MOD STILL BROKEN. I have a working version locally but it takes some time to polish into a satisfactory state...

It's a gantry crane that sits on top two parallel elevated rails for loading/unloading cargo train / ships while balancing out your storages at the same time! Place the gantry crane supports parallel to your train station / port and make sure the midpoint between two segments sits on top of your storage (shown when hovering on the gantry vehicle) and the crane will automatically load onto or unload from the train, depending on the setting.