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Title: Impact of data aggregation approaches on the relationships between operating speed and traffic safety
Authors: Yu, Rongjie
Quddus, Mohammed A.
Wang, Xuesong
Yang, Kui
Keywords: Speed and crashes relationship
Bayesian random-effects model
Urban expressway traffic safety
Crash aggregation approach
Issue Date: 2018
Publisher: © Elsevier
Citation: YU, R. ... et al, 2018. Impact of data aggregation approaches on the relationships between operating speed and traffic safety. Accident Analysis and Prevention, 120, pp.304-310.
Abstract: The impact of operating speed on traffic crash occurrence has been a controversial topic in the traffic safety discipline as some studies reported a positive association whereas others indicated a negative relationship between speed and crashes. Two major issues thought to be accountable for such conflicting findings are the application of inappropriate statistical methods and the use of sample datasets with varying levels of aggregation. The main objective of this study is therefore to investigate the impacts of data aggregation schemes on the relationships between operating speed and traffic safety. A total of three aggregation approaches were examined: (1) a segment-based dataset in which crashes are grouped by roadway segment, (2) a scenario-based dataset where crashes are aggregated by traffic operating scenarios, and (3) a disaggregated crash-level dataset consisting of information from individual crashes. The first two aggregation approaches were used in examining the relationships between operating speed and crash frequency using Bayesian random-effects negative binomial models. The third disaggregated crash risk analysis was conducted utilizing Bayesian random-effects logistic regression models. From the modeling results, it has been concluded that the scenario-based approach shared similar findings with those of the disaggregated crash risk analysis approach in which a U-shaped relationship between operating speed and crash occurrence was identified. However, the commonly adopted segment-based aggregation approach revealed a monotonous negative relationship between speed and crash frequency. The implications of the different analyses results and the potential applications of the results on speed management systems have therefore been discussed.
Description: This paper is closed access until 5 September 2019.
Sponsor: This study was jointly sponsored by the Chinese National Natural Science Foundation (NSFC 71771174 and 71531011) and the 111 Project (B17032).
Version: Accepted for publication
DOI: 10.1016/j.aap.2018.06.007
URI: https://dspace.lboro.ac.uk/2134/36521
Publisher Link: https://doi.org/10.1016/j.aap.2018.06.007
ISSN: 0001-4575
Appears in Collections:Closed Access (Architecture, Building and Civil Engineering)

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