The ASTRA Bridge is a mobile construction site bridge that is designed for use during motorway maintenance work. Traffic can be re-routed over it while roadworks are carried out underneath. This allows works to be carried out during the day without closing any carriageways or diverting traffic. There is generally no need to close lanes or reduce lane widths or speed on the opposite carriageway, and the length of the roadworks site can be kept shorter.
The physical separation of traffic and maintenance work improves both the safety of motorists and the occupational safety of construction workers. Workers are also protected against traffic noise and bad weather, and they no longer need to carry out burdensome night work. As noisy work such as milling and road surfacing can now be done during the day, there is no construction noise at night, which eases the burden on residents.
The construction site bridge can also be used for other surfacing works, such as bridge repairs or the replacement of road expansion joints. Lorries with low-bed trailers and large cranes are required to assemble and dismantle the bridge.
Successfully optimised
The ASTRA Bridge was first used on the A1 between Recherswil and Luterbach (SO) in 2022. During this time, it was confirmed that the bridge works both conceptually and technically, and that roadworks under the bridge can be carried out as planned both in terms of schedule and quality. The autonomous moving of the bridge went smoothly, and vehicles were able to drive over the bridge without any accidents. Roadworks were carried out during the day, which meant less construction noise at night and more socially acceptable working hours for construction workers. Occupational safety was also improved as work could be carried out beneath the bridge, away from the traffic.
However, the flow of traffic during the pilot project was not as smooth as had been hoped for, which is why the ASTRA Bridge underwent some improvements during the past few months.
In close coordination with internal and external specialists, including the Swiss Federal Laboratories for Materials Science and Technology (EMPA) and various transport associations, measures were taken to improve the flow of traffic over the ASTRA Bridge. More specifically, the ramps were extended and the changes in gradient were improved. As a result, the initial gradient of the ramps was reduced from 6.1% to 1.25%. The improvements were successfully tested with various vehicles, including sports cars, caravan trailers, coaches, lorries and semi-trailers. All vehicles were able to drive over the ASTRA Bridge at 60 km/h without difficulty. The tests confirmed that the bridge is suitable for practical use.
Use
Against this background, the ASTRA Bridge is scheduled to be used once again on the A1 section between Recherswil and Luterbach on the carriageway towards Zurich in spring 2024. According to the current schedule, it will be assembled on the nights of 5/6 and 6/7 April 2024, and is expected to be in service until the end of August 2024. Until then, no work will be carried out on this motorway section.
