PLATFORM OVERBRIDGES FOR THE CHANNEL TUNNEL FOLKESTONE TERMINAL

Abstract

This brief article describes the design of the 4 platform overbridges which will link shuttle train platforms with the rest of the Channel Tunnel Folkestone terminal. These are each about 300 m long and up to 5 lanes wide, with a total of 29 ramps, connecting them to platforms. The scale and geometrical complexity of the bridges is notable. They involve over 50 highly skewed spans over rail tracks, with a total deck area of 48000 square m. The construction programme time was very short. Simple and rapid construction methods were essential, and therefore steel or precast concrete was used whenever possible. The structure had to be robust against possible impact from derailed trains, and so wall supports were preferred. The bridges were founded on imported granular fill, placed over weathered to stiff clays. The structural system consisted of reinforced concrete boxes located between the rail tracks, with simply supported decks connecting them and spanning over the tracks. The simply supported spans consist of precast pretensioned concrete beams with insitu concrete decks. The lower sections of the ramps consist of earth fill between concrete retaining walls. The decks for the upper ramp sections are formed from precast concrete units which span transversely across insitu concrete walls. The precast concrete ramp deck units with their integral parapets are borne on thin rubber pads, on the supporting walls and are connected to each other structurally using insitu concrete. This design allows simple, repetitive and rapid construction methods to be used. The French title of this article is: Ponts sur les quais de la gare terminus du Tunnel sous la Manche, Folkestone. The German title of this article is: Gleisueberfuehrungen an der Endstation des Aermelkanaltunnels, Folkestone. For the covering abstract of the conference see IRRD 851274.