不同嚴重程度及碰撞型態之多變量高速公路事故頻次模式

Translated title of the contribution: Multivariate Freeway Crash Frequency Models by Severity Levels and Collision Types

邱 裕鈞, 傅 強(Chiang Fu)

Research output: Contribution to journalArticlepeer-review

Abstract

In addition to crash frequency analysis, crash severity and collision type are another two equally important factors that have to be assessed so as to propose effective countermeasures accordingly. Since crash severity and collision type are categorical, most of previous studies independently developed crash frequency models by severity levels and collisions types, ignoring the potential correlation among categorical levels and leading to biased estimation and lower prediction accuracy. To accommodate the potential correlation and data dispersion, this paper attempts to develop integrated models for freeway crashes across severity levels and collision types, respectively, by using the Multivariate Generalized Poisson (MVGP) model. A case study on the crash data of Taiwan NO.1 Freeway shows that the MVGP model performs significantly better than the Univariate Generalized Poisson (UVGP) model in terms of model prediction accuracy. According to estimated correlation coefficients, for crashes with severe injury levels which are Al (fatal crashes) and A2 (injury crashes) exhibit highly positive correlation. A2 and A3 (property damage only crashes) have medium positive correlation. However, Al and A3 are nearly uncorrelated. As to collision type, rear-end, sideswipe and other collision types are highly positively correlated, while collisions with roadside barriers have medium positive correlation with rear-end and sideswipe collisions, but low positive correlation with other collision types. Additionally, it is also found that the correlation effects among collision types are higher than those among severity levels. Moreover, traffic composition is identified as the common factor contributing to both collision types and severity levels. Finally corresponding countermeasures are then proposed based on the estimated parameters and elasticity of significantly tested variables.
Translated title of the contributionMultivariate Freeway Crash Frequency Models by Severity Levels and Collision Types
Original languageChinese (Traditional)
Pages (from-to)345-384
Number of pages40
Journal運輸學刊 = Journal of the Chinese Institute of Transportation
Volume27
Issue number3
DOIs
Publication statusPublished - 2015

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