This message indicates that a junction does not satisfy the requirement necessary to carry out Accidnet Analysis. The inscribed circle diameter, as entered in Geometric Data for each arm, must be at least 10 metres greater than the central island diameter, as entered in the accident data. In other words, the road width at each point around the roundabout must be at least 5 metres. The phrase “roundabout is non-circular” maybe confusing, but it is indicative of the fact that this message appears, more often as not, when the roundabout isn’t circular, i.e. the width of the circulating carriageway within the proximity of a particular arm is less than that of the other arms.