Could climate change prediction models and regional data collected by cities help ensure the safety of infrastructure in the future? Securing infrastructure like bridges and making them weatherproof is pretty important work. However, with more extreme weather events predicted for the future, how can engineers be sure their bridges will stay standing?
Engineers have life-cycle projections for bridges they have constructed. Although in a world threatened by more fierce climate events, the life cycle of bridges could be under threat. Predictive and preventative maintenance on bridges could be done in a much more informed manner if engineers were aware of future climate events and how those events could damage the structural integrity of bridges.
A less predictable threat to the structural integrity of bridges is scour. Scour is the erosion of soil around the foundation of a bridge caused by fast-moving water underneath it —typically during floods.
Scour is the most significant contributing factor to bridge failure in the United States. According to Ayres Associates, 82% of the 600,000 bridges in the National Bridge Inventory in the United States are built over waterways. With more and more climate events occurring globally, the likelihood of flooding, and in turn, scour increases.
As a consequence, engineering bodies are looking to academia to assess the impact of climate change on bridge safety. Lehigh University, a private research university in Pennsylvania, has put researchers David Yang and Dan M. Frangopol on the case.
The two researchers have published a paper in the ASCE Journal of Bridge Engineering under the title: ‘Physics-Based Assessment of Climate Change Impact on Long-Term Regional Bridge Scour Risk Using Hydrological Modeling: Application to Lehigh River Watershed.’
Research associate in civil and environmental engineering at P.C. Rossin College of Engineering and Applied Science, and co-author of the report, David Yang, said, “We know climate change will increase the frequency and intensity of natural hazards like hurricanes, heatwaves, wildfires, and extreme rains.
“For this paper, we’re looking at increased temperature as well as increased precipitation and their impact on bridge safety. The challenge here was that we didn’t know how to quantify those impacts to predict scour risk.”
Therefore, the researchers looked to climate data to see if they could produce a predictable model for structural safety in the face of climate events.
“We took a holistic approach. It started with a global climate model that was downscaled to regional hydrology. Then we used structural engineering to get the failure probability of a structure in a future flooding event,” Yang explained.
“From that, we could assess: does this structure failure pose certain risks to a community? So our model included these four steps of climatology, hydrology, structural engineering, and risk assessment.”
They conducted research and developed their own model by using flow discharge measurements in their local river, the Lehigh. They inserted global climate models as developed by the Intergovernmental Panel on Climate Change (IPCC), and added historical bridge foundation depth data in their local river, provided by the National Bridge Inventory. What they found was that flooding was becoming more common, and doubling in frequency as time went on.
The question now is how to export this model for other regions and make it useful for the engineering industry as a whole. Engineers will be better equipped to mitigate risk and plan for disaster far better than in the past with these kinds of models.
“You need to know the location of the bridge. For some communities, the failure of a bridge could be disastrous. For others, a bridge may not be as critical,” Dan M. Frangopol, an affiliate of Lehigh’s Institute for Data, Intelligent Systems, and Computation (I-DISC) said.
“This model helps you make that kind of decision because risk is not only based on safety but also on the consequence of failure. You might have two bridges at the same probability of failure, but the consequences of that failure could be very different.”
Civil and structural engineers can be sure that there will be more data-driven mechanisms that challenge their safety checks and balances in the future. With historic trends and future prediction models combined, there will be no running away from establishing meticulous safety procedures on bridges (their foundations in particular) and other infrastructure.
“Predicting the Impact of Climate Change on Bridge Safety.” ScienceDaily, ScienceDaily, 9 Oct. 2019, www.sciencedaily.com/releases/2019/10/191009075326.htm.
“What Is Bridge Scour? Why Should You Care?” Ayres Associates, 13 Sept. 2018, www.ayresassociates.com/bridge-scour-care/.