EDIT: Roadblocks only spawn when you are in range of a city that has been chosen for roadblocks to be placed at. Turn on Debug in the Civilian Placement Module and teleport around to different cities and see if it creates a roadblock marker when doing this.

Still in, just place down

• Alive (Required) Module
• AI Commander Module
• Civilian Placement Module

and then check the roadblock setting (In the civilian placement module) to "High" and it should work. If it does work you can change the setting to whatever you feel is best suited for your mission and if it doesn't I'll link a demo mission. Make sure to also use the Debug option at the top of the civilian placement module as well, this should mark nearby roadblocks on the map.

Here is an example mission of roadblocks being used

http://www.mediafire.com/download/4so1zvmp1e3dli6/Stratis+Roadblocks+Demo.Stratis.rar