Recently, hysteretic transitions to “synchronized traffic” with high values of both density and traffic flow were observed on German freeways [B. S. Kerner and H. Rehborn, Phys. Rev. Lett. 79, 4030 (1997)]. We propose a macroscopic traffic model based on a gas-kinetic approach that can explain this phase transition. The results suggest a general mechanism for the formation of probably the most common form of congested traffic.

• Received 3 March 1998

DOI:https://doi.org/10.1103/PhysRevLett.81.3042