Why traffic waves and congestion happen

Posted to Infographics  |  Tags: , ,  |  Nathan Yau

You’re on the freeway, traffic is moving along, and for no apparent reason everyone slows down. And eventually, for no apparent reason, traffic starts back up again. What the what? Lewis Lehe and Matthew Green explain why these waves occur with a couple of interactives.

The simplest explanation for why traffic waves happen is that drivers have relatively slow reaction times: if the car in front of you suddenly slows down, it’ll likely take you a second or so to hit the brakes. The slower your reaction time, the harder you have to brake to compensate and keep a safe distance. The same goes for the car behind you, which has to brake even harder than you did in order to slow down faster. And so on down the road, in a domino-like effect.

Hit the brakes in the simulation, and you’ll see what happens. Naturally this is a simplified version of traffic conditions and assumes some things about how people drive and react, but you’ll get the idea.

It might remind you of this real world experiment a few years ago.

Favorites

Interactive: When Do Americans Leave For Work?

We don’t all start our work days at the same time, despite what morning rush hour might have you think.

Divorce Rates for Different Groups

We know when people usually get married. We know who never marries. Finally, it’s time to look at the other side: divorce and remarriage.

Unemployment in America, Mapped Over Time

Watch the regional changes across the country from 1990 to 2016.

Real Chart Rules to Follow

There are rules—usually for specific chart types meant to be read in a specific way—that you shouldn’t break. When they are, everyone loses. This is that small handful.