“Full monty” or low-key:Two traffic management approaches and their effect on change perception

European road authorities differ in their views on whether variable-message signs (VMSs) can be in use continually or that they should only display information when necessary. This study compared the two approaches in terms of the ease with which drivers perceive changes in traffic management information on VMSs. In a 2x3 design, change detection for variable speed limits on VMSs was measured for information addition and information change under three conditions of information discriminability. Participants were shown videos of a single motorway – in order to create a more natural setting in which they are familiar with the road – while using an intentional approach in which participants were aware that something could change. The preliminary results are discussed in relation to detectability of, recollection of, and expectations about the new speed limit. This research gives more insight into change detection failure for the two traffic management approaches and possible countermeasures