Rio-Antirio bridge will be ready by 2004

Scenes like those witnessed during the recent Easter holidays – when thousands of drivers were forced to wait for hours at the ferry crossing between Rio and Antirio – will soon be a thing of the past when the bridge linking the two shores of the western end of the Gulf of Corinth is finally completed, by the end of 2004. The bridge, once the dream of the late statesman Harilaos Trikoupis, who hailed from nearby Mesolongi and whose name the bridge is to bear, is one of the few public works in Greece that has actually proceeded according to plan. Although the official completion date is still slated for December 24, 2004, many believe it could be finished a few months earlier, in time for the Olympic Games in the second half of August. The heads of the construction consortium, Gefyra SA, say the hard part is over. Since the summer of 1998 when the go-ahead was given to start work on the bridge, construction has been proceeding rapidly. Four years later, the foundations have been laid along with the four piers on which the bridge deck is to rest – work that represents 65 percent of the total. The unusual thing about this project is that the work is advancing under very difficult conditions. The sea in that part of the gulf is up to 65 meters deep in places, and the seabed subsoil on which the foundations have been laid is not strong. Then there is the frequent seismic activity in the area. Tectonic movements separate each side of the gulf by a few millimeters every year. The sea floor had to be reinforced with metallic inclusions in the form of hollow steel pipes, along with reinforced concrete pier bases each of which is 90 meters in diameter. The four pylons were built in three successive phases. The first phase saw the construction of the dry dock, a 22,000-square-meter, two-level «tub,» permitting the pier bases to be built two at a time. A «door» was then opened at the front of the dock, filling the space with 200,000 cubic meters of sea water so that the bases could be towed out to sea. This was first done in July 2000, when the first base weighing 70,000 tons was prepared. In the second phase the bases were transferred to the so-called wet dock, even though it is not surrounded by walls, but is simply the part of the sea near Antirio’s castle where the pylons are being constructed. The sea depth here is about 55 meters, and the pier being built is linked to land by a system of floating docks. The first such dock was towed there on October 5, 2000, where it was built up to a height of 66.5 meters. The final one was begun on January 23 this year and completed on April 22, when it was placed in position near the Rio coast. Once the piers are placed in their final positions – as all four now have been – the upper part is raised a few meters above the sea’s surface. For the remainder of the construction work, the pylon is surrounded by an island of floating platforms. The project has reached this stage and within the next few months a specially equipped ship is to arrive in Greece to transfer and raise the bridge deck, sections of which are to be built separately and hung from 368 stay cables spread out every 12 meters along the bridge in eight fan-shaped groups. Once completed, the Rio-Antirio bridge will be the largest cable-stayed bridge in the world: 40 kilometers (25 miles) of cables weighing a total of 5,000 tons, a 2,252-meter-long, fully suspended continuous deck (2,883 meters including the approach viaducts), moving as a pendulum during an earthquake. Its surface, 27.2 meters wide, will have two traffic lanes and one safety lane in each direction. Each pylon will be up to 227 meters high and weigh about 170,000 tons. The bridge has been designed to withstand earthquakes of a velocity in excess of one meter per second – likely just once every 2,000 years – the impact of a 180,000-ton tanker ship traveling at 16 knots, and winds of up to 265 km per hour.