Rio-Antirio bridge defies natural odds to bring Greece a step closer to modernity
Greece’s rugged and fragmented landscape has been a major impediment to the development of its transportation infrastructure since attaining nationhood in the 19th century. Prime Minister Harilaos Trikoupis in 1889 was the first to refer to the possibility of building a bridge to connect the southern Peloponnesian peninsula (16 percent of the country’s total area today but much more then) with the mainland, separated by the long and narrow Gulf of Corinth. His vision is now nearing fulfillment and the Olympic Flame is scheduled to inaugurate the crossing over the 2.8-kilometer (1.7-mile) strait on August 8, five days before the opening ceremony of the Olympic Games. The bridge is expected to be opened to traffic in early September, more than three months ahead of schedule. The Rio-Antirio bridge, to be named after Trikoupis, has a total length of 2,883 meters – with 2,256 meters of it representing the world’s longest cable-stayed suspended deck in five spans, the rest being two approach viaducts on either side. The three longest spans of the deck are 560 meters long each. The bridge will be an integral part of the Ionian Highway, a north-southwestern road axis planned to upgrade existing infrastructure with European Union subsidies and facilitate transportation between Greece and Italy through the northwestern port of Igoumenitsa. It is also located on the highway linking Patras, the country’s third-largest city and port 8km (5 miles) to the west, with Athens, 208km (129 miles) to the southeast. As well as reducing the journey time from northwestern Greece to the capital, the bridge is also expected to generate local traffic across the strait, particularly to and from Patras, as well as bolster development in the regions on the northern side, which are among the country’s poorest. The saving in time for motorists, who now cross the strait via ferry, is estimated at 40 minutes. The project is being implemented by Gefyra SA, a consortium led by French-based Vinci, a world leader in concession works, and includes five Greek companies, Hellenic Technodomiki-TEV, J&P-Avax, Athena, Proodeftiki and Pantechniki. Vinci holds a 53 percent interest in the consortium and the Greek partners the rest. The physical features of the strait presented considerable technical challenges to engineers. The combination of a water depth of up to 65 meters, the absence of solid seabed subsoil, high seismic activity and possible tectonic movements (the strait gains a few millimeters in width every year), made the project the most ambitious ever attempted in Greece. New engineering methods We developed totally new systems for soil reinforcement and insulating the deck from quake movements,» says Jean-Paul Teyssandier, president of Gefyra. The seabed under the four pylons, which reach a height of 164 meters above sea level, was reinforced with inclusions – hollow steel pipes 2 meters in diameter and 25-30 meters long – driven into the soil at a regular spacing. About 500 pipes were driven in at the four pier locations, each topped by a 3-meter-thick layer of gravel. The pylon foundations, or piers, rest on this reinforced seabed and are made up of concrete caissons 90 meters in diameter and 13 meters high, the largest ever constructed for a bridge. Each pier was constructed in dry dock, which was then flooded to make possible the floating of the pier and its towing to a deeper site called the wet dock. There, construction continued with the cone-shaped upper pier shaft to a height of 60 meters. The pier was then towed to its final position and immersed in the sea. The upper pier culminates in a 38-square meter platform embedding the four concrete legs of the pylon at deck level which then converge to the top head. The deck consists of prefabricated sections 12 meters long and 27.7 meters wide, each stabilized by two stay cables anchored at the head to provide a four-lane road, plus a 2-meter-wide pedestrian space on either side. The thickest cable is formed of 72 15-millimeter strands. The two central highest pylons rise 230 meters above the seabed, while a height of 57 meters from the surface of the sea to the suspended deck in the center of the bridge allows the passage of any sea vessel. The Rio-Antirio bridge can withstand the collision of a 180,000-ton tanker and wind speeds of up to 250 kilometers per hour, and can absorb displacement of up to 2 meters between any of its piers in the event of an earthquake. Damping devices connecting the deck to the top of each pier are designed to absorb any resulting pendulum movement of up to 3.5 meters. The pylons are hollow to improve earthquake resistance and are accessible at the bottom. Teyssandier says, unusually, no major problems were encountered during construction, thanks to good planning. «We had to provide for an ‘envelope’ of earthquake characteristics and the bridge can withstand the effect of 7 to 7.5 on the Richter scale without any difficulty,» reassures the Gefyra president. «It is certainly one of the safest places to be should there be a major earthquake.» After completion, the bridge will be operated and maintained by the Gefyra concession company for 35 years, and then transferred to public ownership. The total cost of the project, including financial expenses incurred during the seven-year construction period, amounts to 770 million euros. Of this amount, 335 million is a European Union subsidy and 362 million a loan obtained from the European Investment Bank (EIB), backed by commercial bank guarantees during the construction phase and repayable over 25 years. Gefyra expects crossing traffic, which has increased at an average annual rate of 5 percent over the last 30 years, to be in the order of 11,000 vehicles a day, up 10 percent from the present number carried by ferries. According to the concession contract, toll charges will be up to 10 euros for private cars and up to 45 euros for heavy trucks in the first year, to be inflation-indexed thereafter. The current respective charges by ferries are around 7.50 euros and 35 euros. They will continue to operate but the government has undertaken not to subsidize them. Gefyra plans to offer policies for frequent users, while pedestrians will cross free. Newsweek slips An article in the May 10 edition of Newsweek magazine, titled «A Bridge to Nowhere,» appeared as an overplayed attempt to portray the project as «testimony to Greece’s bungling efforts» to fulfill its aspirations for the future. The article suggests that the non-inclusion of a rail line in the project was a major mistake that condemns the «stubbornly underdeveloped» Peloponnese to remaining so. Notwithstanding the fact that the argument for a rail line in this case is not backed by any expert opinion or economic feasibility study, the Peloponnese is not «far poorer than comparatively wealthy northern Greece.» Indeed, as indicated above, the region northwest of the Gulf of Corinth, cut off from the more prosperous eastern mainland by the Pindos Mountain Range, is more likely to benefit economically from the improvement in transport communications due to the bridge. Epirus, where the port of Igoumenitsa is located, is one of Greece’s poorest regions.
