The future of motorway maintenance

ASTRA bridge

The world's first mobile construction bridge is making it possible for roadworks to be carried out on Swiss motorways while traffic continues to flow – above the heads of the construction workers below.

Peak hour traffic combined with much-needed motorway repairs means the same thing in virtually every metropolitan area in the world: traffic jams and angry drivers. At some point, however, the renovation and construction work can no longer be delayed, and the authorities have no choice but to close lanes. The economic damage is immense. According to the Swiss Federal Office for Spatial Development, in 2019 congestion on the Swiss road network alone led to a loss of almost 73 million vehicle hours  (compared to a free flow of traffic). This corresponds to an economic cost of around CHF 3 billion.

A mobile motorway bridge

To circumvent this problem, a world first has been built in Switzerland: a mobile motorway bridge that allows road users to drive parallel to the motorway at a speed of 60 km/h over the construction site. The 257-metre-long bridge, called the Astra Bridge, is completely mobile thanks to 22 vehicles connected by intermediate sections, and can be moved in stages to form a new section of motorway. The mobile bridge, and therefore the construction site, is moved forward by about 100 metres at night in order to renovate the next section. To move the bridge, the control software calculates a separate GPS route for each of the elements.

Improved working conditions

The benefits of such a system are manifold. The physical separation of traffic and maintenance work increases the safety of road users and the occupational safety of site personnel. Workers are also protected from traffic noise and the weather, and there is no need for stressful night work. As noisy work such as milling and paving can now be carried out during the day, there is virtually no construction noise at night. This reduces the burden on local residents.

Less night work

According to the Swiss Federal Roads Office (Astra), night work increases the cost of motorway maintenance by up to 15 percent. Every year, Switzerland spends CHF 750 million on maintaining 2,200 kilometres of national roads. Night work, which usually starts at 11pm and lasts until 5am at the latest, is very costly.

Second version with optimised access ramp

A first version of the Astra Bridge was already in use in 2022, but had to be optimised due to the excessive inclination of the access and exit ramps. The unique project is a world first and cost around CHF 26 million. The mobile motorway bridge is currently being used on the Recherswil-Luterbach section of the motorway towards Zurich.