27.10.2017, 16:46 Uhr

Ideas competition for the Mainflingen Bridge across River Main

The motorway directorate Nordbayern organized a competition for the replacement of the Mainflingen Bridge across the Main and chose LAP’s design of a girth construction as preferred option.

In total, 4 different approaches of a replacement bridge were submitted: a deck bridge, a cable-stayed bridge, an arch bridge and the girth construction. The last one not only convinced because of its aesthetics, but also due to lots of advantages regarding static and construction.

Between the towns of Mainflingen and Kleinostheim, the federal Highway A 45 crosses the Main and its protected landscape area and also the regional border of the two federal states of Bavaria and Hessen. Inspired by the hills located in the foreshore of the Main, LAP opted for a girth construction in order to catch the driver’s attention for the structure’s uniqueness and outstanding location on the one hand, and on the other hand, to have a structure which matches with its momentum lines perfectly into the nature’s surroundings.

The girth construction suits because of to its limited height, with is pylons beneath the tree line to the context of nature in the foreshore and convinces with a distinctive combination of nature and structure. For birds, flying alongside the river course, the bridge marks a significant crossing and distracts from the traffic.

The girth construction has a slim span of 135 m with two similar approaches. By shifting the foundations if compared to the existing structure, we get a symmetric situation alongside the Main. The bicycle path along the shore has now a clear view on the foreshore area. The transition of the structure to the deliberately kept plain approaches stays flawless with a constant construction height.

The slim composite steel construction consists of a flat grid with external longitudinal beams and cross beams, beneath the reinforced concrete deck. This leads to a low construction height under the deck, which maximizes the light-flooded area under the bridge. Compared with the low height of the existing structure, it is a significant enhancement. In the smooth transition, the structure is combined with the approaching area which has a constant height and is made of prestressed concrete. The compact substructures follow the same idea and adapt with minimal dimensions steadily into the nature.

The light coating of the structure reflects due to its fractured surface, all colors of the land and water; in the superstructure it reflects the colors of the sky.

Client:              Autobahndirektion Nordbayern
Architect:          gmp Architekten von Gerkan, Marg und Partner