Inner City Motorways/Freeways
Duplicates the default country roads (motorways) as city roads in the game for aesthetic purposes. This will stop the AI changing inner city motorways to streets.
In order to stop the AI building on the motorways, and connecting roads to them, you should use your usual method of AI building control. I personally recommend the Fences mod by CPU Skully, listed below.
Fences Mod by CPU | Skully
For tips on how to prevent the AI touching inner city motorways, Episode 38 of my Transport Fever Midlands series on YouTube will show you all you need to know.
YouTube – Episode 38, Includes example uses