How to protect critical road infrastructure?

The pictures went around the world when the Morandi highway bridge collapsed in Genoa during a violent storm in August 2018. The accident, which claimed the lives of 43 people, clearly demonstrated the importance of safe and resilient transport infrastructure systems. Therefore, the European Commission attaches highest priority to the protection of critical road infrastructure. However, the focus is not only on systems that assess the condition of such critical structures in terms of age and wear, for example, but also on solutions that make road infrastructure more resilient, so that it can respond effectively to unexpected events. We interviewed Alexander Dahl from the PTV Research Team, who is currently conducting research on this topic as part of a project funded by the German Federal Highway Research Institute (BASt).

Resilience currently seems to be a real buzzword. Resilience to Corona, to climate impacts, or resilient cities – what does resilience mean in terms of road infrastructure?

Alexander: The concept of “resilience” is not new in the transportation sector. Our research team has been working on this topic for at least ten years and has been involved in many exciting projects concerning the protection of critical road infrastructure. For example, U-THREAT – a project dealing with the resilience of subway systems. Or Skribt(+) focusing on the protection of critical tunnels and bridges.

In principle, we analyze how well transportation infrastructure can cope with negative effects caused by disruptive events, or how to enable rapid return to service. If critical route elements are not available for a longer period of time, this can ultimately lead to high macro-economic costs. We were involved in a number of projects, such as RITUN, where we used PTV Visum and PTV Validate to quantify the economic costs.

What kind of disruptive events are we talking about?

Alexander: We are talking about events that are unpredictable and therefore also occur quite rarely, for example, due to natural phenomena, human-induced changes, or technical failure. This could be the accident of a fuel tank truck carrying highly flammable materials in a tunnel, terrorist attacks, or extreme weather conditions, such as high winds at bridges or landslides caused by heavy rain.

You are currently working together with the Swiss consulting firm EBP Schweiz AG on the project FE69.0005 “Optimization and further development of action tools designed to assess the resilience of transportation infrastructure” initiated by the German Federal Highway Research Institute BASt. What is the purpose of this project?

Alexander: The aim of the project is to provide road construction authorities or other competent agencies with a software tool that helps them prepare for hazards.

The tool is designed to enable users to analyze how resilient a specific route section is to a wide range of disruptive events and to identify suitable measures to enhance resilience in a targeted manner. Possible actions include: threat mitigation, optimum adaptation or fast recovery.

EBP had already developed the basic version of the software during a previous project. Now, the task is to further develop it in terms of methodology and to expand the scope and measures. Currently, the tool is limited to the highway network; but it is planned to include other transportation modes, such as rail and waterways.

Can you give an example of such an analysis?

Alexander: Let’s take the example of a bridge exposed to strong wind currents.  Can it withstand these high winds? Could the vibrations be too strong causing the bridge to collapse? Could high winds affect vehicles on the bridge? Could a vehicle be blown off course, for example? Is it necessary to close the bridge at a certain wind speed?

Planners can then take appropriate measures in terms of infrastructure (the structure itself), management or operation. For example, what do contingency plans look like if the bridge must be closed? What are the bypass options? Do we have to define a system of detour routes, as we know it from highways, and signpost it in advance for emergencies?

So the tool is mainly designed to analyze and assess bridges and tunnels?

Alexander: Tunnels and bridges are key elements of our road network. So, it is of course a lot more dangerous, if a truck carrying hazardous materials catches fire in a tunnel than on the open road. But incidents can also occur on free route sections, such as flooding due to heavy rain or landslides, for example. Only last summer, the A8 motorway near Rosenheim in Germany had to be closed due to flooding after heavy rainfall. We are all aware that such events will occur more frequently due to climate change. In view of these developments, far-sighted concepts that help enhance resilience and thus protect critical infrastructure are now more important than ever.