Zip Lines are interactive objects found on top of some buildings and structures in the City of Glass in Mirror's Edge. Though they're supposed to be used as connecting cables, Runners used these lines as better transportation. When the player jumps onto the lines, they automatically grab onto the line. The player will descend to the opposite end of the rope.
There are different types of Zip Line endings. One is the easiest, where the players descend until they get to a metal structure (or wall) that holds the opposite end. The second requires timing, where the end of the line have no solid ground under it for players to land on. This type needs players to let go of the rope earlier well-timed to land onto an object that is safer to land onto.
Please note that Zip Lines could only work when the player is higher on one side than the opposite. The Lines turn red when the Runner Vision is on. Sliding down is faster than sprinting, though it is short-lived.