Crash Prediction on Horizontal Curves: Review and Model Performance Comparison

Abstract

More than 25% of all roadway fatalities in the U.S. are associated with a horizontal curve, and the average crash rate for horizontal curves is about three times that of other types of highway segments. A focus on horizontal curves can prove to be a cost-effective approach to reducing safety issues. Accurate crash prediction models (CPMs) on horizontal curves can help roadway safety practitioners assess and prioritize safety improvements. Although many CPMs have been developed, there are no extant studies that compare different CPMs on a singular, real-world, large-scale, and comprehensive dataset to evaluate their capability for horizontal curve crash prediction. This study critically evaluated commonly used CPMs, including multiple linear regression (MLR), Poisson regression (PR), negative binomial regression (NBR), support vector machine, random forest (RF), and fully connected neural network (FCNN) models, on rural curves extracted from 18,000 centerline miles of Georgia, U.S.’s state-maintained routes and statewide historical crash data set from 2013 to 2021. Results show PR and NBR models outperform MLR by around 6%. Moreover, the FCNN and RF models further improved this performance by around an additional 6% over the PR and NBR models. Overall, machine learning (ML)-based models outperform generalized linear regression models. The results prove ML-based models can be recommended to transportation agencies to forecast horizontal curve crashes more accurately.