Tri-Countries Bridge, Weil am Rhein, Germany, and Huningue, France

Tri-Countries Bridge between Weil am Rhein, Germany, and Huningue, France, has been awarded the 2009 IABSE Outstanding Structure Award. The Outstanding Structure Award Committee was chaired by Mr Loring A. Wyllie Jr., USA.

In the border triangle of southwest Germany, this new pedestrian bridge across the Rhine River near Basel was opened in March 2007. The bridge near the border to Switzerland majorly improves the infrastructure in the region and connects Germany and France.

This asymmetric arch bridge without any piers in the water represents an innovation for a footbridge across the Rhine River. The steel arch bridge has a total length of 248.00 m and a main span of 229.40 m, the world´s largest for pedestrian bridges. Ramps and stairs allow access to the main bridge from both sides. For handicapped people a lift is built on Huningue side, thus further improving the efficient

use for the community. The very slender arch bridge has the best fitness for purpose to meet the functional and aesthetical requirements, resulting in a very elegant appearance.

The northern vertical tubes have two hexagonal steel box cross sections, the southern circular hollow section is inclined. The complex details are carefully designed with regard to durability and aesthetics. To avoid gusset plates the joints of the arches are built with cast steel nodes. This support arrangement is fixed for longitudinal displacement, but restrains horizontal rotations. The quality of design and construction of the complex details is shown e.g. in the base of the arch on the western bank, for which the latest research and development results for cast steel nodes were utilized.

The inclined locked coil rope hangers connecting the orthotropic deck with the arch, use open sockets to permit the adjustment of the cable lengths. In order to make efficient use of materials and to save energy, the amount of structural steel was minimized to 1020 tons. The construction with a single asymmetric arch was only possible by using steel. The shape of the bridge is simple but expressive and follows strictly the optimal flow of forces.

The Award Presentation will take place on September 9, 2009, at the Opening Ceremony of the 33rd IABSE Symposium in Bangkok, Thailand.