Why does it seem impossible to avoid traffic jams even when traffic appears to be moving at a steady rate?
Perhaps it's because of perception and the imperfections of the human mind. Although sometimes construction and bottlenecks of road size are a lot of the problem with traffic jams, especially during rush hour, there may be some kind of mental aspect to this problem as well.
In a study, participants were asked to drive in a complete circle for a period of time, while being asked to maintain a constant speed. After some time, some cars started to exhibit fluctuating speeds. Like a domino effect, it affected every car behind it and started a chain reaction.
It seems that as soon as the traffic jam begins due to one person's impaired cognitive process, it's really hard to put an end to the chain reaction, and it causes an ongoing problem for the rest of the traffic.
It can be hard to stop a traffic jam, but you can prevent them by keeping a constant speed with cruise control and by keeping enough of a following distance to make adjustment in speed without affecting the traffic behind you.