trees in good health and amenity value where appropriate and reinstatement of areas disturbed during construction by compensatory hydro-seeding and planting

Transplantation is proposed for trees in good health with high amenity value and reasonably high post-transplantation survival rate.  Details of the transplantation proposal are discussed in Sections 2.8 and 6.2.2 of the AIPSLW in Appendix A.  Areas temporarily affected by the construction works, such as temporary road diversion and utility diversion, are proposed to be re-instated with tree planting, hydro-seeded grass and shrub/ groundcover planting as discussed in Section 6.2.3 of the AIPSLW in Appendix A.

Additional compensatory tree planting will be provided to meet the compensatory planting ratio of 1:1 in terms of both number and aggregated DBH.  Liaison with AAHK for additional tree planting area is on-going.

·        Protection measures for the trees to be retained during construction activities

Protection of existing vegetation is discussed in Section 2.7 of the AIPSLW in Appendix A.  Specification for tree protection is shown in Appendix B of the AIPSLW in Appendix A.

·        Maximizing new tree, shrub and other vegetation planting to compensate tree felled and vegetation removed

As discussed in Section 6.2.2 of the AIPSLW in Appendix A, compensatory tree planting has been maximized on site.  Additional off-site compensatory planting area will also be provided where feasible as required.

·        Providing planting area around peripheral of HKLR and HKBCF for tree planting screening effect

Tree planting is proposed on the north side of SPR and CLKSR as shown in Drawing nos. HKLR9/MMH/AIP/AI/LS/00009 to HKLR9/MMH/AIP/AI/LS/00021 of the AIPSLW in Appendix A.  These trees can act as buffer to the adjacent buildings and partially screen the hard structure of the proposed viaduct.  Planting on the south side of the proposed viaduct is considered infeasible as the bridge columns sit on the seawall.

3.1.2      Night-time lighting control

 

·        Aesthetic design of the bridge form and its structural elements for HKLR, e.g. parapet, soffit, columns, lightings and so on

Consideration will be given to decorative effects in the lighting design.  Subtle down lights will be employed on top of columns at the navigation channel to illuminate the emerged pile caps over water. This will serve the primary purpose as a warning to the marine traffic but at the same time create a nice visual effect on the viaducts at night. The illumination dissipates towards the base of the column giving the impression that the structure floats upon water and reduces the perceptible scale and bulkiness of the bridge. The proposed pilecap lighting is illustrated in Figure 4 in below.

 

Deck Section - Lighting_

 

Figure 4. Proposed road lighting and pilecap lighting

 

·        Considering the decorative urban design elements for HKLR, e.g. decorative road lightings

Lighting design has been carefully considered to avoid interference with aviation traffic. Normal street lightings are located in the central median so that they will not be in conflict with the Under Deck Inspection Vehicle. All road lighting on the viaduct will be controlled to prevent any glare or dazzle and all lighting will not be projecting skyward. A photomontage of the proposed light poles is shown in Figure 5 below.

 

Figure 5. Photomontage of Proposed Light Poles