Particularidades regionales impuestas en el poncho

(1) The appearance of a bridge shall be considered for the daytime as well as the night time hours, with respect to pedestrian and vehicular traffic, and based on a pleasant appearance at a distance. It shall be noted that maintenance is an issue if additional lighting beyond what is required for trafficking is proposed, but for structures that are focal points and will become local or regional landmarks, it can be a desired option. (2) A well thought out lighting plan is important. The design will dictate the outlook of the

highway structure, especially during night time. Interior and exterior lighting require a coordinated plan where surrounding structures contribute to the overall night time streetscape rather than compete individually. Lighting shall first achieve the functional tasks and not be obtrusive to users and the general public. During day time, the lighting fixtures shall appear visually congruous with the surroundings.

(3) The following aspects shall be considered functionally: adequate lighting for the safety of traffic, and sometimes for navigation guidance of air traffic near tall bridges, and pleasant ornamental lighting especially with respect to slow moving traffic such as pedestrians and bicycles. Lighting can also be provided to cast certain elements of a bridge into shapes and textures such as barriers, piers and columns, abutments and

towers of larger bridges. Figure 15.29 illustrates how lighting add aesthetic value to a highway structure.

(4) For subway entrance, footbridge and walkway, efforts shall be made to provide a transparent or translucent roof cover. It will allow penetration of natural light, evoke a sense of openness and reduce lighting costs.

(5) With respect to the luminance level of functional lighting for highway structures, reference shall be made to the guidelines provided under HyD‟s Public Lighting Design Manual. During retrofitting, upgrading or major maintenance works to highway structures, due consideration shall be given to improving the standard of luminance levels in line with the recommendations under Public Lighting Design Manual, where appropriate, to facilitate the disabled and improve security to users.

15.6 EXTERNAL OR ANCILLARY FEATURES

15.6.1 Landscaping

(1) Landscape element is an integral part of the highway structure that needs to be considered in the initial stage of design process. A landscape section forming part of a design memorandum shall be developed in the project initiation stage, with specific landscape goals, assessment criteria to measure its effectiveness, and guidelines for landscape and surface treatments.

(2) Integration of the highway structure into its surrounding landscape is one of the most important consideration in aesthetic design. The creation of wastelands under overhead structures due to a lack of light, access preventative treatments or other inability to utilise these spaces has an adverse effect on the aesthetic quality of the structure and shall be minimised.

(3) Provision of soft landscape in form of “greening” is of increasing demand from the general public. Designers shall explore the opportunity for incorporating soft landscape and planting facilities onto structures and in its vicinity to enhance the visual and living quality of the whole environment. Regarding the provision of permanent planters and irrigation systems on future footbridges and flyovers, reference shall be made to Environment, Transport and Works Bureau Technical Circular (Works) No. 10/2005. (4) Soft landscaping, in particular tree and shrub planting, have the benefits to :

(a) anchor the structure on the ground plane; (b) soften the scale and extent of hard surfaces; (c) screen parts of structure;

(f) add visual interest to the landscape; and (g) stabilise earth slopes/surface.

(5) Soft landscape plays an important role, both to mitigate the visual impacts of the highway structure and to establish a distinctive character for the visual envelope. In general, the plant species selected shall possess a particular form, colour, and texture. Large mature trees shall be planted where practicable, to provide a dramatic vertical expression to set a backdrop for the visual environment and contrast the horizontal lines that typically dominate a structure. Planting shall be placed in a gradually layered manner to open up the roadway space. To create a more natural environment, repetition of planting monotony shall be minimised. The resulting profile shall undulate and vary somewhat in elevation along the highway structure.

(6) Creeper/vertical planting, shrubs and ground cover shall be adopted to reinforce the basic landscape theme, and to add colour and interest. On extended routes, combinations of shrubs may be used to develop identities along different sections of the route to assist recognition by the motorists and develop a sense of arrival to areas of significant prominence.

(7) An alternative way of increasing the level of perceived soft landscape is “borrowed landscape” which refers to the use of existing planting outside, but adjacent to the highway structure. This will suit situations where the actual available area for planting at the highway structure is severely limited or considered impractical for reasons of irrigation and maintenance access. An example of this would be to utilise existing tree planting behind a transparent noise barrier to soften the visual impact of the motorists. (8) An integrated landscape design enhances the visual appearance of structures

considerably and shields up the less attractive parts of the structure. In the aesthetic design of structures, the following aspects need to be addressed :

(a) provision and choice of soft and hard landscape on and around structures; (b) maintenance requirement;

(c) engineering consideration;

(d) visual continuity to local streetscape/townscape; and

(e) future development and flexibility for change in landscape design.

(9) Hard and soft landscaping including planting, decorative lighting, furniture, and architectural features at structures provide a more enjoyable experience for pedestrians and road users. In addition, soft landscaping provides an orientation that is frequently needed to visually navigate complex urban environments by enhancing roadway delineation, screening undesirable elements and separating incompatible land uses. They also aid in improving environmental conditions through buffering of dust, noise and reducing glare.

(10) Plant species with low demand of water supplement and reasonable resistance to pests and disease infestation shall be selected. Plant groups with similar levels of maintenance requirements shall be placed together. Requirements of irrigation systems and maintenance access shall be agreed with the maintenance authority.

(11) Placement of soft and hard landscape elements shall not obstruct the motorists‟ sight lines and visibility splays as recommended in the Transport Planning and Design Manual (TPDM) Volume 3, Section 3. The requirements under the TPDM Volume 6, Chapter 8 shall also be referred to with respect to the provision of suitable physical constraints, such as planters, to areas underneath highway structures where headroom is less than 2 m.

(12) Special consideration shall be given to landscape treatment under elevated roadways, to integrate these areas with adjacent pedestrian and/or planted areas and not to leave them as sterile and unpleasant environments. Landscape design shall integrate all the hard and soft landscapes into a perfect matrix that visual obstruction to other fixtures such as fire hydrants and traffic signage will not be caused. In particular, 1.5 m all-round clearance should be maintained at the fire hydrants and the surrounding ground shall be formed lower than the hydrant pit cover to ensure that any emergency operation and the like will not be hindered.

(13) A highway structure shall integrate harmoniously with its surrounding environment, townscape or streetscape to achieve a visual continuity. This is particularly important for grade separated pedestrian facilities within urban environments, since the size and scale of the structure will often allow the structure to fit wholly within the visual envelope and form a major visual marker within the local townscape or streetscape. Reference shall also be made to the Streetscape Master Plan of the respective District, if any, as well as checking for any streetscape enhancement works being planned in the vicinity of the highway structure, and which style/type of enhanced paving and street furniture are to be adopted in such works. A co-ordinated landscape design to tie in with the pre-set theme under the Streetscape Master Plan shall be developed in such a way that harmony within the entire visual envelop is not disrupted.

(14) Generally, the costs associated with hard and soft landscape works are usually a small percentage of the overall capital costs. Given the value of environmental contribution and visual effectiveness of these measures, landscaping is a cost effective way of improving the appearance of highway structures as well as providing a more pleasant environment for the public users.