Judgements of local council traffic engineers on necessity for traffic sign installations

Seventy three traffic engineers were shown a film containing 27 traffic sign installations. These persons made judgements of whether the sign was required at that particular location, along with comments about how the installation might be changed or improved. Respondents were, for most sites, inconsistent in their responses; that is, for any given site, respondents were not in agreement as to the need for a sign. In addition, there appeared to be bias in many individual respondents in that they tended to nearly always respond yes or no for all signs presented. A detailed analysis of these responses showed that ilr (indicated level of response, being a measure of perceived necessity for the sign) was not significantly correlated with rsi (reported level of sign information - as used by macdonald and hoffman, 1984) or any other factor related to the sign installation (such as sign redundancy) (a).