%0 Journal Article
%T On the safety effects of spatially aggregated traffic flow parameters at macro
%A Chen Wang
%A Lin Liu
%A Zhenbo Lu
%J Advances in Mechanical Engineering
%@ 1687-8140
%D 2019
%R 10.1177/1687814018819406
%X Traffic flow parameters have been found to significantly affect crash risk at micro-levels. If such effects do exist at macro-levels, at least two benefits could be expected: (1) the performance and estimates of planning-based crash models could be improved and (2) useful safety knowledge could be provided for regional traffic management. In this article, a flow-based spatial unit was developed by a graph-cut minimization method, based on which regional management strategies are often applied. The graph-cut method partitioned the central area of Kunshan, China, into multiple sub-regions (i.e. graph-cut unit), considering traffic density homogeneity. Bayesian Poisson lognormal models with conditional autoregressive priors were utilized to examine the safety effects of traffic flow parameters, based on the traditional planning-based units and the flow-based graph-cut units. According to the results, no significant traffic flow effect was found for the traffic analysis zone¨Cbased model. Traffic flow parameters resulted in a decreased model performance and potential endogeneity issues for the census tract¨Cbased model. However, traffic flow effects were found significant for the graph-cut-based model, with an improved model performance. In general, the safety effects of macro-level traffic flow need to be considered for flow-based units developed for regional management
%K Macro-level crash modeling
%K flow-based spatial unit
%K graph-cut minimization method
%K traffic homogeneity
%K Bayesian modeling
%U https://journals.sagepub.com/doi/full/10.1177/1687814018819406