Horizontal curves on approach to large roundabouts

A well-designed roundabout will have an approach curve (entry curve) of less than 200m (Austroads recommendation). This is what helps reduces speeds and impact angles at a roundabout and contributes to good safety outcomes (reduced severity). The question is should these tight horizontal curves be coded within the curvature road attribute? I have seen some coding where this has occurred, but I would be concerned with this approach as it significantly increases the Run-Off and Head-On crash scores to the point where it would make well designed roundabout undesirable.

Hi Paul,

You are right to question roundabout approach’s being coded as curves.
Deflecting the approach to a roundabout is an important part of a roundabouts safety benefit. So they should not be coded as curves.

regards

James

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