Evaluating Factors of Interstate Crashes in New Jersey

Interstates in New Jersey experience a high volume of traffic, and unfortunately, around 15,000 crashes occur on these roads every year. Statistics show that 21% of these crashes result in fatalities or severe injuries. Therefore, it is critical to understand the factors contributing to this high number of crashes. This study aims to identify these factors through the application of statistical techniques.

Data was collected from the heavily traveled interstate corridors. Utilizing a Negative Binomial model, we analyzed the total number of crashes in relation to traffic, roadway geometry, and operational conditions.

As expected, factors associated with exposure, such as traffic volume and segment length, were significant. As these factors increase, crashes tend to increase. Additionally, interstates with concrete barriers exhibited fewer crashes compared to those with curbed barriers, indicating the potential benefits of concrete barriers in reducing crashes.

Interestingly, our study uncovered an aspect that is overlooked in the widely utilized safety assessment guidebook, the Highway Safety Manual – the impact of speed limits on crash frequency. Through a variable prioritization process, we identified speed limit as the second most important factor. Further exploration of the dataset revealed that crashes were more prevalent when the speed limit decreased from the previous segment on a specific interstate route. Such findings have practical implications for transportation agencies and policymakers. The insights gained can be instrumental in devising effective countermeasures, such as leveraging Intelligent Transportation Systems (ITS) to provide advance signs for speed limit changes. Implementing such measures can help mitigate crashes, particularly those associated with speed limit alterations.

Overall, this study identified the factors contributing to the high crashes on New Jersey's interstates. Understanding these factors can aid in formulating targeted strategies to improve safety of these roads.