@floris Your approach in modeling the interchange using very large, somewhat arbitrary shaped surfaces and then trimming those surfaces is interesting and unusual.
An alternative approach would be to first create centerline curves for the roadways at the desired shapes and elevations. The surfaces for the roadways could be created from the the centerline curves using several different approaches. One would be offset the centerlines to create curves at the edges of the roadways, and use Loft to create surfaces from the edge curves. Another would be to create cross-section lines/curves of the roadway and use Sweep1 to create the road surfaces. The latter approach would allow the road surfaces to be tilted on the curves, ie cant/camber/superelevation. After surfaces are created for each individual roadway segment the segments could be blended together with transition sections added as needed.
[quote=“floris, post:7, topic:38596”]
@davidcockey When I use Scale1D or ScaleNu like in the Rhino tutorial, it won’t work. I cannot understand why.
[/quote] I use both commands frequently without any problems. Without a video of you attempting to use the commands it is impossible to know why they don’t work for you.