years ago, in Scientific American, the mathmatical recreations column, there was a mathmatical explaintion of the residual effect of a traffic jam.. the effect can last up to 4 hours, and it travels, not unlike the waves caused by a stone thrown into a pond.. except the pattern is linear (just a slice of the 'pond' is seen.)

and the ripple effect of slowed traffic travels in both directions, moving away from the sourse (at a speed relitive to the highway speed, and traffic volumne.

so the next time you are driving along, and suddenly traffic slows for a few hundred feet, and then resumes, with no obvious reason, you 'll recognize you have just past through a ripple left over from an accident, several miles up the road, and several hours in the past!


my other obsession