The air-cushioned bridge

Materials World magazine
11 Jan 2018

A wildlife crossing over the future Koralm railway has been constructed using an air cushion underneath concrete.

Researchers from TU Wien, Austria, have developed a new cushioning method for the construction of a wildlife crossing across the Koralm railway, a high-speed line that will connect the Austrian cities of Graz and Klagenfurt.

Rather than using a support structure, engineers inserted an air cushion underneath the concrete, which was inflated during the construction process. The crossing is in the Carinthia section of the railway, which is being developed by Austrian Federal Railways.

‘It took around five hours to inflate the cushion and create an elongated concrete dome with an internal height of 7.60m,’ said Benjamin Kromoser, from the Institute of Structural Engineering at TU Wien.

Kromoser added that ‘the process requires a little more concrete but 40% less steel’, than more traditional methods. TU Wein also believes that the cushion is cheaper and more energy-efficient, reducing equivalent CO2 emissions by 40%.

‘The costs are expected to fall even further once construction firms have gained more experience of using the new technique,’ said Kromoser. ‘We estimate that it could ultimately reduce costs by 15–30%.’

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