A New GNB Model of Crash Frequency for Freeway Sharp Horizontal Curve Based on Interactive Influence of Explanatory Variables

Abstract

Crash prediction of the sharp horizontal curve segment of freeway is a key method in analyzing safety situation of freeway horizontal alignment. The target of this paper is to improve predicting accuracy after considering the elastic influence of explanatory variables and interaction of explanatory variables on crash rate prediction. In the paper, flexibility and elasticity are defined to express the elastic influence of explanatory variables and interaction of explanatory variables on crash rate prediction. Thus, we proposed 6 types of models to predict crash frequency. These 6 types of models include 2 NB models (models 1 and 2), 2 GNB models (models 3 and 4), one NB model (model 5), and one GNB model (model 6) with flexibility and variable elasticity considered. The alignment and crash report data of 88 sharp horizontal curve segments from different institutions were surveyed to build the crash models. Traffic volume, highway horizontal radius, and curve length have been assigned as explanatory variables. Subsequently, statistical analysis is performed to determine the model parameters and conducted sensitivity analysis by AIC, BIC, and Pseudo R2. The results demonstrated the effective use of flexibility and elasticity in analyzing explanatory variables and in predicting freeway sharp horizontal curve segments. In six models, the result of model 6 is much better than those of the other models by fitting rules. We also compared the actual results from crashes of 88 sharp horizontal curve segments with those predicted by models 1, 3, and 6. Results demonstrate that model 6 is much more reasonable than the others.

Exploring the Impact of Rainfall on Vehicle Trajectory Patterns and Sideslip Risk: An Empirical Investigation

“…(1) Turning beneft ratio: Te turning beneft ratio TBR as a classifcation indicator refers to the ratio of the trajectory's approximate radius to the ideal radius, as shown in equation (7). According to the coordinates of the starting point (x s , y s ), midpoint (x m , y m ), and endpoint (x e , y e ) of the trajectory in the x-y coordinate system, the approximation radius R T can be computed using Heron's formula [58], as shown in equation (8).…”

“…Te reasons behind the frequent crashes under rainy conditions not only lie in the reduced skid resistance leading to longer braking distances for vehicles but also in the fact that vehicles easily sideslip on curved segments [5]. Previous studies have shown that rainfall can increase the expected number of severe crashes on curved segments by 3.26 times [6,7]. Terefore, comprehending the impact of rainfall on vehicle sideslip risk on curved segments is crucial for enhancing road design and trafc safety management.…”

Risk Distribution Characteristics and Optimization of Short Weaving Area for Complex Municipal Interchanges

“…e configuration and alignment of the road also have a greater impact on traffic safety. Wang et al [18,19] analyzed the road safety of expressways and highways under different alignment combination conditions. erefore, in the present paper, the common weaving area configuration, that is, a three-lane and ramp double-in, single-out urban interchange with auxiliary lanes, is analyzed in this paper [20].…”