code: @Pure
  	public double distance(BusItineraryHalt halt) {
  		assert halt != null;
  		final GeoLocationPoint p = getGeoPosition();
  		final GeoLocationPoint p2 = halt.getGeoPosition();
  		if (p != null && p2 != null) {
  			return Point2D.getDistancePointPoint(p.getX(), p.getY(), p2.getX(), p2.getY());
  		}
  		return Double.NaN;
  	}
docs: Replies the distance between the given bus halt and this bus halt.
  
  @param halt the halt.
  @return the distance to this bus halt