Semitrailers. You see them everywhere. At your local Jewel. At Walmart. At the Kraft Distribution Center. On the toll road going into and out of Chicago. On the highways in the countryside. How many can there be? Hundreds? Thousands? More than that?

According to, “there are 5.6 million semitrailers (or tractor trailers) in the U.S. That is almost three times the number of semi trucks (also called tractors). Since a trailer has no front wheels and can be used only when connected to the tractor part of the truck, it is called a semi-trailer.”

The article continues, “Trailers are typically 53 feet long. They have brakes that are automatically applied when the trailer is standing unattached to the truck. When the truck is connected to the trailer, pressure from the truck’s engine-powered air pump releases the brakes so that it can roll.”

How important are semitrailers to our way of life? According to the article, semitrailers deliver sixty-eight percent of all goods in the U.S. Amazon has announced the purchase of thousands of semitrailers to send items around the country and to get orders to customers faster. The United States Postal Service uses semitrailers to transport mail from one processing facility to another or to stations and branches. Semitrailers deliver new cars from the factory to the new car dealers lots.

According to the Popular Mechanics article, there are 3.2 million truck drivers in the U.S. You are probably familiar with the names of some of the biggest companies including United Parcel Service, Fed Ex, J.B. Hunt, and Schneider. However, about 90 percent of trucking companies and owner-operators have fewer than six trucks. Each year a single semi will average 45,000 miles. Long distance trucks average 100,000 miles per year.

Many of the routes are on interstate highways built to carry the weight of a fully loaded semitrailer. The maximum weight allowed for a semitrailer is 80,000 pounds spread over eighteen conventional wheels. Problems sometimes occur when a semitrailer has to travel on two lane highways with bridges not built to handle that weight. In that case, the driver has to reduce the weight of the load before traveling such roads. State police set up weigh stations on highways to ensure that trucks are in compliance. If a truck exceeds the maximum weight allowed, the trucking company can receive a hefty fine.

If you are going to be sharing roads with semitrailers, you need to be aware of the fact that semitrailers have certain blind spots. That means the truck driver cannot see your vehicle at certain times. The Queensland (Australia) Government—Department of Transport and Main Roads published the following information at

  1. Stay out of the heavy vehicle blind spots.
    • Immediately in front of the truck
    • Beside the truck driver’s door
    • On the passenger side which runs the length of the truck
    • Directly behind the truck
      Remember: If you can’t see the truck driver’s mirror, the truck driver cannot see you.
  2. Travel at a safe following distance.
    • Do not follow a heavy vehicle too closely. Allow time to stop safely.
  3. Look out for turning heavy vehicles.
    • Trucks need more space when turning. Trucks may take up more than one lane to turn at corners, intersections, and roundabouts.
  4. Overtaking safely around heavy vehicles
    • If traveling on the motorway/highway, try to use overtaking lanes whenever possible.
    • Only overtake when the road ahead is clear.
    • Be aware of strong wind conditions as you pass a vehicle.
    • When it is safe to pass, indicate, accelerate and pass quickly, without exceeding the speed limit.
    • After passing, maintain your speed so the heavy vehicle does not need to brake.
    • Never attempt to pass a heavy vehicle or other long heavy vehicle on a curve or hill as your visibility is reduced.

—By Karen Centowski

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