Driver performance at horizontal curves: bridging critical research gaps to increase safety

Abstract

Horizontal curve segments are locations of critical safety concern given their high crash rates. Extensive research has identified that behavioral factors influence the occurrence of such crashes. However, the most beneficial countermeasure for a curve is not always implemented or is implemented inefficiently due to a lack of full understanding of driver behavior at curves compared to tangent roadway segments. The aim of this research is to identify the conditions that impact safety at curve locations compared to tangent segment locations. This is completed through a literature review of current research relating to curve safety issues and a safety analysis of curve and tangent segment data using a novel dataset that includes curve data throughout a region. The results of this study revealed several factors that cause horizontal curves to have a higher crash rate related to driver performance, including the increased task load and demand required at curve segments compared to tangent segments, and that horizontal curve segments have an increased rate of crashes per mile with an increasing AADT compared to tangent segments. Further, horizontal curve segments along one-way operations are of increased safety concern for drivers compared to tangent segments and two-way operations. The results of this study present the conditions that can be more carefully considered in future studies and analyses to consider the human factor cause behind the increased safety issue at curve segments.

Safety Comparison of Simple and Spiral Horizontal Curves Based on Side Friction Factor Dynamic Modeling

“…After carrying out the design considerations in drawing the variants of a project and choosing the best project line, it is necessary to design horizontal curves at the road breakpoints, the type of which is selected based on the geometric design of the road [1][2][3]. Road design has undergone many changes over time, and humans have used curves at the collision of paths for purposes such as increasing safety, reducing costs, and shortening paths, one of the most common of which is simple and spiral horizontal curves [4,5]. When crossing a simple horizontal curve due to the presence of centrifugal forces, a vehicle is pushed to the curve outside, which in addition to the possibility of collision with the vehicle crossing the opposite lane, there is also the possibility of the vehicle overturning [6,7].…”