 Nassau line Chambers Street monitors?
Some J and M trains short-turn at Chambers Street. Those monitors are so the
conductor can see the front and rear car doors of the train. Only the middle
tracks at Chambers Street relay trains in a way that mimics the usual travel
pattern of the station.
Although is this one of the few stations were all tracks can terminate and
relay a train in either direction. In fact this is one of the few stations
where such a usage was a "regular feature" of the station.
Mike
| 
