I know this isnt Trainz exactly. But if anyone has or plays Chris Sawyer Locomotion there has been development on a open source for it, like OpenTTD. If you like OpenTTD or Transport Fever I highly recommend this game and its only 6 bucks on steam. You can then update your copy to OpenLoco which adds newer windows support and adds many nice features lacking in the original release like building when paused and no vehicle breakdowns.
Here is a link on how to get OpenLoco running on your version: https://steamcommunity.com/app/356430/discussions/0/4768721849826772242/
Here is a link on how to get OpenLoco running on your version: https://steamcommunity.com/app/356430/discussions/0/4768721849826772242/