Stiffer Roads = Less Fuel, Engineers Say
Announcement posted by DesignBuild Source 25 May 2012
Ever found walking on sand harder than walking on a footpath?
If so, there is a reason, engineers at the Massachusetts Institute of Technology say.
With each step, your foot tamps down the sand from heel to toe, requiring you to expend more energy than when walking on a hard surface. In other words, walking on a soft surface takes more energy than walking on a hard one.
The same effect occurs when driving, according to a new study released by MIT professor Franz-Josef Ulm and PhD student Mehdi Akbarian. Unlike other studies, which focus on roadway experiments, Ulm and Akbarian’s study was the first to use mathematical modelling to look at the effects of pavement deflection on vehicle consumption across the US. Recently, their study was released in a peer-review report. A paper on the work has been accepted for publication later this year in the Transportation Research Record.
By modelling the physical forces at work when a rubber tyre rolls over pavement, Ulm and Akbarian conclude that because of the way energy is dissipated, the maximum deflection of the load is behind the path of travel. The upshot is this: tyres are forced to drive continuously up a slight slope, making the car work harder to travel a given distance, thus increasing fuel consumption...