Let Tim Carter, of Ask the Builder, tell you.
“Here’s the bottom line if you look at the above facts.
The traffic congestion during periods of peak flow will be the same or worse with the roundabouts.
All you have to have is one or two timid tourists who are NOT FAMILIAR with the merging and aggressive tactics you need to use in periods of HEAVY TRAFFIC to transform one or more approaches into the roundabout into GRIDLOCK.
If you’ve never been parked behind a person afraid to enter a roundabout, you’ll forever remember it when it happens to you. It’s very frustrating as they hold up ALL the traffic behind them.
Aggressive driving increases in roundabouts in periods of heavy flow as impatient drivers force their way into the roundabout.”