Typically, Muench says, the solution isn’t too complicated: simply build the infrastructure higher. But engineers can’t build roads and bridges to survive every disaster, which would lead to expensive, overbuilt projects that “would take generations to finish,” Muench says.
‘Rice Krispie’ Roads
When engineers rebuild roads from scratch, they have also started using different materials to account for the possibility of a lot of water arriving very quickly. Over the past decade, road builders have increasingly installed more permeable and “spongy” roads.
Pervious concrete, unlike regular concrete, typically excludes sand from the typical “gravel, sand, cement, water” recipe. It also has a lower ratio of water to cement, which creates a thick paste before drying. “It’s like caramel popcorn or a Rice Krispie bar,” says Nara Almeida, who studies the material as an assistant professor in the civil engineering program at the University of Washington Tacoma.
On normal concrete roads, water accumulates and accumulates, and the stagnant water ends up damaging its various layers, and especially the critical underlying ones, which support the heavy loads of vehicles. But the greater porosity of permeable concrete allows water to flow through the material more easily, so it can reach the ground and be absorbed by it, an interesting feature for roads subject to high humidity.
Pervious concrete has its disadvantages. It’s weaker than regular concrete, which means it’s better suited to sidewalks, parking lots, and streets with little traffic than interstate highways that expect a lot of heavy trucks. (Investigation (The task of reinforcing the material with steel, natural, glass and synthetic fibers is being carried out.) Its porosity means it is not ideal for cold climates, where water can seep in, freeze and break down the material inside. Concrete also needs regular pressure washing or vacuuming to “unclog” it of the type of material often found on the road: dust and leaves. Because states sometimes have to change suppliers and processes to use the newer material, projects can cost them more. But some places have placed the material on the shoulders of interstate highways, Almeida says, which are much less likely to take regular hits to the tires.
Ultimately, however, there’s not much that can be done when a huge volume of water flows rapidly across a road or bridge base, what engineers call “undercut.” “We’ve all played in the backyard with water and hoses; it’s very damaging,” says Muench, the engineering professor. Part of climate resilience is planning ahead and placing quick-fix materials nearby so communities can rebuild quickly.