Grade 5 for A13 structure

Lueg Bridge on the Brenner Pass: checking how long it will last

Peter Augschöll (left) and Thomas Gabl from Asfinag are responsible for the bridge. However, the inspection is carried out externally.(Bild: Birbaumer Christof)

The 1.8-kilometre-long Lueg Bridge on the A13 Brenner freeway in Tyrol is still safe for traffic. However, a kind of "safety net" had to be installed under the weak points. Salt eats away at the structure. Experts are now carrying out an inspection to clarify what is still possible - and what is not - on the bridge, which is crucial for the route over the Brenner Pass.

"In the last inspection in 2021, it received a school grade of five." Asfinag bridge experts Peter Augschöll and Thomas Gabl look up at the Lueg Bridge. It can only be used with additional requirements, such as four so-called underpasses. In the (unlikely) scenario that something breaks at a connection between the five sections of the bridge, they would "catch" the roadway.

But civil engineer Augschöll is reassuring: the bridge is monitored too closely for this worst-case scenario. "If our sensors measure something, it would be closed. There is no danger for road users."

The truss-like supports would serve as a "safety net" in an emergency.(Bild: Birbaumer Christof)

According to Stefan Siegele, the Lueg Bridge in the rear Wipptal valley is the "best monitored bridge in Europe" - due to its condition.(Bild: Birbaumer Christof)

It is no coincidence that the Lueg Bridge is monitored so closely. The 1800 meter long structure is exhausted. When it opened 56 years ago, highway bridges were said to have a service life of 70 to 80 years.

Connecting sections as weak points: Salt damages them
The fact that the Lueg Bridge does not last this long is due to its construction and the weather. "You have to salt it because of the snow. And salt and steel don't mix well," explains engineer Gabl. On the Lueg Bridge, as described above, there are transitions between the five sections. "Salt water gets in there. But we can't get there for repairs," explain the bridge experts.

The salt is the main reason for the bridge's poor condition. "Of course, the heavy traffic also causes signs of fatigue. But we have that well under control."

If things continue like this, I don't think it will still be possible to drive over it in ten years' time.

Peter Augschöll, Asfinag

The other bridges along the A13 don't have a problem because of their different design. The Lueg Bridge, on the other hand, needs a main inspection every three years (normally six). This is currently underway again. Independent civil engineers are inspecting every centimeter of the structure from the inside and outside. The findings will be available in the summer and will then indicate what can still be done on the Luegbrücke.

Tapping tests are also part of the main inspection.(Bild: Birbaumer Christof)

It is expected that it will only be possible to drive on one lane from 2025. Asfinag Alpine Roads CEO Stefan Siegele does not believe that a total closure will be necessary. "We don't expect any major surprises."

And how long until nothing works at all? "If things go on like this, I don't think we'll be able to drive over it in ten years' time," Augschöll estimates.

New construction: two supporting structures, traffic can continue to flow
In the case of a new construction, a new support structure would first be built on the downhill side of the old bridge and traffic would then be diverted onto this. The old bridge would then be demolished and the second support structure for the opposite lane would be built there.

A number of decisions are still missing for the construction. The Ministry of Transport has given the green light, but as reported, the mayor of Gries lodged an appeal against this in the fall. So it will be some time before the Luegbrücke bridge can once again be awarded the grade "very good".