THE 5TH CROSSING AT DUBAI CREEKEdit profile
INTRODUCTION Aedas design for the 5th Creek Crossing combines architectural beauty, engineering ingenuity and a unique approach to environmental sustainability to create a modern day landmark. This design addresses Sheikh Mohammed’s concern to create a truly sustainable and environmentally conscious city in Dubai. Never before has a bridge design integrated the land it connects and the water it crosses to create a new wildlife habitat, urban oasis and green lung at the heart of a world class metropolis. The idea is simple, by limiting the navigation channel to the minimum required for today’s and future maritime traffic the remainder of the huge width of the Creek may be planted out with floating reed beds interspersed with pontoon decks. These reed beds will provide a habitat for wildlife and birds. Channels through the reeds will provide facilities for boating and canoeing as do the main rivers of Europe and America. Floating pontoons within the reeds will provide facilities for the public to view the wildlife and for restaurants and entertainment facilities. The bridge itself and the banks of the Creek will provide access to the floating reed beds and pontoons. The Bridge Design The bridge comprises twelve carriageways and two walkways which measure an overall width of over 75 metres. Our primary concern is to break this width to allow sunlight and air through the bridge structure to the river below. In order to do this, we have divided the North and South bound carriageways and the two flanking pedestrian ways into four separate bridge structures. The roadways are additionally separated vertically by increasing the upward gradient relative to the downward gradient. The East pedestrian walkway is maintained at a very high elevation whilst the West pedestrian walkway is maintained at a low elevation relative to the road crossing. This three dimensional sculpturing of the four crossings allows air and light to pass through the structure to the river and its activities. The pedestrian walkways on each side are connected to the reed beds and floating pontoons below and so the entire bridge becomes not just an urban connector between two landforms but also an integrated access to the newly created recreational facility and wildlife habitat below. Design Metaphor The design metaphor for the 5th Crossing is taken directly from the Arab marshlands of Iraq. The Mesopotamian Marshland provided a sustainable environment for many thousand of years. The floating reed beds of the marshland were used as platforms for housing and agriculture and the reeds were used to construct dwellings, boats and artifacts of all manner. Sustainability How can a bridge be sustainable? A bridge utilizes scarce resources of steel and concrete. The traffic generates pollution dust and fumes. To be sustainable, a bridge must add back to its environment. How can it do this? A bridge can only add back to its environment if it engages with that environment. Here at the 5th Crossing, we have a vibrant water side community, we have tourists and we have a nearby residential community. To the North of the river, we have the old town to the South, the new town. The Creek itself is a salt water creek. The climate is hot for most of the year and dry. The city is dusty and surrounded by sand. To be sustainable we must bring all of these ingredients together into a single undeniable solution. The bridge must create shade but not a prohibitive dark 70 metre wide tunnel. The bridge and the riverbanks may provide access in addition to merely crossing from side to side. The salt water of the Creek may provide cooling and the wildlife habitat and a base for plant growth in addition to a navigable channel. The two meter tidal reach can provide power, not just for the bridge itself but also for waterfront lighting, restaurant and retail outlets associated with waterfront activities. The support structure of the bridge is envisaged as a series of 1.2m pylons. These pylons or struts emerge from the riverbed. They are constructed at slight angles to improve the rigidity of the bridge structure in a very simple and direct way without the need for large concrete piers. The multiple support struts are easy to construct into the riverbed and the construction process has minimal impact upon the surrounding environment and the Creek itself. Reed Beds Construction GRC trays filled with 300mm of earth are floated 300mm below the water surface. These trays are anchored together and rise and fall with the two meter tide by rollers upon vertical piles. They are simply semi-submerged pontoons. The reeds are grown in patterns of islands allowing channels for canoes and kayaks to pass between. The channels are safe because the water is only 1 foot deep to the surface of the soil in the trays below. The Pontoons The pontoon decks are simply constructed timber pontoons floating within the reed beds. These linear pontoons are roughly 6m wide by 15 to 40m long. The pontoons provide a variety of functions. They provide restaurants and entertainment facilities. They also provide a point to moor canoes and to carry out maintenance and rental of these. They can provide children play areas. Some will be used for nature exploration and bird watching. Some may be used as a museum or exhibition resource. All of these different activities when taken together will provide a continuous source of activity generation on the banks of the river and on the river itself. The 5th Crossing will become a focal point not just for crossing the Creek but for the activity generated on the Creek. This is truly a sustainable solution, giving back to the environment from which it is situated.