A Random-Parameter Negative Binomial Model for Assessing Freeway Crash Frequency by Injury Severity: Daytime versus Nighttime

Ping Zhang, Chenzhu Wang, Fei Chen, Suping Cui, Jianchuan Cheng and Wu Bo
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Ping Zhang: School of Engineering, Tibet University, No. 36 Jiangsu, Lhasa 850000, China
Chenzhu Wang: School of Transportation, Southeast University, 2 Sipailou, Nanjing 210096, China
Fei Chen: School of Transportation, Southeast University, 2 Sipailou, Nanjing 210096, China
Suping Cui: School of Engineering, Tibet University, No. 36 Jiangsu, Lhasa 850000, China
Jianchuan Cheng: School of Transportation, Southeast University, 2 Sipailou, Nanjing 210096, China
Wu Bo: School of Engineering, Tibet University, No. 36 Jiangsu, Lhasa 850000, China

Sustainability, 2022, vol. 14, issue 15, 1-16

Abstract: This study explored the effects of contributing factors on crash frequency, by injury severity of all, daytime, and nighttime crashes that occurred on freeways. With three injury severity outcomes classified as light injury, minor injury, and severe injury, the effects of the explanatory variables affecting the crash frequency were examined in terms of the crash, traffic, speed, geometric, and sight characteristics. Regarding the model estimations, the lowest AIC and BIC values (2263.87 and 2379.22, respectively) showed the superiority of the random-parameter multivariate negative binomial (RPMNB) model in terms of the goodness-of-fit measure. Additionally, the RPMNB model indicated the highest R 2 (0.25) and predictive accuracy, along with a significantly positive α parameter. Moreover, transferability tests were conducted to confirm the rationality of separating the daytime and nighttime crashes. Based on the RPMNB models, several explanatory variables were observed to exhibit relatively stable effects whereas other variables presented obvious variations. This study can be of certain value in guiding highway design and policies and developing effective safety countermeasures.

Keywords: crash frequency; freeway crash; random-parameter approach; elasticity effects (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2022
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (1)

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