A commercial tractor-trailer is often called a “semi truck” or simply “semi” the origin of the term came from the recognition that the trailer had no front wheels and was unable to move itself. Hence, the semi trailer tag stuck and from that came the term “semi truck”.
A typical trailer is about 53 feet long and may have breaks that automatically engage when the trailer is not attached to a truck. Attaching the trailer to the tractor releases the brakes so the articulated vehicle can move.
There are over 3 million licensed commercial truck drivers the United States. Nine out of 10 trucking companies in the United States are what is called – owner operators.
Big rigs travel over 100,000,000,000 miles a year and deliver the majority of America’s goods. Our infrastructure and our economy is dependent upon commercial vehicles.
Big trucks log many miles every year. Estimates vary, it is not unusual for a commercial truck driver who does long-haul drives to exceed 100,000 miles a year.
Estimates place the MPG of big rigs at about 6 to 7 miles per gallon. However, recent changes in fuel economy standards should serve to increase the mileage of big rigs and have an impact on our consumption of diesel fuel.
Big rigs can weigh up to 80,000 pounds in America. Other countries have different standards for big rigs and some countries allow multiple trailers connected to one tractor, making a very long vehicle for maximum efficiency.
The most popular tractor in America is the Freightliner followed by Navistar international. The Mack truck is fourth in popularity and is manufactured by Volvo.
A tractor-trailer takes approximately 1/3 longer to stop at highway speeds than a typical passenger car or pickup truck. With the difficulty of articulated vehicles to stop, many truck wrecks occur due to improper braking or a jackknife after a brake application.