1.   A mechanism to delay a phase transition until after rush hour, Kerner said, would be a big improvement.

2.   Is it a phase transition?

3.   Kerner offered no specific suggestions for blocking incipient phase transitions.

4.   Such a system would need to forecast accurately the occurrence of phase transitions that reduce traffic speed to a crawl.

5.   For example, water undergoes a phase transition when it freezes into ice.

6.   Those processes, known as phase transitions, happen whenever matter changes forms.