Helbing and co-workers have identified six different traffic phases: homogeneous congestion, oscillatory congestion, triggered stop-and-go traffic, moving localised clusters, pinned localised clusters, and free traffic. One axis of their phase diagram represents the flow of vehicles already on the motorway, while the other represents vehicles joining the motorway. Transitions between the states are triggered by localised event - such as a convoy of slow moving lorries passing the intersection. The boundaries between the different phases are related to various properties of the traffic flow such as the density of vehicles.

According to group's simulations, the occurrences of traffic jams can be reduced by adjusting various properties of the intersections where vehicles join the motorway.