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Vehicle offtracking models

In: Transportation Research Record, No. 1052, 1986, p. 53-62

Authors: Michael W. Sayers

When a vehicle turns, the rear wheels track inside the path traced by the front wheels. This behavior is called offtracking and can lead to problems when large trucks operate in confined areas. The methods that have been used by designers to estimate the offtracking of heavy trucks are reviewed, and then a computer method for graphing the complete swept path of an arbitrary vehicle making any type of turn at low speed is described. The method is valid for nearly all truck configurations in use on the highways, including double and triple combinations. The paper includes several example plots, and a computer program that uses this method, developed for the Apple II computer, is described. The program is available free from the Federal Highway Administration.