scholarly journals Optimal coordination of variable speed limits to suppress shock waves

2004 ◽  
Author(s):  
A. Hegyi ◽  
B. De Schutter ◽  
H. Hellendoorn
Keyword(s):  
Shock Waves ◽  
Variable Speed ◽  
Speed Limits ◽  
Variable Speed Limits ◽  
Optimal Coordination

scholarly journals Optimal Coordination of Variable Speed Limits to Suppress Shock Waves

2003 ◽  
Vol 1852 (1) ◽  
pp. 167-174 ◽  
Author(s):  
A. Hegyi ◽  
B. De Schutter ◽  
J. Hellendoorn
Keyword(s):  
Shock Waves ◽  
Variable Speed ◽  
Highway Traffic ◽  
Speed Limits ◽  
Variable Speed Limits ◽  
Control Objective ◽  
Safety Constraints ◽  
Optimal Coordination ◽  
Safety Constraint ◽  
Discrete Controller

A model predictive control (MPC) approach is presented to optimally coordinate variable speed limits for highway traffic. A safety constraint incorporated in the controller is formulated that prevents drivers from encountering speed limit drops larger than, say, 10 km/h. The control objective is to minimize the total time that vehicles spend in the network. This approach results in dynamic speed limits that reduce or even eliminate shock waves. To predict the evolution of the traffic flows in the network, which is required by MPC, an adapted version of the METANET model is used that takes the variable speed limits into account. The performance of the discrete-valued and safety-constrained controllers is compared with the performance of the continuous-valued unconstrained controller. It is found that both types of controllers result in a network with less congestion, a higher outflow, and hence a lower total time spent for drivers. For the benchmark problem, the performance of the discrete controller with safety constraints is comparable with the continuous controller without constraints.

scholarly journals Homogenization Effects of Variable Speed Limits

2014 ◽  
Vol 15 (2) ◽  
pp. 130-143 ◽  
Author(s):  
Alvaro Garcia-Castro ◽  
Andres Monzon
Keyword(s):  
Weather Conditions ◽  
Variable Speed ◽  
Variable Speed Limit ◽  
Speed Limits ◽  
Key Indicator ◽  
Variable Speed Limits ◽  
Performance And Emissions ◽  
Speed Management ◽  
Road Performance

Abstract Changing factors (mainly traffic intensity and weather conditions) affecting road conditions require a suitable optimal speed at any time. To solve this problem, variable speed limit systems (VSL) - as opposed to fixed limits - have been developed in recent decades. This term has included a number of speed management systems, most notably dynamic speed limits (DSL). In order to avoid the indiscriminate use of both terms in the literature, this paper proposes a simple classification and offers a review of some experiences, how their effects are evaluated and their results This study also presents a key indicator which measures the speed homogeneity and a methodology to obtain the data based on floating cars and GPS technology applying it to a case study on a section of the M30 urban motorway in Madrid (Spain). It also presents the relation between this indicator and road performance and emissions values.

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

2016 ◽  
Vol 40 (3) ◽  
pp. 843-852 ◽  
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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