In 2006 aerodynamic devices had not penetrated the trailer market much at all. What a difference a decade makes. During July, I spent a few weeks working at a few companies in Colorado - one week spent at Rocky Mountain Institute a partner in our trucking efficiency work. My wife and I decided to drive the 2,200-mile roundtrip on I70 from Indianapolis to Denver. So, what did we do on that long lonely highway to pass the time? Of course we did, we counted the aerodynamics devices on 5,000 tractor trailers. And what we found even surprised me.
We looked for trailer skirts, wheel covers on tractors and trailers, drive tandem fairings on the tractors, rear fairings and underbody devices on trailers. Rear fairings consisted of foldable tails, a top kick system and even a few air tabs. What we found follows:
- 3,115 of the tractor trailers, or 62%, had at least one of these devices.
- The most common was side skirts, on 2,711.
- Wheel covers on 463.
- Drive tandem fairings, the newest of these technologies, were on 78 tractors.
- Underbody devices on 218.
- One of the Rear fairings on 317.
- We found 80 trailers with three of these systems and 32 with four.
Now, granted, this route on I70 is on a major highway and in the middle of the United States, so it is likely that there are more aerodynamic devices on this route, likely making these numbers higher than the national average. But it is clear that fleets are finding value in these devices and using them on their trailers. So we are making progress. And in addition to the fuel saving benefits of trailer aerodynamic devices, we found fleets that invest in them get added stability along with reduced splash and spray and less driver fatigue.
In NACFE’s trailer aerodynamics confidence report published earlier this year, we summarized that about 40 percent of all new trailers are equipped with some sort of aerodynamic device, the most popular being trailer skirts. In addition, one quarter of the trailers on the road have at least one aerodynamic device. Of course most of this movement has been in the van trailer market which accounts for 66 percent of the trailers on the road.
The thing with trailer aero is that even small things can provide measureable results. Things like vented mud flaps that are matched to the width of the tire, relocating license plate, removing items on the trailers that add drag and lightweighting result in accumulated savings over time.
Figuring out the actual benefit you’ll get from an aerodynamic device can be a little tricky, however. Things like temperature, prevailing winds, weather, traffic, fuel differences make it hard to directly correlate savings realized in test runs from what a fleet actually gets. But that should not stop you from making the investment in these devices. Your results could, in fact, be better than the test results.
We’ve come a long way in the past 10 years when it comes to improving aerodynamics on trailers. I am excited to see how trailers will be outfitted 10 years from now and what types of savings we’ll be seeing from aerodynamic devices for all types of trailer configurations. We even saw a few bulk and flatbed trailers with skirts and wheel covers, even though we weren’t counting them!