Study suggests that stiffer roads would improve trucks’ mileage

Everyone knows that walking on soft sand is more difficult than walking on a hard sidewalk. By that same token, MIT scientists are now suggesting that if road surfaces were to be made stiffer, large trucks would use less fuel.

Asphalt may not seem particularly soft to us as we walk on it, but that’s only because we don’t weigh several thousand pounds. The heavy weight of a transport truck, on the other hand, causes the asphalt to deflect downwards slightly beneath each wheel.

As a result, the truck is perpetually in a state of trying to climb out of an ever-so-slight depression in the road. This means that it burns more fuel than it would otherwise, producing more carbon dioxide emissions in the process. According to MIT researchers Hessam Azarijafari, Jeremy Gregory and Randolph Kirchain, this problem could be alleviated if roads were made of stiffer materials.

These could include traditional asphalt, to which a small amount of relatively inexpensive synthetic fibers or carbon nanotubes were added – about 10 percent of the total mix would reportedly make a big difference. An alternative would be to use a larger grade of aggregate when mixing the asphalt, resulting in a finished product made up of more rock and less binder.

Yet another approach would involve simply making roads out of concrete instead of asphalt. Although this would initially be more expensive, the roads would last longer, meaning that costs would be reduced in the long run.

Based on the scientists’ calculations, if 10 percent of US road surfaces were annually made stiffer over the next 50 years, a total of 440 megatons of carbon dioxide-equivalent emissions would be avoided. Although that represents just 0.5 percent of total transportation-related emissions for the period, it’s still a significant figure.

That said, the researchers do admit that even though the stiffer roads would likely require fewer repairs than today’s “soft” roads, the upfront changes in the construction process might initially make them more expensive.

A paper on the study was recently published in the journal Transportation Research Record.

Source: MIT

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