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Revista Colombiana de Estadística

Print version ISSN 0120-1751

Rev.Colomb.Estad. vol.44 no.1 Bogotá Jan./June 2021  Epub Feb 26, 2021 

Original articles of research

Complete-Linkage Clustering Analysis of Surrogate Measures for Road Safety Assessment in Roundabouts

Análisis de conglomerados mediante vecinos más lejanos en medidas sustitutas para la evaluación de seguridad vial en glorietas

Lenin Bulla-Cruz1  a 

Liliana Lyons2  b 

Enrique Darghan3  c 

1Department of Civil and Agricultural Engineering, Faculty of Engineering, Universidad Nacional de Colombia, Bogotá, Colombia

2Department of Civil and Agricultural Engineering, Faculty of Engineering, Universidad Nacional de Colombia, Bogotá, Colombia

3Department of Agronomy, Faculty of Agricultural Sciences, Universidad Nacional de Colombia, Bogotá, Colombia


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.

Key words: Cluster analysis; Complete linkage; Discriminant analysis; Principal Component analysis; Traffic safety simulation


Este artículo presenta los hallazgos de una evaluación comparativa de seguridad vial entre una glorieta clásica existente y una turboglorieta propuesta, en la misma intersección, para determinar cuál es más segura, con base en conflictos de tráfico y medidas sustitutas. Elaboramos modelos en VISSIM para recrear la operación del tráfico observada en campo y SSAM para determinar seis medidas sustitutas. Validamos la consistencia de los resultados por varios análisis estadísticos. El número de conflictos fue 72% menor en la turboglorieta. Mediante un análisis de conglomerados de las medidas sustitutas, los conflictos en la turboglorieta tienden a agruparse en un clúster, mientras que en la glorieta éstos están dispersos, sugiriendo una mejor organización de los flujos de tráfico en la turboglorieta. El análisis gráfico tridimensional de conglomerados y centroides permitió verificar que las medidas sustitutas indican una operación más segura en la turboglorieta, a pesar de presentar velocidades de aproximación más altas. Reduciendo la dimensionalidad, mediante análisis de componentes principales, la varianza acumulada de los dos primeros componentes (87.72%) permitió observar los resultados en dos dimensiones. Mediante análisis discriminante, respaldamos la clasificación de conflictos resultante de los clústeres. Los resultados validan la metodología y los beneficios en seguridad de la turboglorieta.

Palabras clave: Análisis de componentes principales; Análisis de conglomerados; Análisis discriminante; Simulación de la seguridad vial; Vecino más lejano

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