private void buildVerticalRoads() {
		_verticalRoads = new VehicleAcceptor[_gridDimensions.getColumn()][_gridDimensions.getRow()+1];
		//[column][row]
	    for (int j=0; j<_gridDimensions.getColumn(); j++) {
	      for (int i=0; i<=_gridDimensions.getRow(); i++) {
	    	  VehicleAcceptor l = VehicleAcceptorFactory.newRoad();
	        l.setOrientation(VehicleOrientation.North_South);
	        _verticalRoads[j][i] = l;
	      }
	    }
	    
	}