Most of my projects include rebuilding roads, sidewalks etc. from Google Maps/Earth in order to get the surrounding area right for our new buildings.
I have some models prepared that i can combine via Boxmodeling.
I experimented with Splines and Sweep Modifier but it is more difficult to connect different Road Types since the meeting edges are not prepaired for connecting like my prepared models via Box Modeling.
I often need to be able to change curve radius of new roads. I saw some Tutorials on Youtube an Google about Creating Roads with Blender but most dont tackle the task of turnings.
Not sure what you mean by turnings. Just a thought (I’m no expert at this sort of thing): I use a bezier curve and an array modifier to create some simple roads (see picture), but you could do more detailed modeling and get good results.The start and end caps could be used to make intersections, forks, lane drops, etc.