i've had to animate a train recently. i looked at all the procedural methods of road building, but being a bear of small brain i had to come up with a ‘traditional’ houdini method of getting a train to run on tracks.

i draw a curve, polyspline it, even lengths. make it into a creep path. run another, short, line along it, deleting all but the end points. I copy the train bogies to these points, so the bogies follow the railway lines, which lie in a section of track/landscape, copied and creep'd along the same path. i scale the ‘bogie’ line (which is just two points, so it scales along its axis), make IT into a creep path (resample for more points), scale it so I get some overhang on the bogies, then creep the carriage of the train into this box, making sure it's the original proportions, likewise the engine, creep'd a bit further along. this way the all the wheels run along the tracks, and the engine and carriages looked parented to TWO bogies.

is there an easier way? it looks perfect for my application, but if it were film fx?