Thanks for your comments. The on-line Trucking Decision Aid concept applies primarily to independent truckers (that own their vehicles), or the dispatchers of trucking firms with a small fleet, and only if there is time flexibility (e.g., a 12 to 24 hour window within which a load must be delivered). The planning decisions are when to depart, whether to accept a load and how to much to charge. Roughly, for a semi tractor-trailer traveling at legal highway speed (e.g., 65 mph), if the headwind speed, in line with the road, is 20 mph (85 mph relative wind speed), the fuel consumption per mile roughly doubles. If the relative wind to the moving truck is 15-degrees off-axis, the coefficient-of-drag roughly doubles from the in-line case. I've spoken to some independent truckers at truck stops in the United States. They may not know the engineering calculations, but, from their on-road experience, they know what a 20 mph headwind can do to their bottom line (cost of diesel fuel). One trucker came up to buy a cup of coffee as he paid for the cost to refuel his big rig, and threw his hat down on the counter with, "Not going to make anything today. Bucked strong headwinds all the way." Trucking operations do have some time flexibility. A close cousin to strong head winds is hazardous weather. For example, if a large portion of the highway is covered by glaze ice that is forecast to melt 8 hours later, what would the trucker decide to do? If he has to feed his family, he may decide to take the increased risk and leave early, which brings in highway safety.