Motorway Tidal Flow Lane Control

A traffic control case of particular importance occurs when inbound and outbound traffic on a motorway stretch is unbalanced throughout the day. This scenario may benefit of a lane management strategy called tidal flow (or reversible) lane control, in which case the direction of a contraflow buffer lane is reversed according to the needs of each direction. This paper proposes a simple and practical real-time strategy for efficient motorway tidal flow lane control. A switching policy based on the fundamental diagram, that requires only aggregated measurements of density (or occupancy), is adopted. A kinematic wave theory-based traffic flow analysis shows that the proposed strategy provides a Pareto-optimal solution. Simulation studies of the A38(M) Aston Expressway (Birmingham, UK), are used to demonstrate its operation. The results confirm an increase of motorway throughput and a smooth operation of the strategy

Aplicação de maximização de largura de banda no controle de tráfego urbano em tempo-real

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Engenharia Elétrica.O módulo de controle de defasagem da estratégia Traffic-responsive Urban Control - TUC para controle em tempo-real de tráfego urbano é substituído por um método de maximização de largura de banda. A maximização de largura de banda é realizada em tempo-real, baseada nas mudanças das porcentagens de verde e do tempo de ciclo. Em vias arteriais é desejável, por operadores de tráfego e motoristas, uma boa progressão veicular. Técnicas de maximização de largura banda são largamente utilizadas em sistemas de planos a tempos fixos para favorecer a progressão veicular em vias arteriais. No controle em tempo-real a utilização destas técnicas não foi explorada. Simulações em uma via arterial com cinco interseções foram realizadas. Os resultados indicam que o desempenho desta estratégia é comparável com a estratégia de controle TUC e superior à estratégia de tempo fixo ajustada otimamente

Motorway tidal flow lane control

The expansion of road infrastructure, in spite of increasing congestion levels, faces severe restrictions from all sorts: economical, environmental, social, or technical. An efficient and, usually, less expensive alternative to improve mobility and the use of available infrastructure is the adoption of traffic management. A particular case of interest occurs when inbound and outbound traffic on a given facility is unbalanced throughout the day. This scenario may benefit of a lane management strategy called tidal flow (or reversible) lane control, in which case the direction of one or more contraflow buffer lanes is reversed according to the needs of each direction. This paper proposes a simple and practical real-time strategy for efficient motorway tidal flow lane control. A state-feedback switching policy based on the triangular fundamental diagram, that requires only aggregated measurements of density, is adopted. A theoretical analysis based on the kinematic wave theory shows that the strategy provides a Pareto-optimal solution. Microsimulations using empirical data from the A38(M) Aston Expressway in Birmingham, UK, are used to demonstrate the operation of the proposed strategy. The robustness of the switching policy to parameter variations is demonstrated by parametric sensitivity analysis. Simulation results confirm an increase of motorway throughput and a smooth operation for the simulated scenarios

Multi-commodity traffic signal control and routing with connected vehicles

A real-time traffic management policy that integrates traffic signal control and multi-commodity routing of connected vehicles in networks with multiple destinations is developed. The proposed policy is based on a multi-commodity formulation of the store-and-forward model and assumes all vehicles are able to exchange information with the infrastructure. Vehicles share information about their current location and final destination. Based on this information, the strategy determines both optimized signal timings at every intersection and vehicle-specific routing information at every link of the network. The control actions, i.e., signal times and routing information, are updated at every cycle and delivered by a finite horizon optimal control problem cast into a rolling horizon framework. The underlying optimization problem is convex, and thus the method is suitable for real-time operation in large networks. The method is validated via a micro-simulation study in networks with up to twenty intersections and, in all simulations, outperforms a real-time traffic-responsive signal control strategy that is based on a single-commodity store-and-forward model. The scalable computation effort for increasing network sizes and prediction horizon confirms the computational efficiency of the method

Calibração do modelo de consumo de combustível do simulador AIMSUN com dados coletados via OBD

Dados coletados por meio da interface de diagnóstico de bordo (On-Board Diagnostics ‒ OBD), presente nos automóveis nacionais fabricados a partir de 2009, foram usados na calibração de modelo microscópico de consumo de combustível do simulador AIMSUN. Para a calibração dos parâmetros do modelo de consumo, mediu-se a velocidade instantânea, o fluxo de ar de admissão e o teor de oxigênio na mistura ar/combustível. Calibrou-se o modelo de consumo do simulador seguindo a abordagem modal, usando regressão para os modos de aceleração e velocidades constantes e média simples para os modos de marcha lenta e desaceleração. Para validar o modelo, os consumos de combustível medido e estimado foram comparados em ciclos de condução em áreas urbanas. Os resultados indicam a adequação do método para avaliação do consumo de combustível por veículos em malhas viárias urbanas. Além disso, o modelo calibrado com dados do OBD de quatro tipos de veículos foi usado no estudo por simulação de cenários atual e futuro no contexto de projeto de ampliação viária. Por meio de abordagem comparativa entre cenários, mostra-se que a estimação com parâmetros calibrados produz indicadores distintos e mais confiáveis em relação aos obtidos com os parâmetros originais do simulador. 

Έλεγχος κύριας κυκλοφοριακής ροής αυτοκινητοδρόμων

The continuously increasing daily trac congestions on motorway networks around the world call for innovative control measures that would drastically improve the current trac conditions. Mainstream trac ow control (MTFC) is proposed as a novel and ecient motorway trac management tool, and its possible implementation and principal impact on trac ow eciency is analysed. Variable speed limits (VSLs), suitably operated and enforced, are considered as one (out of several possible) way(s) for MTFC realisation, either as a standalone measure or in combination with ramp metering. A quantitative model of the VSL impact on aggregate trac ow behaviour on motorways is proposed and allows for VSLs to be incorporated in a macroscopic second-order trac ow model as an additional control component. The integrated motorway network trac control problem involving ramp metering and VSLs is formulated as a constrained discrete-time optimal control problem and is solved eciently even for large-scale networks by a suitable feasible direction algorithm. An illustrative example of a hypothetical motorway stretch as well as a large-scale motorway ring-road are investigated under dierent control scenarios using the optimal control approach. It is shown that trac ow eciency can be substantially improved when MTFC via VSLs is used with or without integration with coordinated ramp metering actions. Since sophisticated optimal control methods may face diculties in practical eld implementations, three simple controllers for local feedback MTFC on motorways, enabled via VSLs, are proposed in this thesis. All feedback controllers rely only on readily available real-time measurements (no on-line model usage and no demand predictions are needed), take into account a number of practical and safety restrictions, and are therefore robust and suitable for eld implementations. The controllers are evaluated in simulation and compared with the optimal control results for a hypothetical motorway stretch. Despite their simplicity, the results show that the feedback controllers exhibit a satisfactory control behaviour and, indeed, approach the optimal control results for a number of investigated scenarios. Recommendations for the operation of the feedback controllers are given

Mainstream traffic flow control on motorways

Περίληψη: Μη διαθέσιμ

A Kinematic Wave Theory of Tidal Traffic Flow

This work presents a theoretical analysis of tidal traffic flow that is based on the Kinematic Wave Theory (KWT). Also it provides a number of insights on the effectiveness of tidal flow lane management in terms of motorway capacity, throughput maximisation, and total time spent. The main question this work addresses is: If inflows and outflows are balanced to maintain the bi-directional traffic in a steady-state for a fixed total number of desired bi-directional trips, what is the distribution of densities that maximises the bi-directional total outflow. How the infrastructure should be managed to accommodate this distribution? For the analysis of tidal traffic flow a simple kinematic wave model is employed that is based on a generic or a triangular fundamental diagram (FD). Two location-dependent concave FDs one for each direction of traffic are employed to discuss the kinematic wave solutions of the prevailing traffic

Optimal Control of Motorway Tidal Flow

When inbound and outbound traffic on a bi-directional motorway is unbalanced throughout the day a lane management strategy called tidal (reversible) flow lane control is usually applied. In this control case, the direction of one or more contraflow buffer lanes is reversed according to the needs of each direction. This paper introduces a basic dynamical model for tidal traffic flow and considers the minimum traveltime, minimum-time, and maximum throughput optimal control problems for efficient motorway tidal flow lane control. Lane management is effectuated by a control variable, indicating the number of lanes opened or closed in each direction of traffic. To derive the analytical form of optimal control, the Pontryagin's maximum principle is employed. The obtained optimal control is intuitively natural of bang-bang type, as also shown in a previous work by the authors [1]. It takes only the values ±1 and switches between these values at most once. In other words, the optimal control strategy consists of switching between opening and closing in each direction of traffic one contraflow buffer lane. Of course it is an open-loop control, and thus the switch time (if applicable) depends on the initial conditions. In the case of the maximum throughput optimal control problem, semi-state feedback control is obtained and singular arcs might exist. Finally, cumulative arrival rate and output curves for both directions of traffic are used to provide a graphical interpretation of the minimum travel-time optimal control problem and obtained bang-bang control

A Kinematic Wave Theory of Tidal Traffic Flow

This work presents a theoretical analysis of tidal traffic flow that is based on the Kinematic Wave Theory (KWT). Also it provides a number of insights on the effectiveness of tidal flow lane management in terms of motorway capacity, throughput maximisation, and total time spent. The main question this work addresses is: If inflows and outflows are balanced to maintain the bi-directional traffic in a steady-state for a fixed total number of desired bi-directional trips, what is the distribution of densities that maximises the bi-directional total outflow. How the infrastructure should be managed to accommodate this distribution? For the analysis of tidal traffic flow a simple kinematic wave model is employed that is based on a generic or a triangular fundamental diagram (FD). Two location-dependent concave FDs one for each direction of traffic are employed to discuss the kinematic wave solutions of the prevailing traffic