Digging a bit further ... site appears to be a joint venture between the University of Freiburg and a company called geOps, both German.

There are a bunch of things they are involved with or promoting, most listed in the blog linked under About in Travic. Knowing German helps. Here's another interesting train-related project from the blog: Visualizing a train network with GeoServer rendering transformations.

And note: while many of the systems are noted as having no real-time data, some that are so listed actually do, or at least have vehicle locations well-estimated from timetables. Sacramento RT is an example.

Now where's Amtrak? Amtrak has a nice little popup map (click on Track a Train) showing approximate locations of its various trains but they bury it in enough scripts that it's not obvious how to make a persistent or repeatable connection to it.