Dr. Muntasir Billah
July 31, 2023
Canada needs billions in bridge repairs, and climate change will drive that cost up: UCalgary researcher
Ten years ago, Calgarians lived through a devastating flood that washed over several neighbourhoods along the Bow and Elbow rivers. Just a few short days later, a rail bridge over the Bow partially collapsed as a train crossed over it; this was later determined to be a result of that flood.
Dr. Muntasir Billah, PhD, an assistant professor at the Schulich School of Engineering, says events like this could happen more often, thanks to climate change.
Billah, with the Department of Civil Engineering, studies Canada’s infrastructure system. His main goal is to improve the resiliency of built infrastructure. Billah’s focus is on improving design guidelines to make bridges more resilient against both man-made and natural hazard events.
He says planning and building infrastructure now requires climate change to be increasingly factored in.
“We know that climate change is real; the data backs it up and, if you look into the climate-change pattern of Canada, Canada is warming at twice the global mean,” says Billah. “The implication on our infrastructure can be significant. Maybe we are not seeing it at this particular point, but, when we design bridges typically, we consider the design life of 75 to 100 years. Say, for example, a bridge which was designed 50 years ago; maybe it is now experiencing the impact of climate change.”
Bonnybrook Bridge collapse
The train bridge that collapsed back in 2013, the Bonnybrook Bridge, was 101 years old at the time, and it was later determined that the flood had scoured its foundation, leading to the collapse.
It’s not just occasional disasters like the Calgary Flood that could potentially play havoc with infrastructure. Billah says predicted future changes in global temperature and relative humidity could increase bridge-structure corrosion by up to 15 per cent if there was an average temperature increase of 2 C. He says this increased temperature has potential to cause buckling of bridge girders, as well as cracking and crushing of bridge decks.
The 2019 Canadian Infrastructure Report Card shows that more than 39 per cent of Canadian bridges are in poor or fair condition. The maintenance needed to bring these bridges up to the current standard is estimated to cost around $21 billion, but Billah warns that this cost is likely to be higher due to climate-change induced events.
Extreme weather equals infrastructure stress
“The important thing that we are looking into is not only making our new designs effective, but also how can we adapt our existing infrastructures towards the impact of climate change, which has not been looked at from a holistic approach so far,” Billah says. “We are trying to look at this from the climate-change point of view: how, as [engineers], we can implement new materials and design tools and how we can make our existing and new infrastructure resilient to climate change.”
Billah says constant freezing and thawing in wintertime could also contribute to the deterioration of bridges. As the water from snow melts, he explains, it sinks into the concrete and then, once it freezes again, it expands, causing the concrete to crack and make room for further deterioration.
Extreme summer heat, which most building materials similarly were not designed for, can also cause concrete to expand. “For any structure, we design it for a certain temperature range and, if it exceeds that, then it causes additional stresses or additional forces to our structural members. And that creates more loading onto our structures and creates problems for our infrastructures,” says Billah.
Billah and his team are currently examining different regions in Canada, including their temperature-change history and temperature forecasts.
From there, Billah says there is not one single solution, but rather many potential solutions, depending on the environment.
For example, he says, his team is currently trying out the effectiveness of different metals such as stainless steel (which is less susceptible to corrosion), as well as different types of concrete.