Marc Mimram has beaten seven other teams to design a new €60m highway and tram bridge over the Danube in Linz, Austria. The other competitors included heavyweights such as Leonhardt Andra, Flint and Neill, Knight Architects, Dietmar Feichtinger and Dissing + Weitling.
It's a big bridge, some 30m and 400m long in total, and it's perhaps surprising to see a winner which is an essentially entirely new type of bridge. Essentially, it's a steel cantilever bridge along the lines of the Forth Railway Bridge, but with a number of unusual features.
The cantilever trusses are curved rather than comprised of straight pieces, requiring significant quantities of additional steel to resist the local bending induced in the steelwork. Very limited support is provided to the deck, which therefore has to be excessively deep.
The oddest feature, however, is the fact that the cantilevers sit on single lines of bearings, so that under uneven loading, the only stability is provided by the connection between adjacent cantilevers. Those short connection pieces don't really look stiff enough to provide that stability, and I wonder quite how the engineer has persuaded the design to work.
Of the other designs, the 4th prize entry is the most ambitious, with what appears to be a 250m span network arch bridge (just shy of the existing longest span of this type), a very challenging and complex structure to build.
Winner - Marc Mimram
2nd Prize - Öhlinger+Partner ZT GesmbH, Ponting Consulting Engineers and Zeininger Architects
3rd Prize - Gruppe VCE Vienna Consulting Engineers ZT GmbH, FCP Fritsch, Chiari&Partner ZT GmbH and Quist Wintermans Architects
4th Prize - SSF Ingenieure AG, ISP ZT GmbH and Knights Architects