This study investigated to what extent cognitive road classification determines driving speed. Both a picture sorting and a driving simulator task were used to investigate the effects of design characteristics on cognitive road classification and driving behaviour. In both tasks, three road design conditions were involved: (1) one consisted of a set of Current Roads (CRs), roads as they are in reality; (2) one of a set of `Self-Explaining' Roads (SERs); and (3) one of both CRs and SERs. Each of the three different road sets consisted of eight exemplars of each of four road categories: (a) motorways; (b) 100 km/h roads; (c) 80 km/h roads for fast traffic; and (d) 80 km/h roads for mixed traffic. The picture sorting task showed that subjects categorized SERs more in accordance with the official road category system than CRs. A more selective and systematic application of road characteristics to road types, caused a classification that was more in accordance with the official road category system. Subjects did not only classify on the basis of road characteristics, but also used the whole set of road environments they were part of. The driving simulator task showed that driving behaviour on motorways with a SER design was more in accordance with driving behaviour as meant by the official road design. No clear-cut evidence was found for an effect of cognitive road classification as such on level of driving speed. Yet, results showed that more consistent road design within categories may cause more homogenous driving speeds.
Abstract