West Palm beach, fl had large round abouts installed about 10y ago and I thought that was great, except with little traffic at the time it seemed wasteful in time navigating and more importantly in space. I think the idea is great though, it&#x27;s safe and usually gives everyone a fair shot to get moving without much delay.. I&#x27;d be interested in knowing how the diameter of the round about is decided on, specifically is it some algorithm based on predicted traffic congestion numbers.