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The presentation of in-vehicle warnings information at risky driving scenarios is aimed to improve the collision avoidance ability of drivers. Existing studies have found that driver’s collision avoidance performance is affected by both warning information and driver’s workload. However, whether moderation and mediation effects exist among warning information, driver’s cognition, behavior and risky avoidance performance is unclear.

This purpose of this study is to examine whether the warning information type modifies the relationship between the forward collision risk and collision avoidance behavior. A driving simulator experiment was conducted with waring and command information.

Results of 30 participants indicated that command information improves collision avoidance behavior more than notification warning under the forward collision risky driving scenario. The primary reason for this is that collision avoidance behavior can be negatively affected by the forward collision risk. At the same time, command information can weaken this negative effect. Moreover, improved collision avoidance behavior can be achieved through increasing drivers’ mental workload.

The proposed model provides a comprehensive understanding of the factors influencing collision avoidance behavior, thus contributing to improved in-vehicle information system design.

The significant moderation effects evoke the fact that information types and mental workloads are critical in improving drivers’ collision avoidance ability. Through further calibration with larger sample size, the proposed structural model can be used to predict the effect of in-vehicle warnings in different risky driving scenarios.

This study aims to investigate the safety effects of work zone advisory systems. The traditional system includes a dynamic message sign (DMS), whereas the advanced system includes an in-vehicle work zone warning application under the connected vehicle (CV) environment.

A comparative analysis was conducted based on the microsimulation experiments.

The results indicate that the CV-based warning system outperforms the DMS. From this study, the optimal distances of placing a DMS varies according to different traffic conditions. Nevertheless, negative influence of excessive distance DMS placed from the work zone would be more obvious when there is heavier traffic volume. Thus, it is recommended that the optimal distance DMS placed from the work zone should be shortened if there is a traffic congestion. It was also revealed that higher market penetration rate of CVs will lead to safer network under good traffic conditions.

Because this study used only microsimulation, the results do not reflect the real-world drivers’ reactions to DMS and CV warning messages. A series of driving simulator experiments need to be conducted to capture the real driving behaviors so as to investigate the unresolved-related issues. Human machine interface needs be used to simulate the process of in-vehicle warning information delivery. The validation of the simulation model was not conducted because of the data limitation.

It suggests for the optimal DMS placement for improving the overall efficiency and safety under the CV environment.

A traffic network evaluation method considering both efficiency and safety is proposed by applying traffic simulation.

Purpose – Freeway networks are designed to higher standards and are safer infrastructures as compared to other road types, if properly designed. On the other hand, these facilities are driven at very high speeds and therefore speed and design consistency are essential for achieving safe infrastructure designs. This chapter describes the criteria for speed and design consistency and looks at new tools and criteria for improving freeway safety in new and in existing infrastructures.

Methodology – This chapter describes the criteria to evaluate if there are speed, design and human factors inconsistencies, as well as potential solutions for tackling local deficiencies and speeding issues. As one of the critical issues in freeway safety is represented by run-off-road crashes, a specific section in the chapter is devoted to newly developed design and assessment tools for improving roadside safety. The potential implications of Intelligent Transportation System (ITS) technologies on freeways design and management are also presented.

Findings and Social Implications – The important crash reduction trends observed in the decade 2001–2010 are now slowing down and new actions are required to be coupled with more traditional design checks. The full implementation of cooperative ITS systems is expected to have a very important impact on road safety, but in the short term several safety improvements can be realised: section speed enforcement techniques and high-friction wearing courses have been proven to be extremely effective, as have perceptual measures accounting for human factors principles.