So you've got a bit of a Grimm Brothers set up—beginnings of an industrial revolution, but the forests are dark and dangerous. Since you have trains and riding dragons, and since travel by foot is likely to be dangerous, then major towns are probably further apart than during the Middle Ages, but closer than modern day patterns. Look at population distribution in the Midwest—Colorado's eastern slope is probably a good reference. Could be more or less based on a variety of factors. Dangerous wilderness means that smaller villages are not likely to be numerous, and they'll be closely associated with nearby stronger towns, where the villagers can flee if something comes ravening out of the night. I'm also put into mind of Peter and the Wolf.

Industry requires a lot of resources. Trains and steamboats are likely to be running on wood and charcoal, so there will be settlements closer to the trees than might otherwise be expected. Also, if this world follows our own, greed might result in clearcutting at the expense of sustainability. The Industrial Revolution destroyed most of the forests in Europe, and by the time everyone realized that the wood was almost gone, it was too late to save it.

There are probably strongly fortified small towns near borders due to the recent wars and current raiding. Depending on the prevalence of dragon power, other magic, and cannons, and the aggressiveness of the chimeras, these towns may or may not have walls, and fortresses might look like traditional castles, or they might look like star forts. Of course, much of that also depends on the manpower available to build fortifications and how much additional work can be gotten from machines and magic.