Analysis of Speed Disturbances in Empirical Single Vehicle Probe Data before Traffic Breakdown

In single vehicle probe data measured on German freeways we have revealed phase transitions from free flow to synchronized flow and back to free flow that occur before traffic breakdown at a bottleneck occurs. Thus resulting in the formation of a congested pattern. Empirical findings of these phase transitions confirm a microscopic stochastic theory of traffic breakdown developed by Kerner. Only because of the recently introduced possibility of gathering larger amounts of anonymized vehicle data – including a sequence of positions of each car – we were able to show the phenomenon of these phase transitions in measured floating car data. This contribution reveals empirical findings in microscopic data which support and prove some of the recent theoretical findings of the nature of traffic breakdown.