Bridges, Road Bridges

Renewal of BW404a in the course of the A9 over the Main-Danube Canal


The existing three-span prestressed concrete structure 404a on the A9 motorway is located near Hilpoltstein, south of Nuremberg, and is to be replaced by a new structure.
For the new replacement structure, the innovative technology of the carbon network arch will be extended to road bridges for the first time. Two single-span substructures (one for each directional carriageway) were designed for this purpose, spanning the Main-Danube Canal and two riverside paths. The Federal Ministry of Digital and Transport, the Federal Highway Research Institute and Autobahn GmbH have therefore granted approval in individual cases (ZiE).
The special feature of the design are the tension members of the network arches, which are made of a fiber composite material with carbon fibers and a special loop connection.
The layout and design of the arches is determined by the extremely skewed intersection situation: The superstructures of each directional carriageway are supported by two free-standing, overhead network arches. As a result, two arch levels are located directly next to each other in the middle between the lanes. A parallel arrangement of the two adjacent arches creates a clearer view, calms the hanger network into graphically parallel elements and also creates continuous spaces between the hangers.

Bridges, Road Bridges
Hilpoltstein, Germany
Marx Krontal Partner – MKP GmbH; MPA Materialprüfanstalt Universität Stuttgart; EMPA Eidgenössische Materialprüfungs- und Forschungsanstalt, Dübendorf, Schweiz
Die Autobahn GmbH des Bundes
Project Responsibility
Knut Stockhusen


Technical Data

Main span
105.40 m
2 x 18.85 m (between railings)
Superstructure height
14.5 m
2 x 3 + hard shoulder
Carbon hangers with loop connection
Bridge area
1,987 m² per substructure
Skew angle
140.6 gon




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