Self-explaining roads : an exploratory study.

The short version of this study was presented at the conference `Road Safety in Europe and Strategic Highway Research Program (SHRP)', Lille, France, September 26-28, 1994. See also IRRD 859169 and for the abstract IRRD 882436: The design of many roads and their typical appearance reflects the way these roads developed through history. Because the road design is not considered as a system property optimally adapted to the human capabilities, there is by no means a structurally safe traffic system. The crucial question is how potential errors occurring in traffic can be reduced by revising the lay-out of the road environment. The so-called Self-Explaining Road (SER) is a traffic environment which is in line with the expectations of the road users. Expectations emerge because road users develop prototypical representations of different road environments. In order to determine the prototypical representations underlying road categorization, subjects had to categorize pictures of road environments as fast as possible. The underlying notion is that a road which looks very much like the prototype stored in memory can be quickly categorized, while a road unlike the prototype will take longer to categorize. Pictures were taken from existing roads outside the built-up area. Particular road elements within these environments were systematically taken out of or inserted into the picture. The response pattern indicated that road users do have a strong prototypical representation of a motorway. There appears to be no prototype of a 4-lane 80 km/h road for fast traffic. The results indicate that the emergency lane in combination with other road elements on a motorway can be used to discriminate between a motorway and a 4-lane 80 km/h through road for fast traffic. In addition, direction lane on a 4-lane 80 km/h through road for fast traffic helps to discriminate between a 4-lane 80 km/hthrough road for fast traffic and a motorway. The presence of city-like elements like parked cars, houses, alleys helps to discriminate between a 2-lane 80 km/h road for all traffic and a 80 km/h 4-lane road for fast traffic. (A). (For a fuller report, published in Dutch in 1992, see C 1332 (IRRD 859169).