Originally posted by: SickBeast
The causes of the "waves" are twofold:
1. Cars weaving in and out of lanes.
2. Cars entering and exiting the freeway.
The cause of a jam is usually an accident or adverse weather, but that's just common sense.
There are other causes that I have not seen mentioned (the unseen in the above linked). That would be poor driving habits and driver expectations. But that can possibly be the same thing. I have observed the start of waves (I always forgot what they were called and used to refer to them as pulses )
A bad driver can solely cause a wave in traffic ripe for it be over-reacting to a situation. Usually is some smuck that over-brakes for a non-situation. The over-reaction causes a driver behind that is following too close to react in kind. The drivers in the next lanes, seeing the brake lights, react to this imaginary event. Bingo, surfs up. Baaahhhhhha (sound of sheep in a flock).
Also, after a series of waves, waves can then self-generate further down the highway. Again, poor habits and expectations combined with visibility. If a pack of drivers just had the carp scared out of them because of braking hard for a stoppage, later applications of brakes in a situation where visibilty is questionable, will cause them to over-react. Holiday traffic is notorius for this on I-75 to Florida. A backup would occur because of construction and 3-2 lane reductions. Some of the hills or crossovers then cause a blind jam that scares some folks (and a little tire smoke). Later, as the pack has started rolling again, someone will crest a bridge and hit their brakes. No braking is required, they could just be using the brake to suspend their cruise control. But because of the situation, some smuck will react. The rest of the sheep see the one sheep leap in the air and they react. New wave with no incident in site and well beyond the initial event.
Oh, and that link has a couple things not quite right. First, a plug can cause serious issues with traffic if the lanes are +1 around the plug. You seen this on 4 lanes where a plug is going slower than most of the traffic. It will force even the "nonaggressive" drivers to eventually react and slow the flow of both lanes. There can be miles of backup because someone is towing a trailer at 50 on the interstates.
He is also missing a piece of behavior in the big merges, Spagetti Junction in Atlanta is a good one (I-85N where I-285 merges.) Today, when traffic hits its peak, there will be a jam at the merges. What he does not understand is that one of the fastest lanes of travel is the extreme right lane (1). What? There is where all the traffic is merging, how can that be? Everyone merging immediately gets out of 1 and moves over. In fact, lane 5 and the HOV lane can slow to be the worst. All the merge traffic is "trying" to avoid getting "stuck" in the merge traffic. While doing so, they leave a vacuum in lane 1 and 2 (1 exits in 2 miles). When not using the HOV lane, I can go to the right lane and then work back starting about 1.5 miles later and skip lots of traffic. The trick there is now folks have finished the big merge (and moved to the left) and are then setting up to exit and the next series of exits (moving right). On Friday, lane 4 can move faster than lane 5 well past the merge because of a combination of all of the above and the fact that there are just too many dolts that think they are fast traffic and moving right is for other folks (3 and 5 series BMW, Lexus, and Mercedes E class drivers seem to be a substantial part of this population - freaking Type As.)
I love queueing theory
Definition - Over-braking - apply the brakes in such a fashion as to increase the following interval above what is reasonable. If a car is following at the 2 second rule and the driver then over-reacts and puts 4 seconds and then more into the gap, they have over-braked for the situation. These drivers also do not use their mirrors, so pass with care.