A Model of the Probability of a Cross-Median Crash When a Vehicle Fully Crosses the Median

• Published in: Transportation research record 2018-12, Vol.2672 (39), p.34-40
• Main Authors: Carrigan, Christine E., Ray, Malcolm H.
• Format: Article
• Language: English
• ISSN: 0361-1981; 2169-4052
• DOI: 10.1177/0361198118758310

The consequences of cross-median crashes are often catastrophic but crashes into median barriers can also be severe. Wide medians provide traversable space where vehicles can recover or stop but sometimes even wide medians can be crossed over. Determining if a median barrier is needed at a particular site involves balancing the risks associated with crossing completely over the median and striking a vehicle in the opposing lanes with the risks of an errant vehicle striking a median barrier. Median crossover crashes can be viewed as a conditional probability model: first the vehicle must enter the median; second, the vehicle must cross completely over the median; third, a vehicle must be in the opposing lanes where it is struck and, finally, there is a chance of a severe or fatal injury if all these conditions are met. All the elements of this conditional probability model are documented in the literature except the third; the probability of a crash with an opposing-direction vehicle given that a vehicle has completely traversed the median. Estimating this probability is the subject of this paper.