Switzerland to revolutionise road maintenance with mobile bridges

2021/08/09 at 2:53 PM

Due to the growing traffic on the roads of Switzerland, the Federal Roads Office is looking for innovations to improve maintenance works. One of the possible solutions is a mobile bridge, which will be tested in autumn for the first time. How can it revolutionise road maintenance?

Hot July has marked an outbreak of the impressive road project for Switzerland as the country’s Federal Roads Office (ASTRA in German, FEDRO in English) started to assemble the first parts of the ASTRA Bridge, a mobile construction to be erected over the road during maintenance works. All the elements of the prototype will be put together on a construction site in Rothrist (within the Wiggertal junction) by late autumn. The innovation, which costs around 20 million Swiss francs (around 18.6 million euros), will be tested in the coming months. If the trials are successful, FEDRO will launch the pilot project by using the ASTRA Bridge. In spring 2022, the solution is expected to be applied when renovating the section of the A1 motorway between Recherswil and Kriegstetten.

Assembling the innovation

To assemble the ASTRA Bridge, the lane must be blocked or a single-lane oncoming traffic set up on the opposite lane. 16 trucks with low-bed semi-trailers are required to make 45 trips for moving eight ramp sections, 18 portals and 19 intermediate segments. The critical issue in assembling the solution or its dismantling is the use of the four pneumatic cranes, including two 110-tonne and two 45-tonne ones, that are required to put together all the components of the mobile bridge. Furthermore, four lifting platforms are used to screw portals and intermediate segments. Two montage teams of eleven personnel each are involved in the assembling process.

ASTRA Bridge for road maintenance, source: the Federal Roads Office (FEDRO)

The ASTRA Bridge is equipped with landing gear and intelligent control mechanism. As a result, it can be moved hydraulically lifted by 10 centimetres in the longitudinal and transverse directions. This makes it possible to carry out construction work under the structure over a length of 100 meters in a clearance profile of 5.20 meters wide and 3.10 meters high. If the works under the bridge are completed, it can be moved to a new construction site for a distance of up to 100 metres by using the remote control. Moreover, the intelligent control mechanism compensates for the uneven surfaces when moving.

Essential features

Having a length of 236 metres, a width of 7.3 metres, a height of 4.32 metres, a slope of the access and departure ramps at 6.1 per cent, the mobile bridges will allow the contractors not to stop the traffic during the maintenance or construction works. “The ASTRA Bridge not only ensures a high traffic capacity. Due to the spatial separation of the construction site and the roadway, it increases work safety for the construction workers,” the authority stated.

ASTRA Bridge in action, source: the Federal Roads Office (FEDRO)

According to FEDRO, road users can drive in two lanes at a speed of 60 kilometres per hour. The lanes, where the ASTRA Bridge is installed, will be regulated by temporary signalisation for a distance of around 1.5 kilometres. Since the innovation has an option for modular expansion, its length could be prolonged. This will result in larger construction sites being covered with mobile bridges. However, whether this option is useful or not, one can say only after the planned tests in Rothrist. As of today, FEDRO has estimated that the new solution could be applied to at least 13 per cent of motorways and main roads in Switzerland.

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