There's a whole world of 3D train modelling out there, associated with the various train simulator programs, but I don't know if any of the data formats they use can be extracted to mainstream 3D. Most of the stuff I've seen in the Poser world has been obviously American in style. I think a lot of the modelling is done using standard tools, so you may be able to get models in a non-trainsim format if you ask. But I've a half-memory that MS Train Simulator required the use of a specific modelling program. Gmax? Train-sim models tend to be on the low-polygon end of things.