Efforts in the 1970’s to require that US. heavy vehicles be equipped with antilock braking systems (ABS) were unsuccessful, in part, because of truck user concerns about the in-service operational reliability and serviceability of the systems. As a necessary pre-step to reconsidering a requirement for ABS, the National Highway Traffic Safety Administration began, in 1988, a large in-service field evaluation of current-generation ABS systems in order to determine if they would function reliably in U.S. trucking operations. Reliability and serviceability has been tracked on 200 ABS-equipped truck tractors, operated by seventeen fleets in six U.S. cities for a two year period beginning in late 1988/early 1989. Beginning in late 1990, 50 ABS-equipped trailers of objective test procedures are available which are basically applicable to heavy commercial vehicles as well. In doing so it has to be considered that there is a need for adapting either the initial driving conditions or the criteria of evaluation accordingly.

With regard to the variety of commercial vehicle configurations it will be necessary in some cases to confine to comparative tests in order to evaluate basic conceptions and the effects of special parameters respectively. As illustrated by the example of different loading conditions then these test procedures form expressive facilities to assess the handling and braking characteristics of commercial vehicles. Consequently it seems necessary and useful to continue with the work in applying these test procedures to adapt vehicle technology to the human capabilities for a further improvement in traffic safety.