An optimal variable speed limits system to ameliorate traffic safety risk

Yu, Rongjie; Abdel-Aty, Mohamed

doi:10.1016/j.trc.2014.05.016

Cited by 120 publications

(60 citation statements)

References 23 publications

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“…This is most probably the result of fewer accidents that resulted in a reduction in travel time. The RCP algorithm has been evaluated through microscopic traffic simulation [29,30,56]. The results presented in [29,30] show a trade-off between safety, measured as decreased crash potential and traffic efficiency, measured as total time spent.…”

Section: Variable Speed Limit Algorithms In This Studymentioning

confidence: 99%

“…The results presented in [29,30] show a trade-off between safety, measured as decreased crash potential and traffic efficiency, measured as total time spent. Also, it is concluded in [30] and [56] that there are threshold values for the crash potential for which benefits in terms of both safety and efficiency can be made. In a field trial of SPECIALIST [17] it is shown that the algorithm is able to resolve around 80% of the identified shockwaves with a gain in travel time as a result.…”

Section: Variable Speed Limit Algorithms In This Studymentioning

confidence: 99%

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Characteristics of variable speed limit systems

Grumert

Tapani

2018

Eur. Transp. Res. Rev.

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The control algorithm used for deciding on the speed limit in variable speed limit systems is crucial for the performance of the systems. The algorithm is designed to fulfil the purpose of the variable speed limit system, which can be one or several of the following aspects: increasing safety, increasing efficiency and decreasing environmental impacts. Today, many of the control algorithms used in practice are based on fixed thresholds in speed and/or flow. Therefore, they are not necessarily reflecting the current traffic conditions. Control algorithms with a greater level of complexity can be found in the literature. In this paper, four existing control algorithms are investigated to conclude on important characteristics affecting the performance of the variable speed limit system. The purpose of the variable speed limit system and, consequently, the design of the control algorithm differ. Requirements of the investigated control algorithms are that they should be easy to interpret and the execution time should be short. The algorithms are evaluated through microscopic traffic simulation. Performance indicators related to traffic safety, traffic efficiency and environmental impacts are presented. The results show that the characteristics of the variable speed limit system and the design of the control algorithm will have effect on the resulting traffic performance, given that the drivers comply with the variable speed limits. Moreover, the time needed to trigger the system, the duration and the size of speed limit reductions, and the location of the congestion are factors of importance for the performance of variable speed limit systems.

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Section: Variable Speed Limit Algorithms In This Studymentioning

confidence: 99%

Section: Variable Speed Limit Algorithms In This Studymentioning

confidence: 99%

Characteristics of variable speed limit systems

Grumert

Tapani

2018

Eur. Transp. Res. Rev.

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“…The advantages of this MPC approach have been made clear through its adoption in several subsequent VSL studies (Zhang et al, 2005;Popov et al, 2008;Hegyi et al, 2008;Hegyi and Hoogendoorn, 2010;Ghods et al, 2010;Carlson et al, 2010bCarlson et al, , 2011Carlson et al, , 2012. In a recent study, Yu and Abdel-Aty (2014) used an extension of the METANET model to optimize VSL values to minimize the total crash risk. The study concluded that the proactive VSL system was able to improve traffic safety by decreasing crash risk and enhancing speed homogeneity under both the high and moderate compliance levels.…”

Section: Literature Reviewmentioning

confidence: 99%

Variable speed limit: A microscopic analysis in a connected vehicle environment

Khondaker

Kattan

2015

Transportation Research Part C: Emerging Technologies

235

103

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a b s t r a c tThis paper presents a Variable Speed Limit (VSL) control algorithm for simultaneously maximizing the mobility, safety and environmental benefit in a Connected Vehicle environment. Development of Connected Vehicle (CV)/Autonomous Vehicle (AV) technology has the potential to provide essential data at the microscopic level to provide a better understanding of real-time driver behavior. This paper investigated a VSL control algorithm using a microscopic approach by focusing on individual driver's behavior (e.g., acceleration and deceleration) through the use of Model Predictive Control (MPC) approach. A multi-objective optimization function was formulated with the aim of finding a balanced trade-off among mobility, safety and sustainability. A microscopic traffic flow prediction model was used to calculate Total Travel Time (TTT); a surrogate safety measure Time To Collision (TTC) was used to measure instantaneous safety; and, a microscopic fuel consumption model (VT-Micro) was used to measure the environmental impact. Real-time driver's compliance to the posted speed limit was used to adjust the optimal speed limit values. A sensitivity analysis was conducted to compare the performance of the developed approach for different weights in the objective function and for two different percentages of CV. The results showed that with 100% penetration rate, the developed VSL approach outperformed the uncontrolled scenario consistently, resulting in up to 20% of total travel time reductions, 6-11% of safety improvements and 5-16% reduction in fuel consumptions. Our findings revealed that the scenario which optimized for safety alone, resulted in more optimum improvements as compared to the multi-criteria optimization. Thus, one can argue that in case of 100% penetration rates of CVs, optimizing for safety alone is enough to achieve simultaneous and optimum improvements in all measures. However, mixed results were obtained in case of lower % penetration rate which showed higher collision risk when optimizing for only mobility or fuel consumption. This indicates that with such % penetration rate, multi-criteria optimization is crucial to realize optimum and balanced benefits for the examined measures.

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“…The optimization of VSL proved to improve the traffic flow and capacity. The VSL optimization was also proposed and developed to improve traffic safety by homogenizing the traffic flow given different driver compliance rates [7].…”

Section: Literature Reviewmentioning

confidence: 99%

Optimal Variable Speed Limit Control under Connected Work Zone and Connected Vehicle Environment

Du¹,

Razavi²,

Genders³

2017

Proceedings of the International Symposium on Automation and Robotics in Construction (IAARC)

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Despite the long-term benefits gained through road maintenance projects, the work zone involved can cause serious traffic congestion and greatly increase traffic delay. Variable speed limit (VSL) enforcement provides a means to reduce the travel time and alleviate the traffic congestion in work zones. This paper presents a novel proactive VSL control algorithm for freeway work zone traffic management under connected work zone and connected vehicle environment. In a connected work zone environment, the estimated work zone capacity can be easily shared considering the work zone configuration factors such as number of lane closure, signal distance, presence of work activity, etc. After incorporating the estimated capacity which contributes to a better modeling of the traffic disturbance caused by work zone, the traffic flow predictive model was established to obtain preventive measures and avoid traffic breakdown. In addition, based on the trajectories of individual vehicles recorded and shared by connected vehicles, the objective function was developed for the VSL control algorithm to minimize the Total Travel Time which can be used to measure level of the traffic congestion. The VSL control was implemented and tested in a traffic simulator SUMO. The results showed that the designed VSL algorithm effectively decreased the total travel time with the reduction of the speed variance which potentially improved the traffic safety at work zones.

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An optimal variable speed limits system to ameliorate traffic safety risk

Cited by 120 publications

References 23 publications

Characteristics of variable speed limit systems

Characteristics of variable speed limit systems

Variable speed limit: A microscopic analysis in a connected vehicle environment

Optimal Variable Speed Limit Control under Connected Work Zone and Connected Vehicle Environment

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