private void addFreight() {
			boolean valid = false;
			String input = "";
			int weight = 40;
			Object[] goodsType = { "General Goods", "Refrigerated Goods",
					"Dangerous Materials" };
			
			do {
				input = (String)JOptionPane.showInputDialog(null,
						"Specify Carriage Weight (tonnes)\n" +
						"Between 40 and 200", "Carriage Weight",
						JOptionPane.INFORMATION_MESSAGE, null, null, 40);
				try { 
			        weight = Integer.parseInt(input);
			        if (weight >= 40 && weight <= 200) {
			        	valid = true;
			        }
			    } catch(NumberFormatException e) { 
			        valid = false;
			    }
			} while (!valid);
			
			String goods = (String)JOptionPane.showInputDialog(null,
					"Choose the type of goods this\n" +
					"Freight Carriage will carry.",	"Goods Type",
					JOptionPane.INFORMATION_MESSAGE, null,
					goodsType, goodsType[0]);
			
			switch (goods) {
	        case "General Goods"		: goods = "G";
	        	break;
	        case "Refrigerated Goods"	: goods = "R";
         		break;
	        case "Dangerous Materials"	: goods = "D";
	        	break;           
			}
			
			try {
				Train.addCarriage(new FreightCar(weight,  goods));
			} catch (TrainException e) {
				errorHandler(e);
			}
		}