Locate the power button on your computer and toggle it to the off position.
Thats it! Should work.

this has been tested on a windows 10 PC.

Power off does indeed stop the Railroader application but has the side effect of closing all applications as well. This may result in loss of data that has not been saved to disk. There may be a cleaner way to do this.

So for now, perhaps shutting the game down the normal way may be best until this method is 100% ironed out....but this one step method is still the quickest way I've found.