Factorio Forums

Is there some information available on different train lenghts and which is the most optimal? What is the impact of extra wagons? When to add an extra locomotive? Etc...

Apart from that I think a train with three wagons usually enough.

This thread has a comparison and discussion of locomotive/wagon ratio:
https://forums.factorio.com/forum/vie ... =18&t=8145

Short story is - if you want to maintain absolute maximum speed, you need 1 locomotive for every 2 wagons. Where you put the locomotives does not matter for the speed, only for your station design.

I personally never use more than 3 wagons. The simple reason is that station layout becomes complex to setup (not so much in terms of cost complexity, but in terms of clicking/fiddling)