It happens to most drivers at least a few times a year. You are sailing along on the highway or expressway or freeway when you are suddenly forced to come to a stop, or at least a crawl. You can't see why things are slowing around the bend. And when you get there, traffic is moving better. Check this out to learn why and what is the term for that occasion.
So what do u think of the "shockwave" and the funnel effect? New terms huh? Please don't feel bad because you are not the only one who not know about this :)