TRIPLE TRAILER EVALUATION IN UTAH

An evaluation was made of the operation of triple trailer combinations in comparison with doubles and singles during a one year field study in Utah. The evaluation included safety, operating costs, pavement effects, and human factors associated with triples under actual on-line operations as related to the other combinations. The results showed that triples do reduce operating costs and they do conserve fuel. They do shorten pavement life in comparison with single trailers but no more than doubles. The accident data are limited due to the number of miles traveled during the year but it does indicate that triples are safe under the conditions in which they were operated. Questionnaires were completed by truck drivers and the traveling public and the results are summarized in the report. The traveling public became more favorable with time and the truck drivers became less favorable. Braking tests, offtracking, vehicle swerving, effects of road and weather conditions, and passing time were also evaluated. Portions of this document are not fully legible.