According to research led by Hussam Mahmoud, an engineer and Colorado State University associate professor in the Department of Civil and Environmental Engineering, climate change could accelerate the deterioration of aging U.S. infrastructure, which includes over 600,000 bridges.

The research has since been published by lead author Susan Palu—who recently graduated from CSU with a master’s degree in civil engineering—with co-author Mahmoud in PLoS ONE.

Climate Impact

Focusing on 80,000 steel girder bridges in the United States, Palu and Mahmoud chose to focus on the common design due to its frequently clogged expansion joints and regularly required maintenance. Additionally, expansion joints are directly affected by cool or hot air, which allow for the expansion and contraction of the structure.

Colorado State University

According to research led by Hussam Mahmoud, an engineer and Colorado State University associate professor in the Department of Civil and Environmental Engineering, climate change could accelerate the deterioration of aging U.S. infrastructure, which includes over 600,000 bridges.

According to CSU’s news release, when a joint becomes clogged, it can no longer allow the bridge to expand in the presence of higher temperatures. Due to this flaw, researchers reasoned that higher temperatures could lead to unpredicted thermal stress, which can cause buckling and cracking and would be worsened by bending from the weight of crossing vehicles in addition to axial loading from the restricted expansion.

In using projected temperature increases adopted by the International Panel on Climate Change in 2014 that predicted a “radiative concentration pathway” of greenhouse gas warming scenarios, the researchers considered four different seasonal scenarios in their study. Palu and Mahmoud chose to look at the temperatures were at the time of each bridge’s construction and the projected average temperatures for the years 2040, 2060, 2080 and 2100.

As a result of the study, the researchers found that bridges located in the northern portion of the U.S. are the most susceptible to more pronounced increases in temperatures, with the South- and Northeast regions being less affected by the impact of climate change.

“We as engineers must start to look beyond what we have initially been taught on how to analyze systems and start to think about what climate change is going to do to our understanding of component-level behavior and system-level performance,” Mahmoud said.

The researchers aim to rank bridges in order of necessary maintenance after accounting for climate change norms.