Assessing the relationship between recurring and nonrecurring traffic congestion

This discussion develops an approach for using fractal geometry and diffusion limited aggregation to describe highway traffic flow. The formulation is platoon based and is most applicable for describing uninterrupted-flow facilities. The model explains empirical models in terms of fractal dimensions. The concepts of change in length of a platoon and a discrete spacing unit are described for the first time in this paper. Boundary values of various fractal dimensions are calculated for different HCM freeway LOS designations. A state of flow equation established in the model represents both microscopic and macroscopic aspects of a traffic stream. Using the same traffic flow model, recurring and nonrecurring types of congestion were quantified. A congestion evaluation index was developed to address the two types of congestion which can also be used as an performance-measure in monitoring a Congestion Management System (CMS). A few ideas were suggested for quantifying indirect benefits of CMS and furthering the present research trend.