Problems loom for local infrastructure; ‘more insight needed’

Dutch infrastructure, such as bridges, needs assessment, maintenance, and eventually replacement. A large portion of the infrastructure stock was built shortly after World War II, meaning that the end of its 100-year lifespan is approaching. Moreover, the traffic that is running on the bridges and roads has increased sharply in recent years, and the load carried by heavy freight has increased. Action is needed. “Maintenance of major bridges and viaducts on the highways is regularly in the news, but we don’t hear much about local infrastructure, managed by municipalities or provinces,” says Yuguang Yang, associate professor of concrete structures at the Delft University of Technology (TU Delft). “Yet, major problems are looming at the local level as well.” 

Small government, complex infrastructure

That is why 4TU.Built Environment, a partnership between the construction-related faculties of the technical universities in the Netherlands, will be focusing on in the coming period. They will support local and regional governments in addressing the challenges surrounding infrastructure renovation. “At the national level, the Rijkswaterstaat (the national agency for infastructure, ed.) invests a great deal of time and money in monitoring and renovating infrastructure. For local governments, this is often more difficult. There is less capacity, both in terms of expert and financial resources. Moreover, the scale of the problem is often not really clear to local officials,” says Yang.

Despite operating with limited capacity, local and regional governments still have to manage complex infrastructure. “Large bridges are not only on main highways”, says Davide Leonetti, assistant professor of steel structures and structural condition monitoring at Eindhoven University of Technology (TU/e). Both Yang and Leonetti are part of 4TU.Built Environment Domain Acceleration Team (DAT) Infrastructure.

Concerns about the Nelson Mandela Bridge

The scientists mention the Nelson Mandela Bridge in Zoetermeer as an example. In late 2022, the bridge was completely closed after an investigation—in which TU Delft was involved, among others—revealed that the safety of the bridge is not sufficient considering the load that it needs to carry. “There was a visible crack at a critical location of the bridge that caused safety concerns, which triggered the investigation. In the worst-case scenario, the bridge could have collapsed,” says Yang. “Here, you can see that the municipality has few resources to come up with solutions quickly. That can affect the larger infrastructure network—in this case, highways—and thus create problems for the entire country.”

The municipality of Zoetermeer called in Rijkswaterstaat for assistance. Part of the bridge’s glass structure was removed, and a temporary bridge was built for cyclists and pedestrians.

Greater insight

The DAT infrastructure is currently exploring which tools can assist municipalities and provinces in identifying infrastructure issues early on and, where possible, resolving them. The exact approach is currently under discussion, but Yang sees three phases in which the DAT can contribute. First, he wants to provide municipalities and provinces with more information about the status of their infrastructure. Second, he wants to equip local and regional administrators with tools to analyze that information efficiently. Finally, he wants to propose a cost-effective solution to the involved entities if the analyses indicate that action is needed.

Different entity, different approach

According to Yang, there is a clear difference between local governments and the national level in terms of costs and staffing. “Locally, administrators often work with limited budgets, but allow a bit longer interruption of traffic. Therefore, it is possible to choose a more cost-effective solution that may have a greater impact on traffic. This is a slightly different approach than the one Rijkswaterstaat often takes for national infrastructure. A major highway cannot be closed for long, so it is important that renovations are carried out as quickly as possible,” he explains. That is why, according to the professor, it is important to analyze the right balance among all factors on a case-by-case basis.

Developing a method

What is scientifically required to strike this balance? “We want to develop a method that can be applied to different types of infrastructure and a wide range of materials,” explains Leonetti. Yang adds: “We may also be able to use AI to integrate existing online sources, such as photographic material, into the method.” Municipalities can then use the resulting information to better understand the condition of their infrastructure, gain an overview, and set priorities, enabling more targeted research later. 

On a smaller scale, TU/e is already working on a similar method in the SUBLIME (Sustainable and Reliable Macro Steel Infrastructures) project. This initiative primarily involves monitoring the condition of steel bridges to ensure greater reliability and, ultimately, sustainability. “The DAT aims to create a larger-scale version of this model. A comprehensive method suitable for various types of infrastructure made from different materials,” says Leonetti.

Scientific challenge

Focusing directly on helping municipalities and provinces is a relatively new approach for scientists. “It’s quite different from standard scientific research, but it’s very interesting to us because it has such significant societal importance,” says Leonetti. However, there is also a major scientific challenge behind this plan. “Developing a method to make informed decisions based on limited and rapidly changing data is, from a scientific perspective, perhaps even more complicated than building a large, complex bridge,” adds Yang.

If the methodology is ultimately put into practice, municipalities will have a better understanding of what kind of intervention to select, Leonetti notes. “This has economic benefits, because maintenance is carried out at exactly the right time. That way, you don’t apply expensive intervention to the bridge that actually still has some life left in it, and you also face fewer instances of sudden closures, which reduces traffic disruption and, consequently, economic damage. Insight into the condition of certain components is also beneficial from a sustainability perspective because some parts may last longer than expected,” he concludes.