Work zones on the United States highway system interrupt regular traffic flows and create safety problems. Improving safety without sacrificing themain function of highways is a challenging task that traffic engineers and researchers have to confront. In this study, the concept of using crash severity index (CSI) for work zone safety evaluation was proposed and a set of CSI models were developed through the modeling of work zone crash severity outcomes. A CSI is a numerical value between zero and one that is estimated from given work zone variables. It is interpreted as the likelihood of having fatality/fatalities when a severe crash occurs in a given workzone. The CSI models were developed using a three-step approach. First, awide range of crash variables were examined in a comprehensive manner andthe significant risk factors that had impact on crash severity were selected. Second, the CSI models were developed using logistic regression technique by incorporating the selected risk factors. Finally, the developed models were validated using the recent crash data and their ability in assessing work zone risk levels were analyzed. Results of this study showed that CSI values can provide straightforward measurements of work zone risk levels. Applying such models for risk-level assessment in either an existingwork zone or a newly proposed work zone will provide traffic engineers anopportunity to identify work zone risks, and thus, enable them to deploy safety countermeasures in advance to prevent the occurrence of severe crashes.
Abstract