Implementation of Active Traffic Management Strategies for Safety on Congested Expressway Weaving Segments

2017 ◽  
Vol 2635 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Ling Wang ◽  
Mohamed Abdel-Aty ◽  
Jaeyoung Lee
Keyword(s):  
Traffic Safety ◽  
Traffic Management ◽  
Management Strategies ◽  
Ramp Metering ◽  
Assessment Model ◽  
Variable Speed ◽  
Analysis Model ◽  
Variable Speed Limit ◽  
Average Travel Time ◽  
The Impact

In weaving segments, traffic merges, diverges, and weaves in a limited space. These traffic maneuvers might result in high crash hazards. To improve the safety of a congested expressway weaving segment, this study tested various active traffic management (ATM) strategies in microsimulations. Crash odds and the Surrogate Safety Assessment Model were used to evaluate the impact of ATM strategies on traffic safety. The crash odds were calculated based on the real-time safety analysis model for weaving segments. The strategies included ramp metering (RM), variable speed limit (VSL), and integrated RM and VSL (RM-VSL). Overall, the results showed that the ATM strategies improved the safety of the studied weaving segment. The modified ALINEA RM algorithms, which took lane occupancy and safety into consideration, outperformed the traditional ALINEA algorithm from a safety perspective. The 45 mph VSLs, which were located at the upstream of the studied weaving segment, significantly enhanced safety without notably increasing average travel time. A consolidated RM-VSL strategy was also proposed with the aim of improving traffic safety by implementing RM and VSL. In the consolidated RM-VSL strategy, the modified ALINEA RM was adjusted according to the queue length to prevent long queues on ramps. The results proved that the consolidated RM-VSL strategy reduced the number of conflicts by 16.8% and decreased the crash odds by 6.0%.

Variable speed limit strategies analysis with link transmission model on urban expressway

2018 ◽  
Vol 32 (06) ◽  
pp. 1850077 ◽  
Author(s):  
Shubin Li ◽  
Danni Cao
Keyword(s):  
Traffic Safety ◽  
Traffic Congestion ◽  
Management Strategies ◽  
Simulation Method ◽  
Average Density ◽  
Transmission Model ◽  
Speed Limit ◽  
Variable Speed ◽  
Variable Speed Limit ◽  
Urban Expressway

The variable speed limit (VSL) is a kind of active traffic management method. Most of the strategies are used in the expressway traffic flow control in order to ensure traffic safety. However, the urban expressway system is the main artery, carrying most traffic pressure. It has similar traffic characteristics with the expressways between cities. In this paper, the improved link transmission model (LTM) combined with VSL strategies is proposed, based on the urban expressway network. The model can simulate the movement of the vehicles and the shock wave, and well balance the relationship between the amount of calculation and accuracy. Furthermore, the optimal VSL strategy can be proposed based on the simulation method. It can provide management strategies for managers. Finally, a simple example is given to illustrate the model and method. The selected indexes are the average density, the average speed and the average flow on the traffic network in the simulation. The simulation results show that the proposed model and method are feasible. The VSL strategy can effectively alleviate traffic congestion in some cases, and greatly promote the efficiency of the transportation system.

An Economic and Risk Analysis Model for Aircrafts and Engines

2007 ◽  
Author(s):  
D. S. Pascovici ◽  
F. Colmenares ◽  
S. O. T. Ogaji ◽  
P. Pilidis
Keyword(s):  
Economic Model ◽  
Traffic Management ◽  
Short Range ◽  
Spare Parts ◽  
Assessment Model ◽  
Analysis Model ◽  
Global Warming Impact ◽  
Confidentiality Agreement ◽  
The Cost ◽  
The Impact

To conceive and assess engines with minimum global warming impact and lowest cost of ownership in a variety of emission legislation scenarios, emissions taxation policies, fiscal and Air Traffic Management environments, a Techno-economic and Environmental Risk Assessment model is needed. This paper presents an approach to estimate the cost of maintenance and the direct operating costs of turbofan engines of equivalent thrust rating, both for long and short range applications, as well as for typical long and short range aircraft. The economic model is composed of three modules: a lifing module, an economic module and a risk module. The lifing module estimates the life of the high pressure turbine disk and blades through the analysis of creep and fatigue over a full working cycle of the engine. The economic module uses the time between overhauls together with the cost of labour and the cost of the engine (needed to determine the cost of spare parts) to estimate the cost of maintenance of the engine. The risk module uses the Monte Carlo method with a Gaussian distribution to study the impact of the variations in some parameters on the net present cost (NPC) of operation. The accuracy of the economic model in DOC estimation is good (within about 15%) and so can be adapted for use in the cost analysis of future types of engines, such as ultra high bypass ratio turbofans, with little modifications. The equations that constitute the economic model are under a confidentiality agreement of the European project VITAL and can not be divulgated.

scholarly journals Integrated variable speed limit and ramp metering control study on flow interaction between mainline and ramps

2019 ◽  
Vol 11 (3) ◽  
pp. 168781401983191 ◽  
Author(s):  
Xu Wang ◽  
Lei Niu
Keyword(s):  
Traffic Safety ◽  
Integrated Control ◽  
Simulation Models ◽  
Ramp Metering ◽  
Speed Limit ◽  
Variable Speed ◽  
Variable Speed Limit ◽  
Error Sources ◽  
Prediction And Simulation ◽  
Varying Demand

During peak periods, bottlenecks are often triggered by excessive demand from both on-ramp and mainline input flows. To relieve bottleneck severity and improve traffic safety, ramp metering and variable speed limit are implemented to control the on-ramp and mainline input flows, and sometimes they are integrated. This article presents a proactive integrated control, with goals to save network-wide travel time and increase traffic flow. A METANET-based macroscopic traffic model was adopted as a prediction model. Micro-simulation tests were performed to evaluate and compare the control approaches among integrated and isolated control scenarios. By decoupling the traffic prediction and simulation models, the control error sources were analyzed. The evaluation revealed that both isolated and integrated controls benefit the traffic network to different extents under varying demand scenarios. Under proactive integrated control, ramp metering is activated solely during slight congestion; or it is activated during high-congestion periods to assist variable speed limit and thus integration maximizes the infrastructure utility.

scholarly journals Variable Speed Limit and Ramp Metering for Mixed Traffic Flows: A Review and Open Questions

2021 ◽  
Vol 11 (6) ◽  
pp. 2574
Author(s):  
Filip Vrbanić ◽  
Edouard Ivanjko ◽  
Krešimir Kušić ◽  
Dino Čakija
Keyword(s):  
Traffic Control ◽  
Ramp Metering ◽  
Transport Infrastructure ◽  
Control Algorithms ◽  
Speed Limit ◽  
Mixed Traffic ◽  
Traffic Flows ◽  
Variable Speed ◽  
Variable Speed Limit ◽  
Traffic Demand

The trend of increasing traffic demand is causing congestion on existing urban roads, including urban motorways, resulting in a decrease in Level of Service (LoS) and safety, and an increase in fuel consumption. Lack of space and non-compliance with cities’ sustainable urban plans prevent the expansion of new transport infrastructure in some urban areas. To alleviate the aforementioned problems, appropriate solutions come from the domain of Intelligent Transportation Systems by implementing traffic control services. Those services include Variable Speed Limit (VSL) and Ramp Metering (RM) for urban motorways. VSL reduces the speed of incoming vehicles to a bottleneck area, and RM limits the inflow through on-ramps. In addition, with the increasing development of Autonomous Vehicles (AVs) and Connected AVs (CAVs), new opportunities for traffic control are emerging. VSL and RM can reduce traffic congestion on urban motorways, especially so in the case of mixed traffic flows where AVs and CAVs can fully comply with the control system output. Currently, there is no existing overview of control algorithms and applications for VSL and RM in mixed traffic flows. Therefore, we present a comprehensive survey of VSL and RM control algorithms including the most recent reinforcement learning-based approaches. Best practices for mixed traffic flow control are summarized and new viewpoints and future research directions are presented, including an overview of the currently open research questions.

Assessing the mobility benefits of proactive optimal variable speed limit control during recurrent and non-recurrent congestion

2015 ◽  
Vol 42 (7) ◽  
pp. 477-489 ◽  
Author(s):  
Ying Luo ◽  
M. Hadiuzzaman ◽  
Jie Fang ◽  
Tony Z. Qiu
Keyword(s):  
Traffic Control ◽  
Propagation Speed ◽  
Speed Limit ◽  
Variable Speed ◽  
Variable Speed Limit ◽  
Detection Delay ◽  
Traffic Performance ◽  
Total Travel Time ◽  
Variable Speed Limit Control ◽  
The Impact

Over the past few decades, several active traffic control methods have been proposed to improve freeway efficiency at bottleneck locations. Variable speed limit (VSL) is one of these effective controls. Previous studies have evaluated VSL control, but primarily during recurrent congestion only. This study focuses on evaluating the performance of VSL control for both recurrent and non-recurrent congestion. To assess the effectiveness of a previously proposed VSL control in a real-world situation, this study has three evaluation objectives: (1) examine the control performance when recurrent and (or) non-recurrent congestion occurs; (2) assess the effectiveness of the control when a queue encounters the VSL sign; and (3) consider the impact of system detection delay in VSL control. Comparative experiments for Whitemud Drive in Edmonton, Alberta, Canada, are simulated in the VISSIM platform, and traffic performance is compared among scenarios with and without control. The simulation results show that VSL improves mobility for both recurrent and non-recurrent congestion. The VSL control reduces total travel time, and improves total travel distance and total flow. Furthermore, it slows down the shockwave propagation speed, improves the average speed on most of the freeway segments, and reduces the duration of traffic recovery.

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