AAP revised_paper_final.pdf (1.3 MB)
Impacts of speed variations on freeway crashes by severity and vehicle type
journal contribution
posted on 2018-12-11, 10:57 authored by Pushpa Choudhary, Marianna Imprialou, Nagendra R. Velaga, Alok ChoudharyAlok ChoudharySpeed variations are identified as potentially important predictors of freeway crash rates; however, their impacts on crashes are not entirely known. Existing findings tend to be inconsistent possibly because of the different definitions for speed variations, different crash type consideration or different modelling and data aggregation approaches. This study explores the relationships of speed variations with crashes on a freeway section in the UK. Crashes split by vehicle type (heavy and light vehicles) and by severity mode (killed/serious injury and slight
injury crashes) are aggregated based on the similarities of the conditions just before their occurrence (condition-based approach) and modelled using Multivariate Poisson lognormal regression. The models control for speed variations along with other traffic and weather variables as well as their interactions. Speed variations are expressed as two separate variables namely the standard deviations of speed within the same lane and between-lanes over a five minute interval. The results, similar for all crash types (by coefficient significance and sign), suggest that crash rates increase as the within lane speed variations raise, especially at higher traffic volumes. Higher speeds coupled with greater volume and high between-lanes speed variation also increase crash likelihood. Overall, the results suggest that specific combinations of traffic characteristics increase the likelihood of crash occurrences rather than their individual effects. Identification of these specific crash prone conditions could improve our understanding of crash risk and would support the development of more efficient safety countermeasures.
Funding
This research is partially supported by the European Union Europe Aid-funded Project “EU-India Research & Innovation Partnership for Efficient and Sustainable Freight Transportation (REINVEST),” Contract Number: R/141842.
History
School
- Business and Economics
Department
- Business
Published in
Accident Analysis and PreventionVolume
121Pages
213 - 222Citation
CHOUDHARY, P. ... et al., 2018. Impacts of speed variations on freeway crashes by severity and vehicle type. Accident Analysis and Prevention, 121, pp. 213-222.Publisher
© ElsevierVersion
- AM (Accepted Manuscript)
Publisher statement
This paper was accepted for publication in the journal Accident Analysis and Prevention and the definitive published version is available at https://doi.org/10.1016/j.aap.2018.09.015.Acceptance date
2018-09-14Publication date
2018-09-25ISSN
1879-2057Publisher version
Language
- en