A26 tunnel, Austria The A26 project stands out on account of its five different tunnel cross-sections. Photo: Peri

On the A26 tunnelling project in Linz, Austria, the first fully hydraulic tunnel formwork carriage with a caterpillar drive in Austria was used.

The project aims to ease congestion on the country’s urban transport network. Tunnel construction work to the north and south of the Danube for the access and exit routes for the new Danube bridge has been in progress since May 2020.

A large section of the tunnel runs underground so that the noise and pollution in the urban area are reduced to an even greater extent.

Five different tunnel cross-sections, profile transitions, tight radii of between 50m and 750m in the bends, and varying gradients: these were just some of the challenges that had to be overcome when constructing the 1,600-m-long access tunnels for the new suspension bridge.

To help with the project Peri engineers developed Austria’s first customised and fully hydraulic special-purpose steel formwork carriage with caterpillar drive and a weight of 250t. This alone was enough to produce the different cross-sections in a total of 170 concreting sections.

Given the fact that the very tight curve radii made it difficult to transport the tunnel carriage, an innovative caterpillar system was used. Photo: Peri

Given the fact that the very tight curve radii made it difficult to transport the formwork carriage, an innovative caterpillar system was used to move it.

In addition, the formwork carriage had dimensions of 8.07m in height and 14.50m in length as well as 10.70m in width when ready to move and 11.20m in width when ready to pour concrete.

Peri assembled the formwork carriage in front of the tunnel entrance and, a short time later, the first concreting section was successfully completed, meaning that the formwork could be stripped the very next day and the formwork carriage moved forward to the next concreting section in an efficient and time-saving manner.

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