A time track mechanism is a variable player-turn order mechanism by which the player who is last on the time track goes next. The function of this mechanism can allow a player to have multiple sequential turns due to being last after each one. The basic premise is that you can choose to do a longer, slower task in the game, but in the meantime, a player taking shorter, quicker actions might change the "landscape" of the playfield. It is arguably a derivative of "action point" systems, except in the case of time tracks, the player doesn't have a fixed number of points she can or must use on her turn.
In some time track games, the active player must stop as soon as an action moves her out of the last position. In the ones with a loop for a time track, players tend to be restricted from lapping the track on one go.