They're not just about connecting roads, either. They connect people, too. Bridges are the shining example of German engineering. They span rivers, valleys, villages and even the sea, carrying millions of vehicles from A to B every day. To the shops, to work or to visit your in-laws in the countryside. Chances are, your next vacation will take you over at least one of Germany's 40,000 freeway and federal highway bridges.
Anyone who follows the media closely knows that German bridges are not in good condition. Mouldering concrete, gaping cracks, severe speed restrictions and the sign "Caution: Bridge Damage". And this isn't a new issue. In this blog post, we're going to look at some of the issues with German bridge construction. How is it that so many German bridges are in such a poor state of repair? Is there still a way to save German bridges?
History of Bridge Construction in Germany
Hardly any other structure has accompanied us humans for as long as bridges. The first bridges were simple logs thrown across a stream, and then came the first wooden fortifications. Whether made ropes, wooden slats, or large stones rolled into a river – a safe crossing connected families, villages, and later entire towns or countries.
The Romans were the first to provide permanent solutions on European soil. As trade in goods and military troop movements grew, so did the demand for bridges.
The wooden bridges were replaced by impressive stone arches. It wasn't long before bridges were more than just tools for military and trade purposes. They became status symbols of power and influence.
Julius Caesar himself wrote about a 400 m long bridge he built over the Rhine to show off his power. Unfortunately, Roman bridges aren't preserved in Germany today. But even after the Romans, German bridge construction continued to impress.
It wasn't unusual for regular folks to wonder: How did they manage to build a building like this? How can it be made to stand firm? Master builders, and later architects and engineers, developed ever faster, more durable bridges that could only be brought to their knees by a flood that would have been unimaginable a century ago. This led to some fascinating stories and legends.
German Bridge Construction: Devilishly Good?
In Regensburg, for example, a rivalry between master builders is said to have been the inspiration behind one of these legends. The bridge builder and the cathedral builder made a bet as to which structure would be completed first. It didn't take long for it to become clear that the cathedral was being built faster.
The bridge builder then had a change of heart and offered the devil the souls of the first three creatures to cross the bridge in exchange for winning the bet. Ultimately, the master builder had two roosters and a dog transported to the other side after the bridge was completed. So he'd outsmarted the devil.
In just 11 years, around 40,000 m³ of stone was used for the bridge. That's 70,000 tons of rock. That's roughly the same weight as a modern container ship. Nobody could really explain how he did it, so the legend of the pact with the devil was born. You can still see a statue commemorating this story today. The statue of the "Brückenmandl" is located in the middle of the bridge, overlooking the cathedral. It's as if it's still making sure that the devil actually keeps his side of the deal.
In fact, such devilish legends in connection with bridges are not so rare. Over the years, bridges that were actually impossible to build were often referred to here and there as the Devil's Bridge. One of these devil's bridges, probably the most famous, is located in Kremlau on Lake Rakotzsee. With an incredible length of 34 m, it spans the entire lake in a narrow arch. An impressive span for a single arch of a stone bridge.
Building such a steep bridge was simply unimaginable at the time of its construction between 1863 and 1883. So it was popularly decided that the devil must have had a hand in this too! Legend has it that anyone who crosses the bridge will die. Not only for this reason, but above all because of its almost fragile silhouette, it is forbidden to enter the bridge.
Modern Bridge Construction
As time went on, the demands on bridge construction changed a lot. Stone bridges could only span a larger river if they had lots of individual arches. This made shipping, which was a really important part of trade at the time, a bit of a problem. Meanwhile, the industrial approach to construction opened up new possibilities.
It wasn't long before the first bridges made of cast iron, and later steel, were built across the Germany's most important waterways. Longer spans, faster construction times and less material consumption: that's how modern bridges were born. As industry grew in Germany, so did the need for the freight and passenger transportation. A lot of drawbridges were built that could be opened and closed again for shipping traffic.
The majority of bridges we can admire today were actually built relatively recently. Most of them are made of steel and concrete. It's not just rivers that can be crossed in a short time, but also entire valleys and gorges.
Many of these concrete structures seem a bit clumsy and unimpressive. While they may not be the most aesthetically pleasing, they more than make up for it with their impressive engineering feats. Hundreds of thousands of vehicles cross these German bridges every day. From leisure vehicles to commuters and large HGVs.
Unfortunately, this is often what causes them to fail. Even these huge concrete structures are not invincible. A well-known German bridge recently showed us just how true this is.
Collapse of Carola Bridge in Dresden
It's September 11, 2024, middle of the night in Dresden, the capital of Saxony. The Elbe river winds its way through the city, surrounded by historic buildings and parks. It is one of Germany's largest and most important rivers. The Carola Bridge spans the Elbe. The Elbe has had a bridge with three long concrete cables stretching between the two banks since 1971, and until recently, tens of thousands of people crossed it every day.
Shortly after three, there's a huge crash. A section of the bridge, which is used by streetcars to cross from one side to the other, collapses. It just happened. Without any prior warning. Fortunately, no one was injured. It could have ended badly. At first, the experts thought the news about the collapse of the Carola Bridge was a joke – but that changed when some of them stood in front of the wreckage themselves. But how could something like this even happen? How could the Carola Bridge collapse?
Why did the Carola Bridge collapse?
It was thought at first that the new streetcars, which had been running over the bridge for several years, were maybe just too heavy. This extra weight would eventually cause the material to wear out. As it turns out, the new streetcar models aren't any heavier than their predecessors; they're actually somewhat lighter. It wasn't because of too much weight.
The investigation is still ongoing. It seems that corrosion may be caused by a reaction between the reinforcing steel and chlorine. What does that means? The collapsed section wasn't covered in asphalt like the other two bridges, as it was used by streetcars to cross the Elbe.
The streetcar tracks were laid directly on the bridge structure, without a protective asphalt layer. Even small leaks probably let de-icing salts get into the concrete in winter. The chlorine in the salt caused the built-in steel to rust and become brittle. The latest investigations show that around 30-40% of the installed steel was already damaged by barely visible cracks before it was installed.
It seems that the critical point was in a joint above one of the piers, which you can see on the left in most of the pictures. The tendons were right under the road, so they weren't as protected from salt as they should have been. It seems that rusting through at this point is the most likely cause of the collapse of the Carola Bridge.
Although there wasn't much de-icing salt used as road salt on the Carola Bridge, it's possible that salt was sprayed onto the tracks from the adjacent roadway. Through the tyres of passing cars.
Could the collapse of the Carola Bridge have been prevented?
In one of our last podcast episodes, we had a bridge construction expert as a guest. Prof. Dr.-Ing. Hans Bulicek from the TU Deggendorf made a good point in our conversation: the reputation of German engineers, especially when it comes to bridges, has taken a hit internationally because of this incident. But what actually happened? Could the collapse of the Carola Bridge have been prevented?
Efficiency and safety are the most important aspects in maintaining the infrastructure: not necessarily, but unfortunately very often in this order. Unfortunately, the public only listens to engineers when something happens. The fact is that no bridge in Germany has ever collapsed while open to traffic.
Prof. Dr.-Ing. Bulicek also explained the special features of prestressed concrete bridges, such as the Carola Bridge. Such old bridge structures do not show any signs that something is wrong before they collapse. They collapse of their own accord, without warning. There was no traffic load, no flood, no strong wind, and no earthquake at that time of day. No pier was undermined, nothing caused the Carola Bridge to collapse.
No one expected such a collapse. If there had been the slightest hint, the bridge would have been closed and thoroughly investigated. This corrosion damage under the deck on the tendons would simply not have been visible without tearing up the surface layer.
Nobody tears up an entire deck without a concrete suspicion. Regular inspections of the bridge would therefore not have revealed any corrosion. In fact, the other two parts of the Carola Bridge had been renovated – recently.
An expert report had shown that the tramway deck was probably in the best condition. The two carriageways were to be renovated first, and then the so-called Train C of the Carola Bridge was to be renovated. The renovation of the collapsed section was therefore scheduled for January 2025. There was even a tender for the work. Unfortunately, it came too late.
What has the industry learned from the Carola Bridge collapse?
The collapse of the Carola Bridge has attracted national and international attention. The engineers responsible, but also the profession itself, have come under scrutiny. Did German engineers simply fail?
It's not quite that simple. There is a problem not only with the Carola Bridge in Dresden, but with bridges and buildings in general: politics. Or to be more precise, the allocation of budget funds and budget planning. The expansion of further long-distance transport routes has swallowed up an immense budget of billions of euros every year.
Heavy-duty traffic in particular has increased many times over since the border was opened in 1989—and is still growing strongly year on year. New highways have been built and existing ones have been extended. Bridges, many of which were built before 1985, were neglected for a long time. And they just kept on getting older. They were simply not designed to handle the increasing load.
The collapse of the Carola Bridge shows us exactly what this problem looks like. Sometimes, profit is put before safety. It's sad, even frightening, but it's been this way in construction for a long time. If we'd spent more money earlier and followed the experts' advice, we could have saved the bridge. Damage to it had been known for more than 11 years, but no one wanted to do anything about it.
In the long term, though, it would have been necessary to replace the whole supporting structure. At the end of the day, a good sealant or a fresh coat of paint won't change rusty steel. The debate on how to improve the way of rating bridges has now reached Berlin. But the thing is, politicians are discussing this among themselves, not engineers. And that's exactly the issue.
The collapse of the Carola Bridge should be the final push for engineers to be heard. They're experts in their field, so they should be listened to more. Their opinion should be given more weight than tax-saving plans.
We shouldn't have to compromise on road safety, including when crossing bridges, because of a political austerity plan. Not in an industrialized country like Germany. It should depend solely on the opinion of experts, their many years of experience, and a good dose of common sense.
Condition of Germany's Highway Bridges
It's not just bridges like the Carola Bridge that are a problem in Germany. Nor are the smaller bridges used by tractors to access their fields. No, the biggest and most frightening role is played by Germany's highway bridges.
Autobahn GmbH, the company responsible for expanding and maintaining Germany's long-distance road network, published a devastating forecast this year. According to current calculations, there is a shortfall of around € 5.5 billion to ensure the planned measures to maintain the long-distance transport network and modernize highway bridges for the years 2025 to 2028.
There are plans to renovate 400 of Germany's 28,000 highway bridges over the next few years. A further 3,600 bridges could also do with a major overhaul, as some are visibly damaged. Many of them were built before Germany became one of the world's major hubs for long-distance and freight transport. But even for these 400 bridges, there is no money. A quick solution is needed. But which one?
Germany: Country of Ailing Bridges
Many Germans and other drivers on Germany's highways are familiar with this traffic sign. The red warning triangle with the black exclamation point. And underneath the words "Bridge Damage". Usually accompanied by an often considerable speed limit.
Ailing German bridges are put on the renovation list after a risk assessment. But the list is long. And until the budget and renovation plans are finalized, their safety must be guaranteed. This depends on the results of the inspection.
The Rahmede viaduct, for example, had to be closed in 2021. The damage to the supporting structure of the highway bridge, which was opened in 1968, was too extensive. Even years before, it was only passable with restrictions. Speed limits of 80 km/h, distance regulations, no overtaking for lorries and a ban on heavy-duty trucks.
A laser measurement in December 2021 revealed severe deformations and the bridge was immediately closed to traffic. The bridge was demolished in 2023 and a new structure is scheduled for completion in 2026.
Trucks: Hooligans in Highway Traffic
We have already mentioned that many of today's highway bridges were designed and built before 1985. Times have changed dramatically since then. Take the Rahmede viaduct, for example. When it was planned in the 1970s, the daily traffic of around 24,000 vehicles was assessed.
For most highway bridges in Germany, these values are similar. And today? Depending on the region and the junction, current data far exceed these initial values. Before the Rahmede viaduct was closed, more than 64,000 vehicles, almost a third of them trucks, crossed the German highway bridge every day. In other parts of Germany, the difference between then and now is even greater.
With the opening of the border between the West and East Germany, the united country quickly developed into one of the most important transport hubs in Central Europe due to its central location.
Figures from the German Aerospace Center (DLR) show that German road freight traffic has doubled in the last three decades, from 245.7 billion tonne-kilometres (tkm) in 1991 to 498.6 billion in 2019 (before the coronavirus pandemic). This means that more than twice as many goods are now transported through Germany than in 1991, including on German highways.
Freight transport on German roads now accounts for almost 75% of all freight transport. This makes trucks the most important means of transport for national and international goods traffic in Germany.
And these trucks are on German roads every day – at least except of Sundays. A day when roads, bridges, and drivers can breathe a sigh of relief. But the German highway bridges are not only groaning under the sheer number of vehicles. Not only are there more and more trucks on German highways. They are also getting heavier.
At the end of the 1950s, the permissible gross weight for trucks was 24 tonnes with an axle load of 8 tonnes. As of 1968, the first 38-tonne trucks were permitted. Today, four-tonne trucks with an axle load of 11.5 tonnes are the absolute standard for freight transport throughout Germany. Larger trucks only drive with special permission.
At least in theory. Anyone who has driven on German highways knows: Never trust a truck! Elephant races in the second and third lane because someone is driving at least 2 km/h faster in the middle of a no passing zone for trucks. Or two trucks racing each other at almost 80 km/h in the middle of a Zone 60 Construction to see who gets to the other end of Europe first.
Many drivers do not follow the rules. It is no coincidence that thousands of trucks are pulled over every year during routine police checks on German highways. The result: exceeded axle loads, too high gross weights, excessive speeds, big egos, and insufficient distances.
It is not only the truck drivers who have to obey the law who suffer, but also the angry car drivers and—often forgotten—the overloaded bridges. It is not for nothing that the first measure taken on highway bridges is to narrow the lanes. Trucks overtaking bans, speed limits, distance regulations: If only everyone would stick to these.
Nevertheless, in the wake of the coronavirus pandemic, the truck toll was reduced. To keep the economy going. More trucks at the expense of the highway bridges. Once again, thinking in terms of economic profit wins out over safety and common sense.
With more tolls on foreign trucks, we could repair more bridges more quickly. After all, they are forced to use our roads. Or what about a toll for domestic trucks? We'll get to that later.
So they wait and play until another bridge collapses. But this time with considerable personal injury. And then the engineers will be blamed again. You've certainly noticed: Something is going wrong in this system. So let's cut to the chase.
Why have so many bridges in Germany not yet been renovated?
We have now discussed some of the reasons why Germany's highway bridges and their smaller cousins are in such bad condition. But is it really necessary? Around 4,000 highway bridges are in urgent need of renovation. And we're not even talking about ordinary bridges in urban areas or on federal motorways.
At the rate of 400 bridges a year, this will take at least ten years. And by then, more German highway bridges will have fallen into disrepair. A never-ending cycle. We need more money to maintain, renovate and—if possible—modernize German bridges. But where is the money going to come from?
Preservation of Bridges: Lack of Political Interest
The federal budget for 2025 has recently been adopted. Which areas will receive how much money? Where will there be savings, where will there be generous increases? And where are the greatest needs? We have already discussed in this article that the financial gap in the maintenance of German bridges is particularly large.
Unfortunately, there isn't any more money that can be made available. There's already €9 billion set aside for bridges and highways. It doesn't sound bad at first, but we've already read about it: Autobahn GmbH reckons there'll be a shortfall of €5 billion for 2025-2028.
The federal government is setting aside double the €9 billion for next year to expand the rail network. Staff of our favourite (and unfortunately almost only) railroad company will probably thank them – presumably with another increase in ticket prices. On top of that, more railways mean more chances of delays.
But let's not forget that 75% of freight traffic runs over German roads and bridges. In terms of image and sustainability, investing in rail is not a bad thing, but it doesn't help our bridges much unless they carry at least one rail train. It's still not clear whether this was the right decision.
So is there just not enough money in the budget to invest more in German bridges? Sadly, it's the complete opposite. The transport sector even had its best year ever in terms of revenue. The German budget was delighted to receive €33.2 billion in taxes and levies for diesel and petrol. The truck toll brought in €15 billion, which is twice as much as the previous record. On top of the €1.5 billion in taxes from air traffic, around €50 billion was collected from transport-related taxes alone.
And just €9 billion of that actually goes back into maintaining the roads and bridges. How can that be? It's a shame that not all of the money we pay in transport taxes is actually reinvested in transport. Instead, the money is used to cover other budget shortfalls.
Politicians are pleased about the increase in tax revenue from the transport sector, which can then be invested in other areas. It seems like bridges are not a top priority. It's tough to win an image prize with highway bridges, and it's even tougher to win votes. And this isn't a new thing – it's been going on for decades. It's been a long time now that savings have been made on German bridges.
But a lot of Germany's economy depends on making sure they're secure and that they're kept in good condition long-term. As the saying goes, you only realize what you've lost when it's gone. Or when the first highway bridges like the Carola Bridge collapse, and we have to ask ourselves the question again: Where are our engineers? By then, politicians will have moved on from them.
Modernization Backlog for Highway Bridges: No Construction Sites!
Have you ever driven through Hamburg? In the last 10-15 years or so? If so, you'll probably have an idea of what's coming. It seems like this city is one big construction site! Just imagine Hamburg on a larger scale – that's Germany. If you've spent a few hours on the German highways, you'll know that roadworks are a certainty.
There are over 2,500 bridges in Hamburg, making it the city with the most bridges in Europe. Just imagine it: 500 of these 2,500 bridges have to be closed and then renovated within two years. It would be utter chaos on the roads. There aren't many detour options, traffic jams, noise and exasperated drivers of major German car brands honking their horns, unable to make it to the company Christmas party on time. It's almost worth trying the train again, don't you think?
We face a very similar problem when we look at the need to renovate German highway bridges. We can't renovate or ultimately demolish and rebuild as much as we would like – or should. Highway bridges often cross large valleys or rivers. Or they cross entire streets below.
We're already having to take a long-distance detour via trunk roads. If a new bridge is built and traffic is diverted via a federal highway for the usual 4-7 year construction period, it's likely that the federal highway will need repairs just as urgently afterwards. It takes a lot of planning to repair or renew bridges. This calls for a lot of experience and personnel, as well as a significant financial investment.
All of this has been overlooked for decades. There's been more focus on expanding bridges and roads than on maintaining them. In the world of housing, we often talk about a backlog when it comes to modernization or renovation. Something similar has happened here too, and it'll be a while before we get a solution.
Future Plans: Safety of Bridges in Germany
What's the best way for Germany to solve its bridge dilemma? Not at all in the short term. We're already knee-deep in the political and financial quagmire, so that's not an option. Ideally, politicians would start paying more attention to the bridges again in the long term. And not just when they're looking for a new way to cut spending in other areas.
Especially in view of the Carola Bridge collapse, people are paying a lot of attention to the bridges in Germany. What happens next? Are the bridges still safe? Can I still drive over a highway bridge with a "Bridge Damaged" sign on it without a second thought? Politicians have to respond, of course, as they have the greatest influence.
There's still a lot of debate about how we can make the bridges safer in the future. The rating criteria for bridges are going to be updated and, if needed, made stricter. In our podcast episode on the safety of bridges in Bavaria, Prof. Dr.-Ing. Bulicek explains how such a rating works and what the individual results mean for the future of a bridge. You'll also get the lowdown on what goes into building bridges and his thoughts on why German bridges are in such a bad condition.
Apart from a revision of the rating criteria for bridges, there are also discussions about how they'll be financed in future. As we all know, there's a big shortfall in the budget for maintaining bridges and roads. It's not easy to get money back from traffic, so another option is to bring in private investors.
Anyone who knows a thing or two about the construction industry is feeling pretty uneasy right now. And it's just in time for Halloween! We're looking at setting up an investment fund, which is going to be mostly funded by private investors. In the next few years, this fund is going to be used to modernise and maintain bridges and roads.
It sounds good in theory, but it's actually a dark sword of Damocles. And it's always there at the back of our minds when we think about such a project. Imagine that someone with a lot of money donated some of it to this fund. That would be great! But this person might also be the CEO of a large brewing company that exports beer throughout Europe.
They agree to invest a lot of money and sees a good opportunity for themselves. About 80% of goods of this company are shipped by trucks from Germany all over Europe, often with foreign transport companies. So they make a demand: The reduced truck toll shouldn't be increased any further. It would be great to have that money to spend on fixing up some bridges that trucks use every day for this company.
On top of that, this person and their other wealthy friends in the same lobby are trying to stop preliminary discussions about a truck toll that would harm domestic trucking from getting too far along. The state will give in at some point. So this investor, along with their friends, is using an absolute nemesis of our economy: lobbying. When private investors or individuals have a say in how our economy and infrastructure are run, it can lead to problems.
In a nutshell, lobbying is the enemy of progress. Money plays too big a role too fast, and politicians often just shrug their shoulders. You don't win votes by fixing roads and bridges. And the maintenance of our infrastructure often gets lost in the public interest.
After all, the media don't or hardly ever report on it either. And if they do, topics such as the state of German bridges in our fast-moving world disappear within a few days under the rubble heap of everyday media madness.
So, what can we do about it? We have to keep flagging up the issues in the construction industry. The problems are few and far between, and only a small number of engineers are actually to blame. Instead, we have to keep pointing out the mistakes in the system itself.
The construction industry needs to modernize. It needs to make progress and, at the very least, be able to move away from political lobbying. Ultimately, we all want to cross the next bridge safely. Or that our Christmas presents will be under the tree on time. Without the hassle of broken glass on poorly constructed country roads and a week's delay due to closed bridges.
Conclusion: Ailing Bridges, Crumbling Concrete
The logo of Dlubal Software features a bridge as its main component. Bridge construction is seen as the pinnacle of civil engineering. This cable-stayed bridge shows our passion, which we put into our structural analysis software every day.
In the future, we'd like to see construction returned to the experts. Into the capable hands of the approximately 2.6 million people in the construction industry who make sure our buildings are safe every day. Our engineers should be listened to more often. It's not just when a bridge collapses, but in general. They know what our bridges need better than anyone else.
Let's let the engineers do their job and support them instead of putting more and more obstacles in their way. To be honest, we love bridges. And we'd love to be able to preserve them for the future. As a great example of German engineering, as the linchpin of our economy, and as a supporting pillar of our country's infrastructure.