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With the development of vehicle-road network technologies, the future traffic flow will appear in the form of hybrid network traffic flow for a long time. Due to the change in traffic characteristics, the current hard shoulder running strategy based on traditional traffic characteristics cannot effectively serve the hybrid network traffic flow scenario, and will even lead to the further deterioration of traffic congestion. In order to propose a hard shoulder running strategy suitable for a hybrid network environment, a traffic breakdown prediction method based on a hidden Markov model was established. Secondly, the characteristics of traffic breakdown in a hybrid network environment were analyzed. Finally, based on the traffic breakdown characteristics in a hybrid network environment, a dynamic hard shoulder running method based on the hidden Markov model was proposed. The effectiveness of HMMD-HSR was verified by simulation and comparison with HMM-HSR, LMD-HSR, and N-HSR. The simulation results show that the HMMD-HSR proposed in this paper can improve operation efficiency and reduce travel time in a congested expressway. [ABSTRACT FROM AUTHOR]

With the development of vehicle-road network technologies, the future traffic flow will appear in the form of hybrid network traffic flow for a long time. Due to the change in traffic characteristics, the current hard shoulder running strategy based on traditional traffic characteristics cannot effectively serve the hybrid network traffic flow scenario, and will even lead to the further deterioration of traffic congestion. In order to propose a hard shoulder running strategy suitable for a hybrid network environment, a traffic breakdown prediction method based on a hidden Markov model was established. Secondly, the characteristics of traffic breakdown in a hybrid network environment were analyzed. Finally, based on the traffic breakdown characteristics in a hybrid network environment, a dynamic hard shoulder running method based on the hidden Markov model was proposed. The effectiveness of HMMD-HSR was verified by simulation and comparison with HMM-HSR, LMD-HSR, and N-HSR. The simulation results show that the HMMD-HSR proposed in this paper can improve operation efficiency and reduce travel time in a congested expressway.

Featured Application: Hard shoulder running (HSR) has been increasingly used in recent years as a more sustainable way to alleviate congestion and increase the efficiency of freeways in many countries. We found that freeways experienced more crashes after installing HSR, but most of the crashes were less severe. Hence, caution should be exercised when designing and implementing hard shoulder running to reflect the trade-off between improvements in efficiency and a reduction in safety. Also, HSR installation on lengthy freeways with two travel lane configurations (without HSR) should be avoided. Hard shoulder running (HSR) has been increasingly used as a sustainable and viable way to increase road capacity. This study investigated the safety effect of HSR on freeways in South Korea using the empirical Bayes method. This study found an increase in the total number of crashes. In terms of crash severity, a higher proportion of crashes (25.3%) on 2(3)-lane sections were found to be serious (involving injuries and/or fatalities) compared to those on 4(5)-lane sections (3.6%). Also, a positive relationship was found between the length of the hard shoulder running and changes in crash frequencies. Thus, hard shoulder running on lengthy 2(3)-lane freeways should be avoided. [ABSTRACT FROM AUTHOR]

Hard shoulder running (HSR) has been increasingly used as a sustainable and viable way to increase road capacity. This study investigated the safety effect of HSR on freeways in South Korea using the empirical Bayes method. This study found an increase in the total number of crashes. In terms of crash severity, a higher proportion of crashes (25.3%) on 2(3)-lane sections were found to be serious (involving injuries and/or fatalities) compared to those on 4(5)-lane sections (3.6%). Also, a positive relationship was found between the length of the hard shoulder running and changes in crash frequencies. Thus, hard shoulder running on lengthy 2(3)-lane freeways should be avoided.

The aim of traffic management is to ensure a high quality of service for a maximum number of users by decreasing congestion and increasing safety. Uncertainty of travel times decreases the quality of service and leads end users to modify their plans regardless of the average travel time. Indicators describing travel time reliability are being developed and should be used in the future both for the optimization and for the assessment of active traffic management operations. This article discusses the efficiency of certain reliability indicators in an ex-post assessment of a traffic management strategy. Ex-post assessment is based on an observational before-after study. As some factors other than the studied management strategy may intervene between the two periods, and as most reliability indicators require knowledge of the full travel time distribution and not only its average, amethodology is developed for the identification of the impact of these exogenous factors on the whole distribution. Many reliability indicators are split into different parts allowing the identification of the part due to the management strategy impact. The methodology is tested numerically on a managed lane operation consisting of Hard Shoulder Running (HSR) at rush hour on a section of a French motorway. The variation of some reliability indicators appearsmisleading, whereas the splitting of the indicators increases our understanding of the strategy and highlights its impact. The paper gives the reliability assessment of the HSR field test and discusses different reliability indicators to identify their potential performances and shortcomings. [ABSTRACT FROM AUTHOR]

Rumble strip implementation has shown a constant increase with its safety benefits. Rumble strips are milled into the roadway shoulder to produce noise and vibrations when driven on. With the milling process, the pavement performance is expected to be negatively impacted by the decreased depth, though not mathematically quantified. Using methods defined by the Long-Term Pavement Performance Program, the severity of the shoulder site's distresses, with and without shoulder rumble strips, will be quantified. The quantification would permit the design to compensate for the impact. This design compensation allows the implementation of hard shoulder running, the use of shoulder as a travel lane during congestion, and retains the shoulder rumble strip safety instead of removing, as suggested by some proposed projects. While hard shoulder running would not impact specific time periods, the safety benefit of rumble strips could be needed at any time. This study aims to quantify the rumble strip impact to enable the full shoulder strength for hard shoulder running while retaining the safety benefits of rumble strips. [ABSTRACT FROM AUTHOR]

Hard Shoulder Running (HSR) is an operationally focused active traffic management strategy to optimize the utilization of the roadway, specifically the shoulder portion of the roadway geometry. Roadway networks needs to be more sustainable by utilizing its full capacity before using more materials to construct an expanded roadway. The understanding of the operational benefits has been the focus of much HSR research as it is an operational focused Active Traffic Management (ATM) strategy. Before HSR can be utilized, its effects on safety and the pavement structure on the shoulder need to be understood. While it has been found to improve the road operation, it must be safe and structurally sound. This paper provides a literature review of the HSR research that analyzed the safety effects and the pavement performance effects. HSR is a quality strategy that can reduce congestion, car emissions, and paved lane use requirements through improved traffic flow. [ABSTRACT FROM AUTHOR]

Abstract: Motorway operators deploy dynamic lane management operations to reduce recurrent congestions. The aim of this paper is to contribute to the safety assessment of such an operation which has been introduced on a French urban motorway weaving section. It consists in the opening of an auxiliary lane partly taken on the hard shoulder. The assessment is based on the observational before-after method in road safety, which compares the empirical number of accidents with a prediction of the number of those which would have occurred, had no change happened. A comparison site is used to identify the trend on the number of accidents between the before and after periods, independently of the effect of the operation. A variant of this method, which takes into account the traffic regimes, is developed here. This variant removes some bias, which may exist when the traffic patterns on the comparison site and on the assessed site are different. We highlight here how critical is the choice of the comparison site; how significant is the correlation between the risks of accidents by type and the traffic regimes, because that correlation, if changing over time, induces a bias; how meaningful is the provided analytic expression of the bias. Although inconclusive – due to the small number of recorded accidents – concerning the final safety impact of the operation, the main questions are discussed - reduction in traffic density leading to a reduction in the number of accidents, migration of traffic towards the opening hours, migration of density and accidents downstream. This contributes to a better understanding of the evolution of traffic safety and of the safety impact of the lane management operation. [Copyright &y& Elsevier]

Highway system is experiencing increasing traffic congestion with fast-growing number of vehicles in metropolitan areas. Implementing traffic management strategies such as utilizing the hard shoulder as an extra lane could increase highway capacity without extra construction work. This paper presents a method of determining an optimal traffic condition and speed limit of opening hard shoulder. Firstly, the traffic states are clustered using K-Means, mean shift, agglomerative and spectral clustering methods, and the optimal clustering algorithm is selected using indexes including the silhouette score, Davies-Bouldin Index and Caliski-Harabaz Score. The results suggested that the clustering effect of using K-Means method with three categories is optimal. Then, cellular automata model is used to simulate traffic conditions before and after the hard shoulder running strategy is applied. The parameters of the model, including the probabilities of random deceleration, slow start and lane change, are calibrated using real traffic data. Four indicators including the traffic volume, the average speed, the variance of speed, and the travel time of emergency rescue vehicles during traffic accident obtained using the cellular automata model are used to evaluate various hard shoulder running strategies. By using factor analysis and TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) methods, the optimal traffic condition and speed limit of opening hard shoulder could be determined. This method could be applied to highway segments of various number of lanes and different speed limits to optimize the hard shoulder running strategy for highway management. [ABSTRACT FROM AUTHOR]