Method for traffic management applications on freeways based on the probability of breakdown

Capacity is one of the relevant values to describe traffic flow on freeway segments. It depends on various conditions such as roadway, traffic, environment and control conditions. The magnitudes of the influencing values on capacity, that are described in guidelines, are mostly based on just a few research studies with little spatial and temporal data sources. In the past, capacity was defined as a deterministic value for given base conditions. Newer research studies, however, prove that capacity has to be interpreted as a stochastically distributed value. The more the traffic flow increases the higher the risk of traffic breakdowns. Aim of the current study is to derive statements on how capacity is influenced by various conditions based on a probabilistic description of capacity. The model developed for this purpose shall be applicable without any sophisticated calibration. An algorithm is developed which is able to anticipate traffic breakdowns and this way allows a preventive control of the traffic flow.