In the coming years, the city will have to renovate central and important bridges for car and pedestrian traffic. The sometimes old age and the constant heavy load are increasingly causing problems for the buildings. The construction department’s list includes, among others, the Donnersbergerbrücke, the Hackerbrücke, the Wittelsbacherbrücke and the Thalkirchner Brücke at the zoo. This week, the city council decided on a construction program in two packages that includes 20 bridges and underpasses. There is no information yet about the time period and costs, as the years of planning are usually still in their early stages.
The Ludwigsbrücke shows how the general renovation of a central building can affect traffic in the city. The first work began there in 2019, which was delayed due to Corona and a lack of building materials. The route is completely closed for tram line 17, but a lane remains for cars and trucks that meanders past the construction site. A temporary bridge was built on both sides for pedestrians and cyclists. The Ludwigsbrücke is scheduled to be completed at the end of 2024, two years later than planned. The costs are said to amount to around 25 million euros.
Not every bridge in Munich will require as much effort to renovate as the Ludwigsbrücke, which stretches over the Isar Island and actually consists of two structures. But with central connections, the work involves a lot of effort and a long period of time. In addition, other projects such as local public transport must also be taken into account. Since many bridges and underpasses are now reaching an age in which massive damage can be observed, the construction department does not want to tackle project by project, but rather work through a list of priorities in an orderly program.
The basis is an examination of all 630 bridges and underpasses for pedestrians, cyclists and motorized traffic that fall under the city’s responsibility. The examiners awarded grades that were somewhat stricter than at school. A “Very Good” ranges from 1.0 to 1.4, and a “Good” rating from 1.5 to 2.0. Things get tricky with bridges starting with grade three. Then the condition is considered “insufficient”, from 3.5 it is said to be “insufficient”. These poor grades do not immediately mean that there is a risk of collapse, but they do indicate an acute need for action.
The need for maintenance and renovation has “increased exponentially”
Four pedestrian bridges failed the bridge test. In three of them the wooden supporting structure needs to be replaced. The most prominent case of renovation is the historic Mariannen Bridge, over which pedestrians come from Lehel to the Prater Island. A further 23 bridges received the second worst grade, but not all of them need to be addressed immediately. However, the construction program with 20 bridges includes the zoo bridge, whose renovation the SPD also hopes to improve local public transport. “A minibus over the Thalkirchner Bridge would finally connect the districts of Thalkirchen and Untergiesing-Harlaching. That would be a real improvement for the local people,” said city councilor Andreas Schuster.
So far this has not been possible because the lanes are too narrow, but construction officer Jeanne-Marie Ehbauer (Greens) gives hope in her draft resolution that this could change. The supporting structure allows for a widening of 5.6 meters, she writes. That’s enough for a minibus and probably even for dedicated cycle paths across the bridge.
The fact that bridges and underpasses are now the focus of engineers and structural engineers is due to their age and the ever-increasing load, especially from heavy traffic. The need for maintenance and renovation has recently “increased exponentially,” according to the construction department. The de-icing salt against ice and the pollution of the air with carbon dioxide also contribute to this. The most common types of damage include ruts, abrasion and cracks in road surfaces, leaky transition structures and rust in steel components.