Workers won't stop making forts!

[joncnunn]

What I do is click on "leave existing improvements" + "don't remove forest", and until it's very late in the game I manually move every worker; at that point I start the auto connect orders that add some more rail routes.

Note that Forts do provide the resource so if it's a tile never to be worked by a city it's not the worst improvement in the world.