Here is a .gif I found explaining how a single driver changing lane can disrupt traffic on a busy four lane highway.
The red car switches two lanes to its right, therefore causing those lanes, including the one it came from, to slow down.
As the lane slows down it backs up traffic behind it.
And before you know it traffic has backed up way behind it, making the cars ‘at the back’ think maybe an accident happened.
Keep in mind though, that there are many other situations similar to changing lanes that causes traffic. Cars can be parking in stores and buildings at the side, some buses and jeeps may be stopping to pick up and drop off passengers, pedestrians may be trying to cross or another vehicle just stops for any reason. It can be many different things.
The goal of this animation however is to just explain that a single disruption can cause a chain reaction, causing an effect that can go on far longer than the first event happened. That red car is long gone and traffic is still building up because of it.
Maybe this will help you think about things as you suffer through your next gridlock. In Part 2 I’ll publish a video that explains it even further.