Traffic flows in waves

Sometimes, traffic jams pop up for seemingly no reason. There’s no accident blocking a lane of traffic—but everyone comes to a halt at the same spot. Why does this happen?

Traffic can be so frustrating, and makes you want to change lanes to try to inch ahead and get around the jam. But this actually can make the traffic jam worse.

This is because traffic acts like a wave. And as it turns out, the behavior of even one car can greatly affect the wave, or even dissipate it, through counter-intuitive behaviors such as slowing down.

Here’s a fun, easy-to-understand overview of traffic waves from the perspective of a commuter who learned traffic fluid dynamics as he drove in Seattle. He discovers that just by driving a little slower than everyone else in stop-and-go traffic, he can dissipate traffic waves, and actually increase his total average speed.