A crossover is a secondary tunnel cut between the two main tunnels. In the case of the Niagara Frontier Transportation Authority's Metro Rail Line, these tunnels cross over from the inbound and outbound tunnels. There are three crossovers in this system consisting of; the Allen-Hospital crossover, The Humboldt-Hospital crossover and the University crossover. So how does it work? Well if there is a need to shut down, lets say the inbound track at a point between the Allen-Hospital Station and the Delevan-College Station then the controller would simply re-route the inbound trains through the Humboldt-Hospital crossover, down the outbound track and then back onto the inbound track through the Allen-Hospital crossover. This is called single tracking because the inbound trains and outbound trains share the same track.

I know what your thinking. Who in the world is the controller and how does he keep the inbound and outbound trains from colliding, causing mass destruction, carnage and chaos? First of all the controller is a person who sits in a warm, cushy seat in an office with a computerized board that tells exactly where all the trains are running in the entire system. He has the power to control the train crossovers by just pushing a button. The locations of the trains are done electronically through the use of magnetic locators. When a train passes over the locator, it sends a signal to the controller's locator board and that's how he knows where and when to push his buttons, activating the crossover switch tracks. The controller also is the person who's voice is heard over the stations public address system, instructing passengers which track the next train will be departing from. There are also emergency call boxes located throughout the system so one can call the controller, just in case he or she forgot to drink their coffee and sent the trains on the wrong track or gave out the wrong passenger information. This of course, the NFTA wants us all to know, never happens.