A new modular mobile overpass design allows vehicles to travel directly over sections of highway that need repairs, rather than taking a detour.
Workers installing the ASTRA mobile overpass. (Video: Swiss Federal Roads Office)
Named the ASTRA Bridge, this design aims to make travel easier for drivers and safer for road workers. The project was created by the Swiss Federal Roads Office, as reported by New Atlas on May 24. The original version of the ASTRA Bridge was tested on the A1 motorway in Switzerland in 2022, followed by trials of an improved version. The second version was installed on the A1 in April 2025 and will remain in place until August.
Shortly after roadwork was scheduled, the affected highway section was closed over the weekend. At night, trucks delivered various segments of the ASTRA to the site, where workers assembled them to form an overpass extending the length of the repair zone. Ramps at both ends of the overpass allow vehicles to pass over the section. The following week, the ASTRA opened for drivers. Although they must reduce their speed to 60 km/h while crossing the overpass, they do not need to squeeze into a single lane or stop and wait for their turn to cross.
Simultaneously, road workers began dismantling and replacing the pavement underneath the overpass. They do not have to worry about being struck by passing vehicles, and they can work without concern for rain or sun. Additionally, since the repairs do not obstruct the busy traffic flow during the day, they can work during the day instead of at night.
Astra mobile overpass.
Due to insufficient space beneath the overpass for tall construction vehicles like concrete mixers to operate, workers utilize a transport lane running along the project. Depending on circumstances, that lane may be a pre-existing traffic lane on the road. Once the repairs on the initial highway section are completed, the entire overpass is raised 10 cm hydraulically, and then it is removed from the highway on motorized wheels to be transferred to the next segment. This process can be repeated multiple times until the entire project is completed.
Currently, the ASTRA Bridge measures 257 meters long, 7.57 meters wide, and 4.65 meters high. The working area beneath the bridge is 100 meters long, 5.1 meters wide, and 3.1 meters high. The installation and dismantling process requires 16 low-bed trailers making a total of 45 trips to transport all structural components in and out of the site. Additionally, the process also requires three cranes and two assembly teams of 14 people.
