The United States is Now Criss-Crossed by Nearly Four Million Miles of Roadways

4 Aug

And what we need more trees, less highways.

Photo by flickr user shawnconna

I found this article the other day when browsing the site of the very excellent organization Friends of the Pittsburgh Urban Forest and thought it was worth sharing. Notice especially the part in italics:

Why Shade Trees? The Unexpected Benefit

Davis, CA (November 1, 2007)- We would all prefer to walk down a tree-lined street to one without trees, but did you know that the street itself prefers to run under trees? This report examines the cost-saving benefits of having shaded streets. All other factors equal, the condition of pavement on tree-shaded streets is better than on unshaded streets. In fact, shaded roads require significantly less maintenance and can save up to 60% of repaving costs over 30 years.

After more than 100 years of road and highway building, the United States is now criss-crossed by nearly four million miles of roadways. Add in all the parking lots, private roads, driveways, and road shoulders, and the total amount of paved land comes to approximately one percent of the total area of the contiguous United States. The cost of maintaining this asphalt can be lowered through urban tree planting.

Photo by flickr user scratch n sniff

Asphalt streets are a combination of filler materials, known as aggregate, and a binder- asphalt cement- on top of one or more layers of gravel and compacted soil. As pavement temperatures rise, the binder evaporates and breaks down and the pavement begins to harden, making it easier for cracks to form. Tree planting along roads provides shade, thereby improving pavement conditions. According to research conducted by this study, 20% shade on a street improves pavement condition by 11%, which is a 60% savings for resurfacing over 30 years. Read Tips for Street Shading Trees

Three Easy Things You Can Do

1. Learn to identify the trees in your neighborhood

2. Become a tree tender at your local urban forestry or tree organization

3. Write to your local legislators to voice support to fund tree planting programs

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