The AI is certainly not very smart, but sometimes I have cities I really don't care about the minutae of: they are already fulfilling their strategic role and can suffer being mismanaged by the AI for a dozen turns.
This is also why I don't let workers automate, because they'll chop down my jungles before I have a chance to research Universities.
Just a simple if-then block like:
if (floodplains) { build farm }
if (forest) { build lumbermill }
if (jungle) { do nothing }
It wouldn't be perfect, but is obviously some sort of crappy version built-in to them that often does not do what I want, to the point that automating workers is counter-productive.
Or I'd love to be able to plot out a road/rail tile by tile and queue it up. Or heck, just a general worker queue would be an improvement even if manual.
For building roads you can use the route-to mode which works fairly well. The only caveat is that you can't tell the worker to build roads (because they're cheaper) if you have researched railroads, even if the city has a harbor so it already has the production bonus. Or it's a city state and you're only building it for the diplomacy boost.