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Proactive Traffic Merging Strategies for Sensor-Enabled Cars VANET 2007, September, 2007 Ziyuan Wang, Lars Kulik and Kotagiri Ramamohanarao Department.

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Presentation on theme: "Proactive Traffic Merging Strategies for Sensor-Enabled Cars VANET 2007, September, 2007 Ziyuan Wang, Lars Kulik and Kotagiri Ramamohanarao Department."— Presentation transcript:

1 Proactive Traffic Merging Strategies for Sensor-Enabled Cars VANET 2007, September, 2007 Ziyuan Wang, Lars Kulik and Kotagiri Ramamohanarao Department of Computer Science and Software Engineering The University of Melbourne, Australia

2 2 Outline Introduction Problem Statement Progress So Far Future Directions

3 3 Traffic Congestion Some facts on traffic congestion Total amount of delay: 3.7 billion hours in 2003 Wasted fuel: 2.3 billion gallons lost Congestion cost: $63 billion Source: Texas Transportation Institute, 2005 Urban Mobility Report.

4 4 Major Causes of Congestion Source: Federal Highway Administration. Traffic Congestion and Reliability: Linking Solutions to Problems - Executive Summary. Bottlenecks: Intersections of on-ramps and main roads Blockage due to obstacles slinky type effect

5 5 Emergence of VANETs Sensor-Enabled Cars Spatial information Dedicated Short-Range Communications (DSRC) Vehicle-to-Vehicle (V2V) Vehicle-to-Roadside (V2R) Vehicular Ad hoc Networks (VANETs) Safety: less accidents Efficiency: higher road utility Position Speed Acceleration Deceleration

6 6 Problem Statement Goal Optimize traffic throughput How Proactive traffic merging algorithms Technology available: sensor-enabled cars + VANETs Applications Intersections at the ramp and the main road of highways (Highway merge assistant) Lane changing when there are obstacles on the way

7 7 Existing Approaches Traffic signal timing Fixed Traffic-responsive Ramp metering Real-time information Automation Fully: Platoon (tightly grouped cars) Partial: Adaptive Cruise Control (ACC) Limitations Adaptive Flexible Robust Traffic conditions are highly variable and unpredictable

8 8 Contributions Proposed proactive traffic merging algorithms that aim to use the current road facilities efficiently Designed a controlled simulation environment intended to test various traffic merging strategies Investigated what criteria are significant to evaluate the performance of traffic merging algorithms

9 9 Proactive Merging Algorithm Highway bottleneck Regular strategy Local decision Distance-based Velocity-based A B X Y A B X Y A B X Y Regular Proactive

10 10 Outline of Our Algorithms Strategy InformationRight of WayAssumption Distance-basedPositionThe car that is closest to the merging point Velocity does not vary much Velocity-basedPosition Velocity The car that arrives to the merging point first Acceleration does not vary much Comparisons of the proactive merging algorithms

11 11 Outline of Our Algorithms Sliding decision point Adjust speed appropriately Output { c, d, x, e, y } { c, x, d, y, e } { x, c, d, y, e } Input { c, d, e } { x, y } Merging strategy Distance Velocity Regular

12 12 Evaluation Metrics Delay The time to fill up the main road with a certain number of cars from the ramp Throughput The number of cars that complete merging over a period of time Flow The product of density and velocity

13 13 Simulation Intelligent Driver Model (IDM) Microscopic traffic model Safety distance ParameterValue Maximum velocity Safe time headway Maximum acceleration Maximum deceleration 100 km/h 1.5 s 1m/s^2 3m/s^2 Exit ramp

14 14 Experiments and Results Experiment settingsLight Medium HeavyUnit Main road Ramp 5 10 15 3.6 -- 7.2 cars/km

15 15 Experiments and Results

16 16 Summary Traffic merging strategies benefit from sensor- enabled cars Proactive merging algorithm outperforms regular strategy in terms of throughput and delay Achieved at the cost of slightly lower velocity

17 17 Robustness of Algorithms Human factors Imperfect information Sensor accuracy Unreliable communication medium Studies* show only 50-60% of cars in range will receive a cars broadcast Penetration rates Initially, only a small number of sensor-enabled cars * Source: J. Yin, T. EIBatt, and S. Habermas, Performance evaluation of safety applications over DSRC vehicular ad hoc networks, VANET 2004

18 18 Higher Degree of Realism Obstacles Blocking Traffic patterns Different distributions Multiple lanes Lane-changing Heterogeneity Different types of vehicles

19 19 Thank you! Questions, Suggestions, & Comments


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