- All drivers are familiar with the basic traffic signal dilemma: whether to enter the intersection or to stop when they see the green phase ending. Wrong decisions to cross may lead to red light running (RLR) violations and to angle crashes; unnecessary stop decisions lead to excess queue and frustration and may lead to rear-end crashes. This study examined a conceptual in-vehicle system designed to facilitate the decision making of drivers approaching a signal. According to the distance from the traffic light and the remaining time for the green phase, the system provided an auditory and visual indication to drivers if they needed to stop. A driving simulator experiment was conducted with 20 participants; each participant drove through 28 interurban traffic lights, 14 with and 14 without the evaluated system. RESULTS showed a 96% reduction in RLR violations and a 70% reduction in the behavioral dilemma zone range. Change in signal crossing decision probability was modest (6% reduction) and not statistically significant. An exploratory evaluation suggested that driver hesitation during the amber light was substantially reduced and that intersection clearing time was shorter and much more predictable. If similar effects occur in reality, fewer angle crashes and fewer rear-end crashes can be expected.