Soldato
I had the same issue with mine too, you need lots of generic industry to supply goods to commercial as there's a limit to the amount of goods your city can import (I found this out by replacing all my industry with office zones and it nearly killed the city).
Industry buildings won't upgrade unless they are functioning, and won't function unless they have the right staff. Level 1 industry depends on uneducated people to work and won't take many over educated people, once it gets to level 3 the staff work/education balance is fine for a developed city. Basically your educated citizens don't want to work in the mill, but the mill won't upgrade unless it's already working.
To build more industry areas, zone the area, make sure it has services and entertainment, good transport links (2 bus routes to anywhere and rail/tube), also cargo train terminal too if your city supports it. To populate it you'll need to de-zone a large chunk of residential then re-zone it again, essentially kicking out educated people from your city and replacing them with uneducated who will migrate back with the new development.
This new lower class will then work in your industry at level1, allowing it to develop to level 3 where the educated will want to work.
I've tried building shanty towns (residential with no services) to try and keep an uneducated workforce for all new industry developments but somehow they still manage to send their kids to school.
Industry buildings won't upgrade unless they are functioning, and won't function unless they have the right staff. Level 1 industry depends on uneducated people to work and won't take many over educated people, once it gets to level 3 the staff work/education balance is fine for a developed city. Basically your educated citizens don't want to work in the mill, but the mill won't upgrade unless it's already working.
To build more industry areas, zone the area, make sure it has services and entertainment, good transport links (2 bus routes to anywhere and rail/tube), also cargo train terminal too if your city supports it. To populate it you'll need to de-zone a large chunk of residential then re-zone it again, essentially kicking out educated people from your city and replacing them with uneducated who will migrate back with the new development.
This new lower class will then work in your industry at level1, allowing it to develop to level 3 where the educated will want to work.
I've tried building shanty towns (residential with no services) to try and keep an uneducated workforce for all new industry developments but somehow they still manage to send their kids to school.
