Critical horizontal curves, identified based on speed consistency (differences of typical speed between a tangent and following curve) and assessment of relation design (concordance of horizontal alignment elements), amended by road safety inspection and accident history analysis.

The identified curves were ranked on a 4-category scale. For each category, a specific optimization was proposed: either uniform road marking and signing, or horizontal alignment adjustment. The solutions are listed in the table – with more information being provided in the certified guidelines.

AVISON: An analysis of road users visibility in order to increase their safety. The analysis was computed from traffic crash data (2016-2018)

Heatmap based on traffic crashes at intersections (2016-2018). The layer represents a traffic crash overview. It is important to mention that heatmap is not a scientific method; it is only a visualization of point crash pattern (only Euclidean, not network distance of points)

ROCA (Road Curvature Analyst) is a tool for automated identification of horizontal geometry from digital vector data. It effectively identifies curves, including their radii, and tangents. The approach is based on machine learning called naive Bayesian classifier. It is a supervised learning when a training set is needed. This dataset helps to distinguish between curves and tangents. For more information about this approach see: roca.cdvinfo.cz/methodology.

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