Highlights An accurate spatial analysis of a dataset of traffic accidents lying on a directed road network is performed. Several covariates are considered at the road segment level to explain traffic accident counts through negative binomial models. Intersection and non-intersection zones are identified along the road network, and considered simultaneously to model accident counts. The interaction between intersection/non-intersection zones and covariate effects is specifically addressed. The interaction between intersection/non-intersection zones and the percentage of zeros along the network is specifically addressed. Kernel density estimation techniques are used to detect coldspots and hotspots along the road network, becoming a supplement to statistical models.
Abstract Although most of the literature on traffic safety analysis has been developed over areal zones, there is a growing interest in using the specific road structure of the region under investigation, which is known as a linear network in the field of spatial statistics. The use of linear networks entails several technical complications, ranging from the accurate location of traffic accidents to the definition of covariates at a spatial micro-level. Therefore, the primary goal of this study was to display a detailed analysis of a dataset of traffic accidents recorded in Valencia (Spain), which were located into a linear network representing more than 30 km of urban road structure corresponding to one district of the city. A set of traffic-related covariates was constructed at the road segment level for performing the analysis. Several issues and methodological approaches that are inherent to linear networks have been shown and discussed. In particular, the network was defined in a way that allowed the explicit investigation of traffic accidents around road intersections and the consideration of traffic flow directionality. Zero-inflated negative binomial count models accounting for spatial heterogeneity were used. Traffic safety at road intersections was specifically taken into account in the analysis by considering the higher variability and number of zeros that can be observed at these road entities and the differential contribution of the covariates depending on the proximity of a road intersection. To complement the results obtained from the count models fitted, coldspots and hotspots along the network were also detected, with explanatory objectives. The models confirmed that spatial heterogeneity, overdispersion and the close presence of road intersections explain the accident counts observed in the road network analyzed. Hotspot detection revealed that several covariates whose contribution was unclear in the modelling approaches may also be affecting accident counts at the road segment level.
Spatial analysis of traffic accidents near and between road intersections in a directed linear network
2019-07-26
Article (Journal)
Electronic Resource
English
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