Comment by lynx__

The directors and organizers of the race control what the lights do. Typically they work with a specific athlete or group of athletes to hit a World Record, National Record, or Meet Record pace.

They are almost always even splits, with a consistent pace through the entire race, though this can be adjusted if the runners request it; that is rare though.

They typically have green lights, which is the target pace, and then a set of blue lights ahead of them, which gives a visual indicator of how far ahead a runner is from the green lights.