Turner-Fairbank Highway Research Center

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Analysis of head-on crash injury severity using a partial proportional odds model

Product Type

Journal Article


Pengfei Liu and Wei (David) Fan



Full citation

Liu, P. & Fan, W.D. (2021). Analysis of head-on crash injury severity using a partial proportional odds model. Journal of Transportation Safety & Security 13(7), 714-734.


Head-on crashes are one of the most severe crash types and always result in injuries or fatalities. To prevent and mitigate head-on crashes, factors that significantly affect the injury severity of head-on crashes must be identified before appropriate countermeasures can be explored. To bridge the gap between ordered and unordered response modeling, in this research, a partial proportional odds model is developed to analyze the factors that influence the injury severity of head-on crashes. The analyses are performed based on the data collected from Highway Safety Information System (HSIS) from 2005 to 2013 in North Carolina. The results of this research demonstrate that there are 14 factors that have significant effects on the injury severity of head-on crashes. Among them, the roadway with speed limit over 50-mph is found to increase the fatal crash most. Appropriate countermeasures are recommended according to the influencing factors that are identified. The model performance is also compared with ordered logit model and multinomial logit model. The partial proportional odds model can provide adequate fit without potential loss of prediction accuracy.

Available From

Journal of Transportation Safety & Security

Link To Journal Article

Link not available.


Head-on crashes
Severity analysis
Partial proportional odds model
Ordered logit model
Multinomial logit model

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HSIS Summaries

HSIS Summary Reports are two to eight pages in length and include a brief description of the issue addressed, data used, methodology applied, significant results, and practical implications.

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Research Reports

A variety of research studies have been performed using data from HSIS. Many of the final reports prepared are now available electronically.

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Technical Summaries

Research reports are often summarized in executive summaries, technical briefs, or other abbreviated formats. Included here are those road safety summaries that involved research using HSIS data.

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Safety Analysis Tools

In addition to conducting research, HSIS resources are also used to develop products that can be used by practitioners in the analysis of safety problems.

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Other Projects

HSIS data are sometimes used in research studies that result in other types of finished products, such as dissertations, theses, and conference proceedings.

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