The IN-SAFETY (Infrastructure and Safety) Project focuses on the pre-requisites of a successful implementation of Intelligent Transport Systems (ITS) in order to enhance the self-explanatory nature of roads. The European driver has to cope with more and more complex traffic environments, including vertical and horizontal signing;​ frequently supported by telematics.

Due to the complexity of road information there is a strong need to support the driver with homogenized pictorial messages. The readability and understandability of pictorial messages on a VMS (Variable Message Sign) was analyzed by evaluation criteria and methods of ISO 9186 “Test methods for judged comprehensibility and for comprehension“. This paper discusses as well the evaluation and the results of the Comprehensibility Judgement Test, done in Austria, Hungary, and Czech Republic and Spain. For 33 referents a total of 243 variants were tested. In total, 825 voluntary drivers participated in the study. 28 referents reached a median value of judged comprehensibility exceeding 85. In 104 cases thresholds for immediate acceptance have been exceeded. Among them 56 variants were proposed for a redesign in order to enhance chances for positive results when applying the following Comprehension Test.