Extradosed bridge
An extradosed bridge is a hybrid design that blends two kinds of bridges: the prestressed box-girder bridge and the cable-stayed bridge. The key idea is to use external tendons that rise upward from the deck to short towers. These tendons are not treated as traditional stay cables; instead they act as external post-tensioning that helps push and support the deck. The name comes from extrados, the upper curve of an arch, reflecting how the tendons curve upward from the deck.
Look and feel: extradosed bridges usually look like a cable-stayed bridge but with very short towers and shallower, flatter decks. The stays are at a shallow angle and create a fan of cables from the towers, often leaving an open window between the stays and the deck. This design gives a lower height profile while still providing a strong connection between the deck and the towers. Spans are typically in the mid-range, about 100 to 250 meters.
How they carry loads: the deck or girder in an extradosed bridge is relatively stiff, so it carries a large portion of the traffic load itself. The stay cables carry a smaller portion of the live load than in a tall cable-stayed bridge—usually between 20% and 60%. Because the cables experience smaller and less variable stresses, engineers can design them more efficiently. The tendons railing over the towers are usually continuous over saddles and anchored at the deck.
Why choose an extradosed bridge: they can save material and offer a good balance of height, clearance, and aesthetics for mid-length spans. They are often chosen when a tall cable-stayed bridge would be visually intrusive or when a long girder bridge would be impractical.
History and spread: the concept grew out of ideas developed in the 1980s. The Ganter Bridge in Switzerland and early Polish examples helped shape the idea, and Jacques Mathivat popularized the term extradosed and its design approach in the early 1980s. The first bridges built with this approach appeared in the 1990s, such as Ponte dos Socorridos in Portugal (1993) and the Odawara Blueway Bridge in Japan (1994). In North America, the North Arm Bridge in Vancouver (completed in 2008) is often cited as the first true extradosed bridge there.
Notable examples exist around the world, with Japan and Korea having many projects. The Rose Fitzgerald Kennedy Bridge in Ireland (opened in 2020) is one of the longest extradosed bridges in Europe. The Arrah–Chhapra Bridge in India (completed around 2021) is among the longest multi-span extradosed bridges. Other standout examples include bridges in Norway, Poland, and Canada, each illustrating the distinctive low-tower, fan-shaped cable arrangement that defines the extradosed style.
This page was last edited on 3 February 2026, at 08:50 (CET).