Saturday, April 19, 2008

Extreme airport runway - Madeira International Airport

Madeira International Airport is located 16 km from Funchal, the Capital of Madeira Island, in the city of Santa Cruz. Madeira Airport is the main gateway to the region and is used regularly by European airlines. Porto Santo Airport on the Island of Porto Santo is served from Funchal or Lisbon by the national airlines.

The length of the former runway of the Madeira Airport was a serious restraint to the development of the island, since only small and medium planes could land. Because of the local conditions, the solution adopted to extend its length to 2800 meters, was to slightly turn the existing runway and to build a bridge, crossing a shallow water bay nearby, 57 meters above the sea level. Madeira Airport is the largest construction project undertaken on the island. The new part of the runway is built partially over the sea and is impressively supported by 180 pillars.
This bridge, 1020 m long x 180 m wide, was designed to carry the loads of the landing impact of a heavy plane like Boeing 747. Due to the unusually large size of the structure, special care was taken in order to minimise the visual impact of the structural elements.
The structural solution, in reinforced concrete, consists of an array of large portal frames with circular columns (3 m diameter) and prestressed beams supporting a deck slab bi-directionally prestressed. When possible, direct foundations, through large concrete footings, were adopted. Where the rock formations at surface had no adequate capacity, indirect foundations with concrete piles (reaching depths up to 60 metres) were used.
The huge volume of earthwork generated a surplus quantity of this material, so the area of the bay beneath the structure was reclaimed, which very much facilitated the construction works. Special care was taken on making the embankment, in order to minimise the impacts on the local environmental conditions.

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