At 02:12 PM 1/10/2011, John C... wrote:
>Has anyone noticed that cars seem to "bunch" up?
>They get close to each other and travel for miles that way?
>With 5 miles to another "pack" behind them.
>Must be some sort of phenomenon !!!  heh... heh...

Perfectly normal.  It's easier to "keep station" on another vehicle
than to actually drive at a constant speed, cruise control
excepted.  So the traffic flow quite unconsciously sorts itself out
into pods of vehicles whose intended speeds were within 2-3 mph of
each other.  The longer the road, the bigger the pods.  They grow
from the rear, of course, and anything can disturb them.

Yours,
David