They’re patterning them after ski trail signs; green for families and special assistance needed (beginner), blue for casual travelers (intermediate), and black for expert travelers.
This is a good idea. A family with a baby in a stroller can seriously slow down a line. Me, I can have my laptop out of the bag and personal belongings in the trays in about 20 seconds. Lines based on skill levels make sense.
This is from the TSA blog. It’s been fascinating watching their blog grow, as this behemoth and unwieldy federal agency slowly appears to be getting it that they need to be more responsive with less haphazard, bizarre restrictions that are not applied uniformly. They really do appear to be trying, and a blog is a great way to communicate.