Transport Simulations are a genre that has not translated to the high gloss, high production 3d game market now seen on PC and console games. However, they retain a huge following and command a niche.
As it stands, since most game publishers have lost interest in making this sort of game, what remains is almost a two horse race with a few outliers. Interestingly, both are now Open Source, so they run on Linux, Windows and Mac. This also means they are being actively developed and have huge relatively loyal communities around them.
The two main Transport Simulation games still keeping up to date are OpenTTD and Simutrans. There are others which will be briefly mentioned below. read on to see a comparison of the two, along with screenshots ,vids a few strategy tips as well as details on their community and how to get them and play them.