This is what my less than perfect eye comes up with. I found an area with dense traffic, turned off all layers except GPS, and approximated what the colors were in each direction. The problem is it's really a gradient as you go through 360 degrees...

Other than showing us that someone (or lots of people when there are many tracks) traveled in a certain spot, going a certain direction, I don't know that there's much else. There doesn't appear to be a difference in length indicating speeds.

I knew it was around here somewhere. Thanks!