The Surface Transportation Assistance Act (STAA) of 1982 mandated the operation of large trucks (generally 102 in. wide and 41 ft from kingpin to rear axle) and twin tractor-trailer combinations on most Interstates and many primary highways, and in 1987 the Surface Transportation and Uniform Relocation Assistance Act reinforced the trend. Many states have rapidly expanded the highway system for longer vehicles by adding secondary highways, many of which involve urban streets and intersections. Many of the intersections are substandard if compared with the ideal 62-ft wheelbase turning template. However, truck operators and automobile drivers take compensatory measures that allow the longest vehicles to successfully negotiate most of these marginal geometric configurations. Demonstrably, full-scale improvements are unnecessary in many instances in which street widths meet or exceed certain minimum tolerances. However, when intersections are so seriously deficient that the operation of long trucks through them endangers public safety, a rational way to identify them should be available to engineers, local officials, and other decision makers. A methodology is presented that allows decision makers to rationalise this process and defend their judgement.
Abstract