Video: What causes those bad, random traffic jams?

They can come out of nowhere and have no apparent cause.

You're driving around – it's not rush hour, there's no construction – but somehow you come upon a terrible traffic jam. 

"Must be a crash," you think to yourself. But as you slowly creep ahead, you get to a clearing and see no apparent reason for a slowdown. Suddenly, the traffic is gone and you're back to normal speeds.

So what happened?

We chatted with Minnesota Department of Transportation's work zone, pavement markings and traffic devices engineer, Ken Johnson to find out what can cause those random slowdowns. Just watch the video above. 

And if you like this video, check out GoMN's other explainers on how not to drive like an idiot in a tunnelmulti-lane roundabout, or when doing the zipper merge

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