Gantries or Cantilevers for Route Guidance on a Reorganized Arterial Road? A Before Study of Route Choice Effectiveness Using a Traffic Sign Simulator (Case Study)

AbstractThis study evaluates ex-ante which of two signalization concepts is most effective at a reorganized arterial road in Hasselt (Flanders; Belgium): a gantry (advance direction sign above the road) or a cantilever (advance direction sign alongside the road). Over a distance of 500 meters, three intersections will be replaced by five intersections with traffic lights and the number of sorting lanes will be increased. The complexity of the situation poses a challenge as to how most optimally signalize route guidance.Twenty-two participants drove seven different routes in a medium fidelity fixed-base simulator with a mock-up in front of a single projection screen. Participants were exposed to an animated graphic road environment that integrated a full HD video recording of the actual real life road environment and a virtually developed scenery. The video contained 3D animations of the foreseen geometric road realignments. We used a within-subject design with origin, destination, and signalization concept (gantry vs. cantilever) as the manipulated conditions in a randomized order. Participants were able to control the rendering of the video simulation by means of the gas pedal, mimicking speed. The direction indicator was used to signal lane switches and route-related decisions at a number of predefined locations. In addition, we recorded eye tracking data by means of a combined FaceLab-EyeWorks system. For each drive, we instructed participants to head for one of the destinations. In the analysis, reaching the destination (outcome of a decision) was less important as the performance at a decision point (optimal or suboptimal). Performance was measured in terms of capacity gains (correct car in the correct lane) and less weaving behavior (as a surrogate of traffic safety). At the end of the experiment the participants completed a short questionnaire.Test scenarios with gantries resulted in more optimal decisions compared to scenarios with cantilevers and participants needed less attempts to reach the correct destination. Compared to the cantilevers, participants had more but equally long eye fixations on the gantries, resulting in a higher total fixation duration time for the latter. The questionnaire showed that 73% of the participants preferred the gantries over the cantilevers. Based on the simulator study gantries can be considered as more effective in terms of route guidance than cantilevers because they induce the lowest number of maneuvers. Consequently, the recommendation was to equip the reorganized arterial with gantries