We added a new science: The Rolling Stock Forge. When you activated it, you can clone your rolling stock for $$. So you can have more trains without the need to buy them for diamonds!
Note that the Forge can only clone locomotives, coaches or cargo wagons if you have at least one of that type and only if they are available in the year of play.
Have fun playing and have a nice christmas!
Xmas Update!
Source: Steam Community (opens in a new tab)