[ABC]

I am sure Roundabout size is taken into consideration when the Engineers design them, i cannot imagine any reason why they would place 2 lanes on a roundabout that was not big enough for 2 lanes, as i have said before the 2 lanes are there for a reason!

I agree there are much larger roundabouts across the world but the traffic lanes on TV 2 lane roundabouts i have encountered are more than adequate in size for 2 vehicles side by side and for vehicles to be able to use them in the correct manner, e.g. to be in the correct lane according to the exit you wish to take and yield to traffic that has right of way over you.