Letter to the Editor: To the Swiftest

This Letter to the Editor appears in the June 1 print edition of Transport Topics. Click here to subscribe today.

To the Swiftest

I enjoyed the opinion piece titled “To the Swiftest Go the Spoilers” by Phil Romba in the May-June Equipment & Maintenance Update supplement to the May 18 issue of Transport Topics.

I wanted to continue the discussion with some additional facts related to aerodynamic certification and product offering under the California Air Resources Board and U.S. Environmental Protection Agency programs.

Romba is partly on point — CARB and EPA are not simply overstating fuel savings; they are oversimplifying the solution by certifying technologies based upon data that do not reflect operational reality.

As a result of these actions, the public and the industry are being misled, so that in the long run, these actions will cause more harm than good. At the very least, the certification label must come with supporting information — or perhaps a warning.

The industry and the citizens should be informed of the range of conditions to which the certification is applicable, including speed range, yaw range, weight range, temperature range, humidity range, road surface type, aerodynamic device setting, tire type and vehicle setup, such as tractor-to-trailer gap.

For example, the current certification process only considers data for 0 degree of yaw despite the fact that the average yaw condition in California is closer to 7 degrees.

(It should be noted that the 7-degree yaw value is based only upon weather and does not include factors that can increase yaw angle, such as the effect of traffic, route selection or vehicle speed.)

It is well known that aerodynamic devices are highly sensitive to yaw angle. A survey of devices shows that some become less effective with yaw angle, while others improve with yaw angle. Limiting certification to 0-degree yaw angle results both in overestimating and underestimating device benefits.

If the fleet buys the wrong product based upon the certification, will CARB or EPA provide a refund?

Regarding Romba’s point about average vehicle speed, the ability of an aerodynamic device to reduce fuel use varies directly with rolling resistance. As such, an 80,000-pound vehicle with conventional dual tires will receive a significantly lower benefit from a given aerodynamic device than a 60,000-pound vehicle with low rolling resistance tires.

For example, a certified 5% aerodynamic device on a vehicle with an average speed of 50 mph operating 100% of the time on an empty and level road in still air at 65 degrees Fahrenheit will reduce fuel use as little as 1% for the heavier vehicle, while providing 5% fuel savings for the lighter one.

CARB and EPA are not helping the industry or the citizens of California or the United States by oversimplifying the process. They need to step up and put all the facts on the table. 

Richard Wood


SOLUS-Solutions and Technologies

Virginia Beach, Va.


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