For those that have a Nuvi with traffic info, I found this cool legend.

"I’m not sure how many folks actually take the time to review Garmin’s traffic symbol legend. When you’re fighting traffic probably isn’t the best time to do it, and it’s not that simple to find the legend either. First of all you have to have the traffic receiver connected and receiving, so there’s no way to try it in the comfort of your living room. And then you have to find it (Apps > Traffic > Menu > Legend on the newest models). So to make things easier for you, I’ve compiled them all here…"