US national speed limits should revert back to 55mph. This change is a highly effective method for increasing the efficiency of all cars on the road while costing very little to implement. Developing automobile technology may eventually help rid us of our compelling need for oil however; lowering speed limits can have a dramatic impact on fuel savings immediately.
Physics dictates that slower moving vehicles will carry less force on impact during a crash. Less impact force means less energy that vehicles will need to dissipate or redirect to keep occupants safe. However the proportion of safety we gain is not directly related to our highway speed limits. In Europe for example, highway speeds average much higher than in the US, yet percentage wise, they are safer drivers. Numerous factors contribute to this statistic though as the roads, cars, and licensing requirements are each drastically different from the United States.
As speed increases so must the amount of power to overcome the increased resistance. This is not a linear relationship however. The average car needs roughly 65% more power to drive at 65 mph rather than 55 mph[i]. As the speed difference increases, the power required shoots through the roof. In the scenario above, the car needs approximately 105% more power to travel at 70 mph rather than 55 mph. This shows that it takes less than half as much power to drive your car at 55 mph vice 70 mph.
LOW IMPLEMENTATION COST
The real beauty of changing our national speed limits is that it is a quick and almost cost free initiative. For the price of a robust advertising campaign, and replacing several thousand road signs, this program can be implemented. The return on investment will begin occurring almost immediately as both highly efficient automobiles and gas guzzlers alike can all save due to the physics of decreased resistance.
New vehicle efficiency research will continue to help us develop more cost effective transportation but even those technological wonders will benefit from the reduced speed limits. Diesel, gasoline electric hybrids, even fuel cell vehicles will all enjoy even higher efficiencies than are currently projected. This is in addition to the reduced environmental impact of consuming so much less energy!
MINIMAL TIME COST
Lowering the national speed limit does not come without a cost however. Reduced speeds will increase travel time. Slowing from 65 mph to 55 mph will take roughly 36 minutes longer on the 215 mile transit from Boston to New York for example. As fuel prices keep rising however, the time savings of driving at higher speeds come at a higher and higher cost. While there is a value to be placed on our time, given sky rocking fuel prices, you have to ask yourself, how much is my 36 minutes worth?
Reducing our nation’s highway speeds not only keeps more money in consumer’s pockets, but also marginally increases highway safety while reducing our oil decency. The speed limit reduction program will therefore cost very little to implement, yet save consumers money, reduce environmental impacts, and oil decency all for the relatively low cost of a little extra travel time.