public static synchronized TrainScheduleManager instance() {
   if (_instance == null) {
     if (log.isDebugEnabled()) {
       log.debug("TrainScheduleManager creating instance");
     }
     // create and load
     _instance = new TrainScheduleManager();
     TrainManagerXml.instance(); // load trains
   }
   if (Control.SHOW_INSTANCE) {
     log.debug("TrainScheduleManager returns instance " + _instance);
   }
   return _instance;
 }
 protected void setDirtyAndFirePropertyChange(String p, Object old, Object n) {
   TrainManagerXml.instance().setDirty(true);
   pcs.firePropertyChange(p, old, n);
 }