Semi-Truck Information

by Rob Wagner
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Elvis Payne, cauchi_a, jacksnell, Diane S. Murphy:

Semi trucks haul an estimated 70 percent of all goods in the United States today, far outstripping rail freighters, ships and aircraft. Also identified as tractor-trailer rigs or semi-trailer trucks, the value of goods transported by these vehicles exceeds $255 billion, with an estimated 1.9 million semis plying the highways. It was only through government-funded paved highway construction projects that the semi became the leader in freight transportation.

Semi Truck Defined

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The semi truck is an 18-wheeled articulated truck featuring the truck, consisting of the engine and cab, and trailer. These semi big rigs are equipped with three axles. The front axle steers the vehicle, while the rear-wheel-drive axle propels it. Double wheels, or dualies, give the vehicle stability and traction, according to

Early History

Only 700 large trucks were on the road in 1904, with that number leaping in 1914 to 25,000 and then a whopping 416,569 by 1924, according to Big rigs were utilitarian and not designed for comfort.


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Technology limited the use of big trucks before 1925. Trucks generally featured an open cab with no doors and little protection from the elements, according to Hydraulic brakes were not yet a feature and trucks' stopping power came from primitive mechanical brakes. Solid rubber tires limited the semi to short distances, usually in urban areas.

Pioneering Peterbilt

A leading semi today is Peterbilt, founded as an answer to transport lumber from the Northwest forests to lumber mills. Lumber tycoon T.A. Peterman developed a heavy-duty truck in 1938 by building custom truck chassis using equipped he purchased from the bankrupted Oakland-based Fageol Motors, according to The Peterbilt gave birth to the modern semi.

Truck Culture Emerges

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The Federal Aid Road Act was passed in 1916. In 1921, the Federal Highway Act was passed that allowed for the construction of 3.2 million miles of roads throughout the U.S. The Federal-Aid Highway Act, signed by President Dwight D. Eisenhower in 1956 and the North American Free Trade Agreement passed by Congress in 1994 cemented the semi's dominance on U.S. highways, according to and the National Transportation Administration.


Sleeper cabs began to appear on semi rigs in the 1940s with Autocar and other makers developing what today is considered an extended cab that allows just enough room for the driver to take a nap in the rear of the cab. The sleeper has developed over the decades to reach in size today to 70 inches long to accommodate husband and wife driving teams and equipped with the comforts of a small studio apartment, and


Federal laws enacted since the mid-1970s have significantly reduced semi truck accidents. Only about 4 percent of accidents involving semis are due to driver fatigue. GPS technology, in-cab computer access and satellite communication systems installed in semis keep truckers in constant touch with dispatch centers, according to

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