-locomotives would need water + coal, or steam to ride,
-locomotives get a smal bar in the GUI that indicates how much water and steam ther is inside
-locomotives could be filled with water with a new sort of pump station that hangs over the rails
-new tank-cart that holds steam (witch the train can ride on) or water (that can be comebined with coal to make steam)
-new coal-cart, a little cart (about 1/3 of a normal cart (that can hold extra coal for the locomotive)
-water tower, a tower that holds water or steam (2x2) that can be pumped in and out
the water pump for the locomotive :

let me know what you think
