Abstract

BULLA-CRUZ, Lenin; LYONS, Liliana  and  DARGHAN, Enrique. Complete-Linkage Clustering Analysis of Surrogate Measures for Road Safety Assessment in Roundabouts. Rev.Colomb.Estad. [online]. 2021, vol.44, n.1, pp.91-121.  Epub Feb 26, 2021. ISSN 0120-1751.  https://doi.org/10.15446/rce.v44n1.81937.

This paper presents the findings of a comparative road safety assessment between an existing two-lane roundabout and proposed basic turbo-roundabout, both designed for the same intersection, to determine which one is safer, based on traffic conflicts and surrogate safety measures. We performed microsimulation models in VISSIM to replicate the field-observed traffic operation, and the SSAM to determinate six surrogate measures. We validated the consistency of values obtained by several statistical analyzes. The number of conflicts was 72% lower at the turbo-roundabout. Through a complete-linkage clustering analysis and Euclidean distances of the surrogate measures, we found that traffic conflicts at the turbo-roundabout tend to cluster in a group, whereas conflicts at the roundabout are scattered, suggesting better organization of traffic flows at the turbo-roundabout. Three-dimensional graphical analysis of clusters and its centroids allowed verifying that surrogate measures point out a safer operation at the turbo-roundabout, even though it presented higher operating speeds. Reducing the dimensionality by principal components analysis, the cumulative variance for the first two components (87.72%) allowed observing results on a two-dimensional graph and their clusters. To endorse conflicts classification, resulting of clusters, we used discriminant analysis. Results validate the methodology and the safety benefits of the turbo-roundabout.

Keywords : Cluster analysis; Complete linkage; Discriminant analysis; Principal Component analysis; Traffic safety simulation.

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