Can trees save our streets?

It’s been a rough year for Michigan roads. Declining funding and tumultuous weather have taken its toll on our streets. New potholes form just as old ones are being patched. While the condition and improvement of Michigan’s roads is a complex problem, trees may provide some of the answer.

Asphalt is comprised of an aggregate and a binder. The aggregate creates the “bulk” of the pavement whereas the binder helps hold everything together. In the summer, roads get hot. Very hot. Temperatures on pavement surfaces can reach 130 degrees on hot, sunny, summer days. These hot temperatures can accelerate the break-down and evaporation of the binder causing the street to harden and become more brittle. Over time, this can make it easier for cracks to form.

A United States Forest Service study in Modesto, California wanted to determine whether or not the shade provided by trees might help slow the process of pavement break-down. The researchers theorized that shade would help cool the pavement and might have implications on how quickly the binding agent might evaporate.

However, this research was performed in California. Considering climatic differences, the results may not fully extrapolate to our cold, snowy Michigan winters. That said, the research that has been performed to date has identified an important link between tree shading and street quality. While California may seem worlds away, this analysis points to existing data that can be used to discuss the important beneficial relationships between trees, shade, and our roads.


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