Much of my world-building structure originated as a post-apocalyptic concept. It was not even fantasy to begin with, but SF. Gradually it all moved away from there, fantasy elements became incorporated, and the apocalypse itself was downgraded—still a cataclysmic seismic event with earthquake and tsunamis, a set-back, but not something that reset society to zero. And no longer the start point, but one of many disasters in a long history. I'm more comfortable working with that, for now. Still, it is a usable theme, one that is far from thoroughly explored. Just probably not by me.
I have been toying with a few ideas for a post-apocalyptic fantasy, like JUST after the instigating event or within only a few years. I have looked at the various world-building aspects that most of us use to make their worlds, and then corrupt or even eliminate them if it doesn't make sense that such things would be present. Trade for example, would probably collapse for the most part. The size of communities would probably be on a much smaller scale; where once you had thousands living in one place, now it's hundreds, and likely they'd also be spread further apart. Another side effect, which is a good thing, the communities would be more self-sufficient.
With the breakdown/collapse of governments, corruption bubbles to the surface in most places, giving rise to warlords, raiders and whatnot, and the people would probably be ill-equipped to overcome them in the short term. This would also likely hinder trade even further if people don't leave their communities for fear that they'd be prey for raiders/bandits etc.
In regards to transportation, without trade and with a fear of raiders, there is little need for much of it. So wagons, carts and other modes for carrying large quantities of goods would only be necessary to carry food to local markets from the fields and probably nonexistant for other applications. This would probably include watercraft larger than fishing vessels or airships.
In my world-building project I actually kept airships; though they are uncommon. I decided to keep them because there are few threats to them now that magic is relatively nonexistant, and having raiders using them proves an interesting plotline that could be exploited.