You should see some of the odd ones we have in the UK. They have a large roundabout in the centre (with about a 40 metre diameter) with 6 smaller roundabouts spaced around the outside.

You have to treat each small roundabout as an individual one, meaning that you can progress around the central roundabout either clockwise or anti-clockwise.

I have never worked out the benefit of them, and I only know of two in the whole of the UK.

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Unit serial number 47 (was 330 in the queue)...