In railway signaling, an interlocking is an arrangement of signal apparatus that prevents conflicting movements through an arrangement of tracks such as junctions or crossings. The signaling appliances and tracks are sometimes collectively referred to as an interlocking plant. An interlocking is designed so that it's impossible to give clear signals to trains unless the route to be used is proved to be safe. In North America, the official railroad definition of interlocking is: "An arrangement… (More on Interlocking)