Why roads in the Pacific Northwest buckled under extreme heat

Some roads in the Pacific Northwest were damaged by last weekend's deadly heat wave. In blistering heat, workers ventured out to repair cracked asphalt and concrete byways. To ensure that steel drawbridges wouldn't collapse under the heat, water was used to douse them with water.The heat dome, which sat above the region, put roads through a rigorous stress test. Some of them couldn't withstand record-breaking temperatures for multiple days. This has happened in Washington, Wisconsin and South Dakota before.Here's an example showing how heat can cause road pavement to buckle. Our crews are busy fixing SR 544 in Whatcom County and trying to open it by the afternoon. https://t.co/53XoBDBOMZ Traffic (@wsdot_traffic), June 28, 2021It doesn't matter if you want something to work at very high temperatures. Steve Muench, an assistant professor of civil engineering at Washington University says that this is not the problem. The problem is that current heat doesn't meet engineering expectations. This larger problem can only be solved with engineering, planning, public willpower, and a lot of public willpower.These roads can't withstand the heat.Different types of roads react differently to heat. The roads in the United States are usually made from asphalt or concrete.Muench states that concrete roads are usually made from portland cement. It is formed into large slabs that can measure approximately 15 feet in length and 4 feet in width to make a road. These concrete slabs expand and contract with temperature fluctuations. The cement's composition determines how much it expands or contracts.All of this is normal. The average driver will not notice the difference in expansion and contraction between slabs. When it is hot and humid, concrete slabs can become too narrow, especially if sand or other debris gets in between them.Heat equals expansion. Here's a view of a concrete panel that popped out on NB I-5 near Tukwila (I-405). Crews are working to remove the panel damaged and put it back in. There is no time estimate for opening the ramp and lanes. There is not much backup at this time. pic.twitter.com/OLd1Ewf6Kt (@wsdot_traffic), June 28, 2021It expands to the extent that it touches another slab when it is really, really hot. They push against each other, and there's no room for expansion.Asphalt is an entirely different beast. Asphalt is a viscoelastic, temperature-dependent material. Muench states that asphalt is fluidier the hotter it gets. Asphalt roads that are too hot can turn to Play-Doh and become brittle or deformable, creating ruts for trucks and cars as they drive over them.Both concrete and asphalt roads can be made to withstand heat. Muench states that we already know how to modify materials to perform in hotter environments. Phoenix isn't falling apart, it's not Armageddon because it's hotter.Problem is, when these roads were built in Washington, they used those materials and design techniques. Phoenix doesn't get as hot as Washington so it was unnecessary to consider extreme heat. This may be changing.Prepare for a future that is different from the pastEngineers can use historical weather records to determine what is normal when designing roads. What is the average amount of rain this area gets? What is the temperature range? What is the likelihood that the river near you will flood within the next 50-years? This information will help engineers choose the right materials and designs. It might not be enough.You need to be careful about the climate change and ask yourself if you are really relying on past information that may not be relevant anymore. Muench suggests that I should design it based upon what we see for the future.Roads are durable and can last a lifetime. Therefore, it makes sense to plan for the future. Engineers can use climate modeling to predict the future and plan for it.Even roads based on these models will not be perfect. It is impossible to design for all. Muench states that some things can cause damage to your infrastructure. No matter how well-designed, things can be damaged by a major storm, earthquake, or other natural disaster. Muench said that at that point, the question is how to quickly recover. This requires planning and different resources, such as making sure materials are readily available and staff are properly trained to respond quickly. These contingency plans are essential during major disasters to ensure that a community can face the worst.It is impossible to design for all. You might have to make some changes in order to maintain your infrastructure.Both building for the future as well as preparing for future emergencies is possible. It is possible with the right information and technology. Muench believes the bigger question is whether people will be willing to invest in infrastructure that can withstand future storms. Muench said that it was a good feeling to be able to cross that bridge, no pun intended.Many transit departments in the United States have had to deal with shrinking budgets while trying to keep a aging infrastructure together that was designed for a different climate. While future planning is vital, it often gets overlooked in favor of more immediate issues like maintaining heat-stressed roads that buckle. Crews are sent out to repair asphalt or concrete slabs and get traffic moving again. This is not a permanent solution.Muench states that it is just a matter of waiting for something to fail and then fixing it when it does. It is better to be ahead of the curve than you are now and look forward to what's next.