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Only constraint in building this was that it had to be 3x3 chunks (so 96x96 tiles). 180-degree rotationally symmetric. Prioritises straight-through traffic, with the inner lanes being straight-through exclusive. Bottleneck is the turning lanes and merging, by design of course. Power poles were just to help with grid alignment and don't serve any functional purpose.

This turbine design is rotationally symmetric in a 3x3 chunk space, with the 'downside' that not all lanes can go in all directions and there is no turnaround. 90-degree rotationally symmetric. However, throughput is good and I usually build this in my maps with a separate lane-changer on the entrances/exits to this intersection.