Traffic Waves/Stop & Go



Please explain traffic congestion on long straight, sections of highway (sans any sort of accident or construction).

Specifically, how it seems to move in waves. How is the crawl/stop created?

Then, what allows for the sections where you can get back up to 30-40 mph (briefly, before slowing again)

Finally, what’s the “tipping point” at which all of this stops and normal speeds and traffic patterns resume (seemingly out of nowhere with the same volume of vehicles)

In: Other

There can be a lot of things to cause this but normally what happens is someone is following too close and needs to tap their brakes or is cutoff by someone. This causes the person behind them to have to apply their brakes except slightly longer to maintain spacing. Repeat this process 20-30 times and all you can see in front of you is a sea of red brake lights. Seeing all of those lights alerts other drivers to slow down and you have what is called a ghost traffic jam.

That person who caused the backup by following too close is none the wiser what just happened. Normally when the traffic begins to flow again it’s roughly where that occurred.

As far as the stop and go portion I always assume it can be due to on and off ramps adding to congestion after one of these back ups. Another guess is rapid acceleration people once they find space then they start the process all over again by tapping the brakes.