Complexity

Roundabouts come in a handful of forms, from very simple to quite complex. They're all "hazards", so use the same principle for each.

Here are the factors which make them increasingly complicated:

(1)  single-lane approach
(2)  slip-road / dedicated lanes
(3)  multi-lane approaches
(4)  non-symmetrical
(5)  multi-lanes through
(6)  non-circular
(7)  blocked views
(8)  altered priorities

(9)  exits close together
(10)  sloping ground
(11)  yellow boxes
(12)  spiral (= non-circle lanes)
(13)  protected/hatched areas
(14)  traffic-light control
(15)  varying lanes
(16)  combination of features