In Switzerland, a new attempt will be made on April 7th to provide a motorway construction site with a so-called Astra Bridge. This means that a lane does not have to be closed; cars can drive over it while construction is taking place underneath. It was used for the first time in the summer of 2022 to renovate the A1 motorway between Luterbach and Recherswil; the attempt was stopped prematurely because long traffic jams arose at the motorway bridge. After these initial experiences, the Astra Bridge was revised according to the Swiss Federal Roads Office; it is now to be placed again between Luterbach and Recherswil and will remain there until around mid-August.
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The Astra Bridge has a modular structure and offers 5.10 m wide and 3.10 m high space for working. When put together, the bridge parts and ramps result in a length of around 260 meters. The segments are equipped with a chassis and can be lifted hydraulically, so the bridge can be moved to the next construction site section remotely. According to SRF, the development and construction of the bridge cost around 20 million francs (20.5 million euros), and the optimization cost another 5 million.
Shallower ramp angle
During the first use of the Astra Bridge, it became clear that the entrance and exit ramps should be made flatter, writes Astra. The revised bridge has been extended by around ten meters on both sides. “This results in a flatter ramp angle, which massively reduces the impact that occurred during initial use,” says a statement. In the NZZ am Sonntag it is described like this: “Truck drivers complained about the steep driveway. They were almost thrown out of their seats.”
According to Astra, driving tests with semi-trailers or vehicle transporters have now shown that the bridge can be driven on at a speed of 60 km/h without any concerns and without restrictions. Higher speeds are also possible for police and medical vehicles. The slope of the ramps is 1.25 to 6 percent. One of the invited test drivers complained about the Astra pilot project, reports the NZZ am Sonntag. According to him, the optimized bridge is a little better. In principle, however, every driver will slow down if “such a monster” is on the highway.
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The Astra wants to accompany the renewed use of its bridge together with the Solothurn canton police “with comprehensive monitoring and accompanying measures”. Traffic jams beyond the known extent and alternative traffic on cantonal and municipal roads should be prevented. This is ensured by alternating text displays that provide information about travel times on the motorway, cantonal and municipal roads. If necessary, exits should also be designated. “Despite all efforts to ensure traffic flows as smoothly as possible, a construction site remains a construction site,” writes Astra. There is no guarantee that traffic will flow unhindered.
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