For many drivers of passenger vehicles, passing a semi truck and trailer is something they would really rather not do. It can be a frightening experience in the smaller vehicles.
The dreaded feeling of being sucked under that behemoth and knowing you will surely die.
The air displacement made by the semi truck and trailer begins at the nose of the truck as it cuts through the air.
Air currents run the length of the truck tractor then begin to meet the air being displaced from under the belly of the beast. This causes a vortex of air to spin, or swirl, outwards. The turbulence can make you feel like you are being sucked in, when it actually is pushing you out.
The continued forward movement of the semi truck and trailer create a tunneling vortex as it moves along the road. That is why you feel the rock and roll as you pass.
Just get a good hold on your steering wheel, stay straight. DON’T fight the buffeting. Give your vehicle a little gas and keep moving. You will be fine.
Semi truck and trailer combinations get about 6 miles per gallon of diesel fuel. In an effort to gain better fuel mileage many companies have implemented features on the trailers to streamline the air currents.
The feature most used by larger trucking companies is to attach a “skirt” to the trailer.
The air turbulence you would experience will be less terrifying when passing a semi truck and trailer with this feature.
Fuel economizing features don’t stop there. The back end of trailers have a higher rate of air turbulence as all of the vortices meet. One thing you will see is the tail “Wing” on some trailers.
These features added to trailers have raised fuel economy from 6 miles to the gallon to about 8. Some companies report fuel economy numbers as high as 10 miles per gallon and that is really great fuel mileage.
Be safe as you drive and be courteous to all others on the road. Passenger and heavy vehicles alike.