Features of the “stop-and-go” phenomenon are found. First, the local phase transition “free flow $\to$ synchronized flow” is realized. Then the “pinch effect” in synchronized flow occurs. In the pinch region a complex sequence of narrow jams is self-formed. The following transformation of the narrow jams into wide jams determines a scale in distances between stop-and-go patterns.

• Received 17 December 1997

DOI:https://doi.org/10.1103/PhysRevLett.81.3797