Effects of Traffic Control Devices on Rural Curve Lateral Position

Abstract

This study investigated, by means of a dynamic driving simulator experiment, road users’ behavior inside the curves of rural two-lane highways related to different advance warning signs, perceptual measures, and delineation treatments. These treatments were intended to warn drivers of the presence of low radius curves and to affect their behavior, improving vehicle control and lane-keeping. Five surrogate measures of safety were used in the evaluation of the design alternatives in relation to lateral position performance: standard deviation of lateral position, maximum encroachment in the shoulder, maximum encroachment in the opposite lane, relative length of shoulder encroachment, and relative length of opposite lane encroachment. Statistical tests were performed to verify whether the surrogate measures of safety were significantly different between alternatives. The analysis was divided into three phases. In the first phase, all the measures were preprocessed, testing normality and homoscedasticity assumptions. In the second phase, the presence of an overall effect considering all the alternatives was evaluated using analysis of variance and the Kruskal–Wallis test. In the third phase, Student’s t- and Mann–Whitney tests were used to assess which alternatives showed statistically significant effects. The results demonstrated that the perceptual measures, namely colored transverse strips, dragon teeth markings, and colored median island, were the most effective treatments. Field tests to establish the perceptual measures’ effectiveness on real roads are strongly advised. Implementation of the measures tested in the driving simulator should be carried out on similar rural highways to validate the results.

Exploring Factors Affecting Crash Injury Severity with Consideration of Secondary Collisions in Freeway Tunnels

“…For example, guidelines could be developed for designing tunnels or installing various tunnel facilities, such as improved lighting to reduce temporary ocular blindness in tunnels, technological approaches to warn against the loss of speed sense due to the low illumination and monotonous environment, operational strategies for incident rescue teams to reduce injury severities for longer tunnels, and operational plans for variable message signs in tunnels to reduce secondary collisions by providing crash information in advance. Additionally, simple traffic control devices for driver attention guidance and speed reduction, such as warning signs, perceptual treatments, and delineation treatments, can also help to positively reduce injury severities and secondary collisions [ 89 ]. Moreover, as noted by Rella Riccardi, et al [ 90 ], educational campaigns can be an excellent tool to motivate drivers to undertake safety-oriented behavior in freeway tunnels.…”

Design Issues in Widening of Unspiraled Horizontal Curves

“…An independent spiral may be needed, they said, for the outside edge as well to be in harmony with vehicle tracks. Attention was drawn to the behavior of curve cutting as drivers tend to shift their vehicles laterally across the lane when negotiating horizontal curves (21)(22)(23). However, using a spiraled pavement edge (or a modified spiral, derived from parabolic, cubic or compound curves) for an unspiraled horizontal curve has not attracted much interest, probably because it undermined the simplicity of unspiraled layout design.…”

Effects of Speed Reduction Marking Patterns on Simulated Driving Speed and Lane Position

“…In fact, the researchers observed a lower SDLP in high-workload conditions than in low-workload conditions, using an auditory working memory task. In a recent work, Galante et al ( 44 ) reported colored transverse markings, “dragon teeth” markings, and painted medians as the best perceptual treatments to improve lane-keeping measured by SDLP. Nonetheless, little research has thoroughly investigated SDLP or the driver’s visual attention across multiple patterns of speed reduction markings.…”

“…The participants in this study were primarily recruited on a college campus with a limited budget, meaning they were relatively young and perhaps inexperienced compared to the general driver population. Although the participants were daily drivers, literature reports that young male drivers are often associated with riskier driving (55)(56)(57)(58), while another study reports smaller SDLP at horizontal curves among female drivers and older drivers (44). Therefore, it would be ideal for future research to include larger samples from a different or more general driver population to overcome these limitations associated with age, gender, or education.…”