Santa Clara Tower: Dedicated to Safety

At the Santa Clara Station is a tower, which is an unusual feature for a train station.  It is the building most noticed at the station for those on the train.  I can understand a tower at an airport.  This tower was once a very important hub for train transportation as from this tower many tracks were monitored and regulated, and red lights displayed to avoid accident.  It has now been replaced by a modern looking pole of lights.  I don't know from where the train lines are monitored now, but there must be a central place with someone monitoring the trains.