It's further out, or if you walk long enough in any direction you come to it.

[He points to the last tendrils of steam coming from the train.] In this case coal is burned to heat water which produces steam. That steam creates pressure which moves a piston which in turn moves the wheels. [You wanted a full explanation right?] They aren't used much at all where I come from as we have different power sources, but they were used briefly in the past. [And in countries that were not rich in Sakuradite.]

I can draw you a map if you wish though there is no guarantee our worlds look the same.

[An eyebrow raise at the name.] I am Suzaku Kururugi, my lord.