Dilapidated Bridges in Germany: Temporary Solutions Are Not Enough

Stuttgart / Nuremberg, Germany, February 25, 2025. The bridges in Germany are getting old, and many bridges are in urgent need of a major overhaul. This is an enormous challenge, and the funds for the essential refurbishment projects are scarce. The federal state of Baden-Wuerttemberg and cities such as Stuttgart and Nuremberg aim to tackle this marathon refurbishment work in a structured, cost-efficient and sustainable way. The expert teams of Drees & Sommer SE are supporting them in their scheduled long-term restoration and repair work. The consulting firm specializes in construction, real estate and infrastructure.

Crumbling concrete, rusting steel, declining load-bearing capacity – a worrying number of bridges in Germany are at risk. In the overall German motorway system there are currently more than 8,000 bridges which are deemed in need of refurbishment, and there are about 3,000 bridges which need to be overhauled on the other main trunk roads. These are the results of a study carried out by the German Federation for the Environment and Nature Conservation (BUND) on the basis of data provided by the German Federal Ministry for Digital and Transport (BMDV)[i]. A study published in 2023 by the German Institute of Urban Affairs (Difu) also found that half of the road bridges managed by local municipalities were dilapidated.[ii] In addition, there are more than 1,100 railway bridges in need of repair or replacement.[iii]

Senior expert Dr. Christian Ganz comments: “The numbers are one thing, but the symbolic impact of a collapsed structure such as the Carola Bridge in Dresden, or the closure of a major transport route for several years, is something else completely,” The civil engineer specializes in bridge construction at Drees & Sommer. He has supported projects such as the rebuilding of the Filstal Bridge, Germany's third highest railway bridge, and the construction of the new bridge over the eastern dock in Frankfurt am Main. “Seriously outdated and defective bridges, in particular, are not only a safety hazard – they also represent a drain on finances and personnel resources,“ Christian Ganz continues. 

The problems outlined by the bridge specialist can be clearly seen on the A45 motorway between Frankfurt am Main and Dortmund. The Rahmede Valley Bridge was completely closed in 2021 and finally demolished by detonation in 2023. Since then, traffic has been routed through the middle of the city of Lüdenscheid. The residents have to endure permanent congestion, increased fine particle pollution and constant noise. Logistics companies, craftspersons and service providers have to drive long detours, which costs time and increases energy consumption. As early as 2022, a study realized by IW Consult GmbH (a subsidiary of the German Economic Institute, IDW) for the public transport association Verkehrsverband Westfalen, calculated that the negative effects amounted to at least 1.8 billion euros^[iv] in the five years that had elapsed since the bridge was closed. Before the closure, about 48,000 cars and almost 16,000 trucks crossed the bridge every day. Since the closure of the Rahmede Valley Bridge, vehicle drivers have looked for alternative routes to the A45 motorway.

Many Bridges Are in the Second Half of their Lifecycle

To ensure that such negative effects are minimized as far as possible, Christian Ganz provides advice and support to cities, towns and villages, such as Stuttgart or Nuremberg, to help them with the strategic preservation management of their bridges, with a focus on their lifecycle. Most of the 28,000 motorway bridges in Germany were built between 1960 and 1980, and thus have their best days behind them: “In the lifecycle of bridges, a distinction is made between the first and second usage phase. Especially bridges built in the 1960s and 1970s are now in their second phase.” Bridges which were built with prestressed concrete in this period, in particular, are now in urgent need of refurbishment. That is not surprising. Heavy goods traffic has increased fourfold since then. Many bridges in the transport network were not designed for the loads which apply today, so structural stability is a major concern. The increasingly frequent extreme weather exacerbates the ageing processes.

Drees & Sommer’s senior expert explains: “The low maintenance needs and damage levels which are typical of the first phase of the lifecycle of these bridges have long passed. Now, it is becoming increasingly obvious that greater resources are necessary to preserve the structures.” Apart from the sheer number of affected bridges, he suggests that there are also a considerable number of specific challenges for structural engineering. For example, there is a lack of data about the condition of the individual structures. This also means that there is still inadequate digital information about key parameters. The universal staff shortages in public administration offices are also noticeable, and of course there is the question of the refurbishment work itself, which ideally needs to be carried out without closing the roads.

A Structured Timetable Instead of Patchwork

“Instead of the all-too-common patchwork approach, a structured timetable for the preservation of the bridges in Germany is necessary,“ Christian Ganz points out. He therefore recommends that the responsible politicians and administrators should first carry out a fundamental assessment of the status quo to develop a strategy for the preservation of the fabric of the bridges and an individual analysis of each structure, including a recommendation on how to preserve it. The starting point is a solid appraisal of the existing situation with a basic evaluation. Such an appraisal was carried out, for example, on commission for the city administration in Stuttgart: in a 50-page report, Dr. Christian Ganz and his team have analyzed the condition of 125 road bridges in the city and forecast the costs of maintenance. The city's civil engineering department can now consult this report in its future bridge maintenance planning. 

The recommended strategy is to group structures with a similar construction type or size, similar damage or load profile in clusters, and as far as possible to combine the refurbishment work on the bridges in each cluster. 

“As a rule, this could provide considerable synergies,“ the expert suggests. “In our work, for example, we refer to standards and research approaches developed by the Federal Highway Research Institute (BASt), and then we translate them into practical terms. Instead of simply collecting formulas or making calculations to the third theoretical place of decimals, we therefore focus especially on practical experience in structural engineering.”

Far-Sighted Preservation Strategies Are Essential

Cracks and corrosion are the most common weak points. On principle, every bridge in Germany is subjected to a general inspection based on DIN 1076 every six years. Like the grades that are given in schools, the inspection engineers award grades for structural stability, traffic safety and durability, and then the resulting data are automatically evaluated in an IT-assisted process which awards grades from 1 (very good) to 4 (insufficient) for the condition of the structure.

The central focus of all inspections is the specialist concept of a lifecycle analysis. In other words: “Every bridge is subject to processes of change which affect its structural fabric, load-bearing capacity and safety performance,“ Christian Ganz adds. In his view, with regard to the prioritizing of preservation work, this is an extremely important issue – but not the only aspect: traffic density also plays a major role. Is the bridge part of a main transport artery? How can ecological consequences be reduced, what can be done to augment social acceptance – for example by local residents or taxpayers? When addressing bridge preservation management issues, Drees & Sommer’s team of experts focus on sustainability guidelines, professionalism in contract management and the development of an individual preservation strategy.

Nuremberg’s Bridges: Strategic Maintenance Plans for a Solid Future

In Nuremberg in the Franconia region, many of the bridges which cross over roads or railways need to be maintained or refurbished. However, the Franconian metropolis is well prepared for this. The city of Nuremberg has a very good knowledge of its structures, largely because it has, inter alia, regularly compiled bridge reports since 2011 to present details of their structural fabric and condition to committees. The city administration has gathered all available data for around 300 bridges and prepared a strategic refurbishment plan. About 200 bridges – with an average age of 50 years and constructed with reinforced or prestressed concrete – are now in the second half of their total lifecycle, which is assessed at 70 years. 

But instead of making a global increase in the investment funds, Nuremberg focuses on very precise strategic planning. This is why the city has, inter alia, commissioned Drees & Sommer to develop a prediction tool for financial planning and further prioritization of measures, using the data of the past thirteen years. “Up to now it has been difficult to make dependable statements with a long-term perspective due to the existing age structure and the relevant development of the condition of the bridges, and this is where the prediction tool can be expected to help by optimizing preservation strategies for transport structures and streamlining the economic use of financial assets so that the necessary investments match the available resources,” comments Christoph Miller, a scientific associate with infrastructure responsibility for bridge construction and water management in the service enterprise for public spaces in the city of Nuremberg. This organization is a municipal enterprise of the city of Nuremberg which is responsible for areas such as the urban infrastructure.

Lawmaker Reduces the Building Permission Obstacles

The development of Germany's bridge infrastructure in the coming years requires both economic knowledge and engineering skill. This is reflected in the variety of bridge structure and construction types which exist in Germany. They include the full range, such as beam bridges, arch bridges, suspension bridges, cable-stayed bridges and truss bridges. 

Bridges can also be classified according to their location. Does the structure cross a valley, a hillside, a river or lake – or another traffic route such as a railway, canal or road? And finally, bridges consist of various components such as the superstructure and substructure, bearings, foundation and footing. And they are fitted with various additional elements for waterproofing, drainage, noise control and expansion joints between road sections. Differences in size, construction type, building materials and the surrounding topography only partly explain the sometimes very long periods needed for refurbishment or for demolition and the construction of new structures.

Another major factor can also be identified in sluggish bureaucracy. “With today’s planning and approval procedures, the refurbishment or extension of a bridge takes between five and eighteen years,” can be read on the website of the German government. Therefore, in 2023 the legislative body decided to completely eliminate the obligation to obtain permission for bridges which are extended in the course of a refurbishment project. However, before any approval application process begins, the developer must first make an appraisal of the project and define the priorities. Here, the responsible administration department must play its role.

The Strategic Bridge Preservation Program of the Federal State of Baden-Wuerttemberg

With this in mind, in February 2021 the Ministry of Transport of the federal state of Baden-Wuerttemberg commissioned Drees & Sommer to compile an analysis report on its approximately 7,300 bridges on national trunk roads and federal state roads. The report also covers the bridges which pose a special risk of stress corrosion cracking. In Baden-Wuerttemberg’s network of national trunk roads and federal state roads, these are 73 bridges. This form of corrosion can lead to a sudden failure of the prestressed steel reinforcements, even if there is no visible damage beforehand. Experts believe that this was the cause of the collapse of the Carola Bridge in Dresden on September 11, 2024. The 73 bridges with this suspected weakness are scheduled to be replaced by 2030. These bridges are part of the strategic bridge preservation program that the federal state is currently preparing, and which defines clear priorities.

For the years 2025 and 2026, the federal state has planned a total of 184 million euros each year for preservation work in the federal state road network, including bridges. The two-year budget, which is due to be passed in the federal state parliament, includes an additional 19 million euros specifically for the bridges in the federal state roads. This lays an important foundation for the goal of eliminating stress corrosion cracking. Of course, all of this cannot be done overnight. The four affected regional administrative councils have therefore agreed to introduce shorter inspection intervals, and where necessary to restrict the use of the roads – for example by imposing speed limits or load limitations.

From Decay to Virtual Remediation

The goal is to restore the bridge infrastructure step by step. Christian Ganz brings it to the point: “We hold the key to the solution”. Municipalities with a solid and strategic preservation management are able to efficiently and effectively manage maintenance measures and reduce financial risks. This involves a software-assisted calculation of the condition of all structures and a reliable investment needs planning. Regular reporting is required and all measures must be documented by the parties involved during implementation and realization: “Digital methods such as building information modeling, or BIM, also support the management of such large-scale projects. Structures and construction processes are simulated in detail in order to exclude planning errors. In addition, we participate, as a development partner, in the research project ‘HyBridGen - Hybrid Bridge Generator’, which is being funded by the Federal Ministry for Digital and Transport (BMDV). With the aid of artificial intelligence we are preparing plausible bridge designs on the basis of the existing routes and making use of geodata,“ Drees & Sommer’s senior expert concludes.