Flatness Based Control of Traffic Flow for Coordination of Ramp Metering and Variable Speed Limits

To enhance the efficiency of the existing freeway system and therefore to mitigate traffic congestion and related problems on the freeway mainline lane-drop bottleneck region, the advanced strategy for bottleneck control is essential. This paper proposes a method that integrates variable speed limits and ramp metering for freeway bottleneck region control to relieve the chaos in bottleneck region. To this end, based on the analyses of spatial-temporal patterns of traffic flow, a macroscopic traffic flow model is extended to describe the traffic flow operating characteristic by considering the impacts of variable speed limits in mainstream bottleneck region. In addition, to achieve the goal of balancing the priority of the vehicles on mainline and on-ramp, increasing capacity, and reducing travel delay on bottleneck region, an improved control model, as well as an advanced control strategy that integrates variable speed limits and ramp metering, is developed. The proposed method is tested in simulation for a real freeway infrastructure feed and calibrates real traffic variables. The results demonstrate that the proposed method can substantially improve the traffic flow efficiency of mainline and on-ramp and enhance the quality of traffic flow at the investigated freeway mainline bottleneck.

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Model predictive control for optimal coordination of ramp metering and variable speed limits

Transportation Research Part C Emerging Technologies ◽

10.1016/j.trc.2004.08.001 ◽

2005 ◽

Vol 13 (3) ◽

pp. 185-209 ◽

Cited By ~ 339

Author(s):

Andreas Hegyi ◽

Bart De Schutter ◽

Hans Hellendoorn

Keyword(s):

Model Predictive Control ◽

Predictive Control ◽

Ramp Metering ◽

Variable Speed ◽

Speed Limits ◽

Variable Speed Limits ◽

Optimal Coordination

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An integrated control method based on the priority of ways in a freeway network

Transactions of the Institute of Measurement and Control ◽

10.1177/0142331216668393 ◽

2016 ◽

Vol 40 (3) ◽

pp. 843-852 ◽

Cited By ~ 4

Author(s):

Minghui Ma ◽

Shidong Liang

Keyword(s):

Traffic Congestion ◽

Control Method ◽

Integrated Control ◽

Adaptive Controller ◽

Ramp Metering ◽

Traffic Density ◽

Variable Speed ◽

Speed Limits ◽

Variable Speed Limits ◽

Freeway Networks

Traffic congestion is a common problem in merging regions of freeway networks. An adaptive integrated control method involving variable speed limits and ramp metering is presented with the aim of easing traffic congestion at merging regions. The problem of the imbalanced rights of ways of the upstream mainline and on-ramp at the merging region is solved by constructing the evaluation indices of congestion degree. Specifically, the traffic density and queue length of the upstream mainline and on-ramp are selected for use in the evaluation indices. Then, an adaptive controller is designed, integrating variable speed limits and ramp metering. The proposed method is tested in simulations considering a real freeway network in China calibrated by real traffic variables. The results show that the proposed adaptive integrated control method can prevent traffic flow breakdown and maintain a high outflow at the merging region during peak periods. The adaptive integrated control may lead to a 17% improvement in traffic delay.

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