Speed-Density Relationship: from Deterministic to Stochastic (Paper # 09-1527)

Traffic flow is a many-car system with complex and stochastic movement. It is difficult to describe the system dynamics solely using deterministic models which describe average sys- tem behaviors. Therefore, a stochastic speed-density relationship is proposed as a further step forward to overcome the well-known drawbacks of deterministic models. Modeling results show that by taking care of second-order statistics (i.e., mean and variance) a stochastic speed- density model is suitable for describing the observed phenomenon as well as matching the empirical data. From here, a stochastic fundamental diagram of traffic flow can be established. The stochastic speed-density relationship model can potentially be used for real-time on-line prediction and to explain phenomenons in a similar manner