life in the slow lane

As I write this, diesel fuel costs here in the Northeast have passed the $4-a-gallon mark. The federal Energy Department expects that those will come down some, but it still forecasts that prices nationwide will average $3.73 a gallon this summer.

Those high prices, along with growing attention to the effect of carbon emissions on the environment and general agreement that the nation has to reduce its reliance on petroleum imports, add up to a greater focus on ways to cut back on the amount of petroleum products we consume.

The suggested fixes are plentiful; some are complex, some on the technological cutting edge, some as simple as checking to ensure tires are properly inflated. What has not seemed to receive a lot of attention is a very simple step that could cut over-the-road fuel use by millions of gallons and carbon emissions by hundreds of millions of pounds.

Slow down.

That's it. During a recent lunch meeting with Randy Mullett, director of government relations for Con-way Inc., about the corporation's sustainability initiatives, he suggested that a nationwide effort to simply enforce existing speed limits would have those significant effects. Wow. It's elegant. It's simple. It could start today. It doesn't mean a return to the 55 mph limit that Congress adopted following the 1973 fuel crisis. It means simply following current law and perhaps providing states with additional funds to enforce the speed limits.

I'm not sure what the total potential savings would be in fuel costs and emissions if both trucks and cars began to obey the speed limits in large numbers, but it would be substantial.

Truck builders and motor carriers know for a certainty what it can mean for them. For example, Con-way Freight, Con-way's less-than-truckload subsidiary, recently scaled back the speed governors in its 8,400 tractors to 62 miles per hour from 65 mph. "The move is expected to reduce consumption of diesel fuel from its over-the-road tractor fleet by nearly 3.2 million gallons annually while eliminating approximately 72 million pounds of carbon emissions from the environment," the company said in announcing the change.

According to a 2006 white paper published by Kenworth, a major truck OEM, improving heavy truck mileage by as little as half a mile per gallon for a tractor that travels 100,000 miles a year could reduce fuel consumption by between 6.3 and 9.1 percent, depending on the vehicle's current efficiency. Thus, at 5 miles per gallon, 100,000 miles, and $3 a gallon (this was back in 2006, remember), fuel would cost $60,000. Improve to 5.5 mpg, and the cost falls to $54,543. Kenworth says that as a general rule of thumb, every mile per hour over 50 reduces fuel efficiency by about a tenth of a mile per gallon.

Certainly, a large number of factors affect truck fuel mileage. But, the paper says, "Excessive speed is the biggest single factor in reduced fuel mileage." Slow down, and the savings mount. And emissions fall. And demand for imported petroleum softens ever so slightly.

Now, I'm not naïve enough to believe that even a widespread public campaign could easily or quickly affect driver behavior. Gas at $3 a gallon certainly hasn't, based on what I see on the roads. (And I admit that I can have a lead foot on the pedal myself.) But truckers and their customers are in a position to make a change that would reduce costs, reduce fuel consumption, reduce emissions. And on a 1,500-mile lane, all other things being equal, averaging 62 mph rather than 65 costs a mere hour in transit time.

If we're going to get serious about addressing the linked issues of petroleum imports and carbon emissions, that seems a good place to start.