The application of a design vehicle as an integral part of highway geometric was formally establish by AASHO in 1940. This early AASHO documentation contained a set of four design vehicles, generally the largest in each category including an automobile, bus and two trucks. Swept paths for simple 90 degree turns for the single wheelbase vehicles were developed based on equations.
The 1954 AASHO “A Policy on Geometric Design of Rural Highways”, was published and Mr. Jack Leisch, shortly thereafter developed the first set of plastic turning vehicle templates at a scale of 1”=50’, 1”=40’ and 1”=20’ for the use of DeLeuw Cather staff and a limited number of others. Jack Leisch moved to Toronto, Canada in 1964 and CGRA under Mr. Leisch’s direction, developed the second generation of turning vehicle templates which were sold by CGRA throughout Canada and the US beginning in 1969.
These plastic turning templates and their future generations became the standard approach to the
design of any vehicle facility and is still used widely today. The development of the computer led to several developments on mainframe computers that allowed the simulation of turning vehicles, however it wasn’t until the early 1990s, with the dawn of the microcomputer that programs such as AutoTRACK, AutoPATH, and AutoTURN®, that operated directly within CAD, became a popular approach to designing for turning vehicles at intersections, roundabouts, parking facilities truck terminals and bus stations. These approaches provided designers with considerable flexibility and efficiency in a CAD environment over fixed plastic (mylar) turning templates.
One future direction is for design to be fully inclusive of vehicles turning requirements, such that it
allows for a highly dynamic and integrated approach, eliminating the need to check for the required
space after the fact. Coupled with expert systems capabilities, these programs will provide powerful
and highly effective methods for providing for the spatial requirements for design vehicles, in all
dimensions – horizontal and vertical, as well as speed.
This paper will chronicle the evolution of the application of design vehicles in geometric design from
inception in the late 1930’s to the present and provided insight into the future of this fundamental
component of road and facility planning and design.
