In addition to all the other advice about sussing when to be assertive and when to back off from confrontation, I find this to be hugely helpful.

Generally, in all traffic situations, I make sure every driver in my vicinity looks me in the eye. I make exaggerated head-turns and pause for a second so that everyone knows that everyone sees each other. It is almost like a lion-taming trick; you can sort of use your eyes as a tractor-beam to move cars around. And when you run into a fool that does not care about your welfare, you find out quickly and can make a secondary decision whether or not to assert my position. Generally, the effectiveness of this technique is based on sense of shared humanity, rarely does it have a flavor of intimidation.

Given our relative lack of horsepower and armor in this struggle, its usually best to make the contest as personal as possible. Nothing arrests the distracted thoughts of a human more than the gaze of another human.

jim