Sorry to hear that. And sorry to be kind of late. Weekends are for the family
So this is a quick 5 minute test. From sketchup to archiCAD. It can be done, but there are some things that have been already said.-
1. If this is a visualization project, and spans a whole city... AC is not the tool for that. AC will help with the super fast modeling of buildings (to any LOD), but roads and such will not be as easy to do, at least not to the detail you are trying to accomplish in AC.
2. I don't think anyone will ever come up with a workflow that covers what you need inside AC with the current tools. As long as AC doesn't change its core modeling algorithm (eg, ditching GDL for NURBS) the tools will just go to a certain extent.
3. The budget part can be solved using free tools, such as sketchup or blender, to model the rest of the visualization elements, but the time issue won't if you don't know any other tools besides AC.
Best regards.