What a lineup is when a train is ready to leave, what the signal face reads.At every terminal, when the train is ready to leave, the signals have to be ready to leave. There is a specific type of signal called a homeball. A homeball is a two face signal, with a top and bottom portion, and those are placed for switches. The top signal is for the mainline, and the bottom is for the other side of the switch.So, if a train leaves the station without switching over to another track, the homeball will be green over green.If the train is switching to another track, the signal will be green over yellow.However, when the G leaves Court Square and it has to make a double switch, the signal will be yellow over yellow.So, basically, when the train operator has the lineup, the homeball is not red over red, and also, the train s air pressure is correct (the train can t be left in the emergency brake position and the throttle has to be on), and then, the indicator light that tells the train operator that all the doors are closed is light. When all of that happens, that is when the conductor asks the train operator Do you have the line up? and then the train operator will say yes, or will give two buzzes to the conductor, and then the train will leave.
It has to to with the signals that are used to indicate one or more of the following:* that the line ahead is clear (free of any obstruction) or blocked.* that the driver has permission to proceed.* that points (also called switch or turnout in the US) are set correctly.* which way points are set.* the speed the train may travel.* the state of the next signal.* that the train orders are to be picked up by the crew.http://en.wikipedia.org/wiki/Railway_sig��Here are Subway Emergency Radio Codes you may also hear.http://411newyork.org/guide/2007/05/21/n��