Switzerland: New mobile flyover bridge will allow roadworks without traffic interruptions

The Switzerland's Federal Roads Office has developed a new modular mobile flyover bridge named ASTRA. The prototype was tested on A1 motorway in 2022, but a new improved version was installed on this motorway last month and will remain there until August. It is mentioned that the current ASTRA Bridge is 257m long, 7.57m wide, and 4.65m high. The workspace underneath is 100m long, 5.1m wide, and 3.1m high.

This innovative bridge will allow vehicles to drive over sections of highway under construction, eliminating the need to detour. Therefore, it will be more convenient for drivers, and safer for road workers, while workers can work during the day, reducing the need for night shifts.

The process is simple, as, before the roadwork begins, the affected side of the highway is closed for one weekend. Then the ASTRA bridge sections are delivered at night and assembled to cover the work area, while ramps at both ends allow vehicles to drive on and off smoothly. Specifically, transporting and assembling the bridge requires 16 trucks making 45 trips, three cranes, and two teams of 14 people each.

Once the bridge opens to traffic, vehicles must slow down to 60km/h on the flyover, but they must avoid merging into a single lane or waiting for oncoming traffic to pass. Meanwhile, workers below can safely and efficiently repair the road, shielded from traffic and weather. In addition, a solution for tall construction vehicles that are unable to fit under the flyover is accommodated, as they can use a logistics lane beside the structure. This could be the road's passing lane or shoulder, depending on the situation.

Last, after completing work on one section, the flyover which is hydraulically lifted will be moved to the next section using motorized wheels and remote control. This process continues until the project is done.