Why Do Traffic Jams Happen?

And as long as everyone is moving at a normal speed, traffic is good.

But sometimes there's something called [car hooting] a traffic jam.

A traffic jam is that thing where you, you look out your window of the car and you don't see the thing that you normally see.

You know how you normally see buildings and trees moving really quickly past the window? Well, when you're in a traffic jam, you probably notice that your car is barely moving at all.

In fact, you might not be moving, period.

[sirens wailing] A traffic jam can happen when too many cars are trying to get through the same area at the same time.

Roads are only designed to handle so many cars.

So why is it that sometimes you drive down a road and you can move really fast? [car driving] But other times you have to drive down that same road moving really slowly.

And then something even stranger.

Have you ever been stuck in traffic for a long time, and then just suddenly everybody started moving again? [car driving] You look around for the thing that caused the traffic and there's nothing there.

How does that happen? I was thinking about all of this today because I got a question from a kid in the Curious Kids Club named Charlie.

Charlie was curious... "Hi, Josh.

How does traffic happen? Why does the first car stop? Bye, Josh." [upbeat music] Okay, so think about the road you're traveling on right now, like a really big hallway.