Efficacy of dynamic traffic management measures: the influence of complexity and situational awareness

Behavior of road users (e.g. route choice, driving behavior) is a critical factor in the efficacy of measures applied in the context of Dynamic Traffic Management (DTM). In order for drivers to make well-informed decisions, it is required that information provided by DTM measures is perceived. In this regard, situational awareness is a psychological construct of high importance. Situational awareness is defined as the perception of elements in the environment within a volume of time and space, the comprehension of their meaning and the projection of their status in the near future. With regard to the relationship between situational awareness and the efficacy of DTM measures three aspects are relevant: spatial awareness, system awareness and task awareness. A driving simulator study was performed to analyze to what extent complex interaction with other traffic and the complexity of DTM measures influence spatial awareness and system awareness. The complexity of interactions with traffic was simulated by the induction of speed changes of the lead vehicles. Whereas the complexity of DTM measures was induced by exposing participants to maximum speed limit signs and route information with an increasing level of complexity and ambiguity. Spatial awareness and system awareness were measured through eye fixations using a new data collection and analysis technique. Furthermore, a psycho-spacing car following model was estimated to measure spatial awareness, while the compliance to the DTM measures was considered another measure for system awareness. The influence of complex interactions with other traffic as well as of the complexity of DTM measures was analyzed through Multivariate Analyses of Variance.