Jordi Casas | Universitat de Vic (original) (raw)

Papers by Jordi Casas

Incident detection is a key component in real-time traffic management systems that allows efficie... more Incident detection is a key component in real-time traffic management systems that allows efficient response plan generation and decision making by means of risk alerts at critical affected sections in the network. State-of-the-art incident detection techniques traditionally require: i) good quality data from closely located sensor pairs, ii) a minimum of two reliable measurements from the flow- occupancy-speed triad, and iii) supervised adjustment of thresholds that will trigger anomalous traffic states. Despite such requirements may be reasonably achieved in simulated scenarios, real-time downstream applications rarely work under such ideal conditions and must deal with low reliability data, missing measurements, and scarcity of curated incident labelled datasets, among other challenges. This paper proposes an unsupervised technique based on univariate timeseries anomaly detection for computationally efficient incident detection in real-world scenarios. Such technique is proved to successfully work when only flow measurements are available, and to dynamically adjust thresholds that adapt to changes in the supply. Moreover, results show good performance with low-reliability and missing data.

Zenodo (CERN European Organization for Nuclear Research), Sep 7, 2021

Due to the rapidly accelerated innovation cycle in transport and the emergence of new mobility co... more Due to the rapidly accelerated innovation cycle in transport and the emergence of new mobility concepts and technologies, public authorities, policy makers, and transport planners are currently in need of the tools for sustainable spatial and transport planning in the new mobility era. In this paper, a new modular, software-agnostic and activity-based spatial and transport planning platform is designed, i.e, the HARMONY Model Suite, that facilitates a novel integration of new and existing spatial and transport modelling tools. The paper focuses on describing the architecture of the platform and its passenger mobility simulation framework, which integrates -in an interoperable manner-activity-based models, mobility service management, and traffic simulation tools for evaluating new mobility system dynamics. The service management controllers for new mobility concepts are discussed in more detail with regards to their functionality and applicability.

United States. Federal Highway Administration, Jun 1, 2021

2017PDFTech ReportFHWA-HRT-18-012HRDO-20/12-2017(200)ERoad shouldersTraffic lanesUnited StatesUni... more 2017PDFTech ReportFHWA-HRT-18-012HRDO-20/12-2017(200)ERoad shouldersTraffic lanesUnited StatesUnited States. Federal Highway Administration. Office of Operations Research and DevelopmentUnited States. Federal Highway Administration. Office of Operations Research and DevelopmentTurner-Fairbank Highway Research CenterBared, Joe G.Federal Highway AdministrationEveryday traffic delays produce frustrations and wasted time for road users who frequently deal with delays, especially during commutes and rush hour trips. Innovative solutions are needed for near-term implementation. These solutions produce significant operational benefits with only minor modifications to existing infrastructure, using less time and resources to make major impacts on traffic delays.The Saxton Transportation Operations Lab (STOL), located at the Federal Highway Administration Turner-Fairbank Research Center in McLean, VA, is focused on one of these alternative solutions: the lane-width reduction strategy

This paper examines a metamodel-based technique for model sensitivity analysis and applies it to ... more This paper examines a metamodel-based technique for model sensitivity analysis and applies it to the Aimsun mesoscopic model. The paper argues that sensitivity analysis is crucial for the best use of the traffic simulation models while also acknowledging that the main obstacle to an extensive use of the most sophisticated techniques is the high number of model runs they usually require. To get around this problem, the paper considers the possibility of performing sensitivity analysis not on a model but on its metamodel approximation. Important issues arising when estimating a metamodel have been investigated and commented on in the specific application to the Aimsun model. Among these issues is the importance of selecting a proper sampling strategy based on low discrepancy random number sequences and the importance of selecting a class of metamodels able to reproduce the inputs-ouputs relationship in a robust and reliable way. Sobol sequences and Gaussian process metamodels have been recognized as the appropriate choices. The paper assesses the proposed methodology by comparing the results of the application of variancebased sensitivity analysis techniques to the simulation model and to a metamodel estimated with 512 model runs, on a variety of traffic scenarios and model outputs. Results confirm the powerfulness of the proposed methodology and also open up to a more extensive application of sensitivity analysis techniques to complex traffic simulation models.

Transportation Research Record, May 22, 2022

The paper proposes a general framework for the assessment of the impacts of the introduction of C... more The paper proposes a general framework for the assessment of the impacts of the introduction of Connected and Automated Transport Systems (CATS) on traffic. The main objective is to address the question of scalability and transferability of the identified impacts of Autonomous Vehicles (AVs) in particular, focusing on network performance of urban areas. A combination of microscopic and macroscopic simulations as well as statistical methods are applied. Microscopic simulation is conducted to measure the changes in network capacities by utilizing the concept of the Macroscopic Fundamental Diagram (MFD), under different AV penetration rates. The resulting capacities are used to estimate the effects on the Passenger Car Units (PCU) under different AV penetration rates and derive functional relationships, which are further introduced to travel demand models to forecast the macroscopic impacts on network performance. The results indicate a positive impact in relation to capacity changes resulting from the presence of AVs which vary with penetration rate. Analysis of three different urban networks, Barcelona, Bilbao (Spain), and Athens (Greece), reveals consistent trends. However, notable differences are observed on the estimated PCUs for Athens, potentially because of the different mixed-traffic composition. Further exploration of the critical AV modeling specifications and network characteristics is therefore required for deriving transferable PCU functional relationships across networks. Nevertheless, the static assignment results verify the expected trends in network performance impacts in relation to the applied PCU relationships. Finally, the transferability of the proposed methodology across networks is demonstrated.

IFAC Proceedings Volumes, 1997

Modem Traffic Management Systems provide the traffic engineer with the information on current and... more Modem Traffic Management Systems provide the traffic engineer with the information on current and forecasted traffic conditions, traffic conflicts, etc., required to support a rational decision making process. That information is the outcome of a computing process whose inputs are the raw traffic data supplied in real-time by various data sources, and whose components are complex algorithmic procedures implementing numerically models for dynamic traffic assignment, OlD estimation, traffic simulation, etc., which imply a heavy computational overhead. This paper describes the architecture, the parallel approach taken in developing a prototype of such a system, its implementation on a shared memory environment, and the preliminary results of testing the system on Barcelona's Ring Roads.

This article looks at three situations common to traffic projects and how the GETRAM supporting s... more This article looks at three situations common to traffic projects and how the GETRAM supporting software modelling platform. It discusses how microsimulation tools need to be able to provide route updates assign routes to vehicles, and dynamically reroute vehicles when needed.

Following terrible accidents in recent years in tunnels in the Alps efforts to manage traffic mor... more Following terrible accidents in recent years in tunnels in the Alps efforts to manage traffic more safely has yielded two areas of traffic management and monitoring strategies. The first concentrates on reducing the number of accidents by inaugurating preventive safety measures; the other looks to tracking heavy vehicles and forcing them to keep safe distances. This article describes a method for avoiding platoons of trucks traveling in opposite directions through the tunnel at the same time. It is being implemented in the Saint Gothard tunnel and the Vielha tunnel in the Pyrenees between France and Spain.

Dynamic guidance systems accounting for real-time and predicted traffic conditions are still unde... more Dynamic guidance systems accounting for real-time and predicted traffic conditions are still under experimentation and, although most of the research seems to show that potential benefits, for the user as well as for the whole traffic system, are to be expected from guidance, still remain many unclear aspects that should be investigated. Microscopic simulation appears as perhaps the most suitable tool to analyze dynamic guidance systems, combining the ability to capture the full dynamics of the time dependent traffic phenomena with the capability to track individual vehicles. This paper presents and discusses the simulation results for a real urban network with the AIMSUN2 microsimulator. The simulation experiments analyze the expected benefits depending on the quality of the used routes. (A*) For the covering abstract see ITRD E110327.

… Future. Abstracts of the …, 1996

Abstract: Modern Traffic Management Systems provide the traffic engineer with information on curr... more Abstract: Modern Traffic Management Systems provide the traffic engineer with information on current and forecasted traffic conditions, traffic conflicts, etc., required to support a rational decision making process. That information is the outcome of a computing process whose ...

Two system architectures for traffic management are proposed in this paper. Both are based on the... more Two system architectures for traffic management are proposed in this paper. Both are based on the concept of decision support system, and propose decision support systems for traffic management for two types of situations: a road network managed by a unique traffic control centre, and an area, possibly a metropolitan one, subdivided in zones each one under the control of a different traffic control centre with possibly different control strategies, that would require a certain level of coordination to improve the performance of the whole system. The proposed architectures are based on a short term demand forecasting and a microscopic simulator to estimate network states, current and forecast. The paper mainly discusses the role of the microscopic simulation, its computing performance for real-time applications when parallelization is taken into account, and briefly discusses some preliminary results on the system validation. (a) For the covering entry of this conference, please see IRRD abstract no. 492019.

IEEE Transactions on Intelligent Transportation Systems

The evaluation of advanced traffic signal systems requires a network-wide assessment of their imp... more The evaluation of advanced traffic signal systems requires a network-wide assessment of their impact as opposed to an isolated analysis of key intersections. Microscopic traffic simulation models emulate the dynamics of individual vehicles in a detailed network representation, based on car-following, lane changing, gap acceptance models; include route choice models to implement dynamic traffic assignment; and account explicitly for traffic control. Microscopic models are usually appropriate for operational analysis due the detail of information provided by the simulator. However, they are data intensive and have a significant computational cost. Mesoscopic models combine simplified flow dynamics with explicit treatment of interrupted flows at intersections and allow modeling of large networks with high computational efficiency. However, the loss of realism implied by a mesoscopic model makes it necessary to emulate detailed outputs; for instance, detector measurements or instantaneo...

Gap acceptance theory has traditionally been the basis for calculations on roundabout and unsigna... more Gap acceptance theory has traditionally been the basis for calculations on roundabout and unsignalized intersection performance. However, when queue spillbacks from a downstream bottleneck propagate through the intersection, gap acceptance theory does not always apply in practice. Modelling areas with heavy congestion is usually more important than modelling areas without congestion. Nevertheless, oversaturation, queue spillbacks and network effects make modelling more complicated. This paper demonstrates a new method for simulating oversaturated unsignalized intersections and roundabouts; the Turn Cooperation Model Activation (TCMA). Field observations at three roundabouts and one unsignalized intersection in Trondheim and Bergen (Norway) confirm that the interaction between drivers in severely oversaturated conditions may deviate from priority rules and gap acceptance theory. The TCMA enables the user to model cooperation between drivers. In all four intersections, simulations wit...

IFAC Proceedings Volumes, 2006

Two simulation approaches to emulate traffic flow dynamics are mesoscopic modeling which combines... more Two simulation approaches to emulate traffic flow dynamics are mesoscopic modeling which combines aspects of flow theory with explicit treatment of interrupted flows at intersections and allows modeling large networks with high computational efficiency dealing with dynamics aspects in strategic planning and microscopic approaches modeling the individual dynamics of each vehicle by means of car-following, lane changing and other models consistent with traffic flow theory with higher computational cost but allowing a very detailed analysis appropriated for operational planning. Combining meso and micro is methodologically appealing but raises consistency problems on the network representation and the transitions meso-micro-meso. This paper discusses these problems, proposes a solution and illustrates how it works in practice.

One of the essential quantities in macro traffic simulation is the ‘who goes where’ OD matrix. Th... more One of the essential quantities in macro traffic simulation is the ‘who goes where’ OD matrix. This is usually estimated through an optimization problem of minimizing the squared differences between observed and simulated traffic counts. The choice of the mean square error loss is due to its good statistical properties and the fact that the related quadratic optimization problem is easy to deal with. However, in many applications following the recommendations of validation criteria suggested in many guidelines published by different road administrations, such as FHWA in USA, ARRB in Australia or Highways Agency in UK, the quality of a static OD adjustment is assessed with other quantities such as the relative error or the GEH index. A direct minimization of the GEH index involves technical difficulties. However, recent developments in optimization theory give the opportunity of solving such problem using gradient descent techniques. We apply this method to some static OD estimation ...

This paper underlines the importance to adequately combine the different type of modeling level f... more This paper underlines the importance to adequately combine the different type of modeling level for assessing ITS applications instead of making them compete one versus each other. Indeed, each level offers certain advantages or allows getting certain outputs that others can’t, many time the output of one being the input of another one. Based on this statement, the present paper presents the idea of an integrated environment to facilitate this combination and demonstrate it with a set of show cases.

Macro, meso and micro approaches have traditionally grown up independently to provide answers to ... more Macro, meso and micro approaches have traditionally grown up independently to provide answers to specific problems in traffic and transportation analysis, however, a proper analysis of complex networks, as in the case of corridor analysis, asks for an integrated combination of the three approaches. Macro travel demand models are usually based on the user equilibrium and are static in nature, while simulation approaches emulate traffic flow dynamics. Mesoscopic approaches are based on simplified flow models with explicit treatment of intersections and allow modeling large networks with high computational efficiency adding the dynamic dimension to strategic planning. Microscopic approaches modeling the individual dynamics of each vehicle by means of car-following, lane changing and other models, consistent with traffic flow theory, incur in higher computational costs but allow a very detailed analysis appropriated for operational planning. A methodology combining macro, meso and micro raises consistency problems on the network representation, the time dependent paths and on achieving dynamic user equilibrium. This paper discusses these problems, proposes a solution based on a combination of computer and traffic modeling and presents computational results to check experimentally the consistency of meso and micro models.

PETRI (Parallel Environment for a Real-Time Traffic Management and Information Systems) es el acr... more PETRI (Parallel Environment for a Real-Time Traffic Management and Information Systems) es el acronimo de un subproyecto del programa ESPIRIT de la Union Europea. Este sistema combina la experiencia en el desarrollo de sistemas de gestion e informacion de trafico con la del procesamiento informatico en paralelo. Se expone detalladamente la estructura conceptual del sistema: la secuencia temporal de las actividades, la estimacion dinamica de la matriz origen-destino y la carga dinamica de la red. Desde el punto de vista de la modelizacion, el simulador microscopico AIMSUN2 (Advanced Interactive Microscopic Simulator for Urban and Non-Urban Networks), representa el comportamiento de los flujos de la red de trafico. La integracion de las funciones propuestas se realiza en el marco de un sistema de ayuda a la toma de decisiones, con la estructura informatica mas eficiente que permite tratar la informacion, presentarla al operador y proponerle un abanico de actuaciones en tiempo casi real.

Incident detection is a key component in real-time traffic management systems that allows efficie... more Incident detection is a key component in real-time traffic management systems that allows efficient response plan generation and decision making by means of risk alerts at critical affected sections in the network. State-of-the-art incident detection techniques traditionally require: i) good quality data from closely located sensor pairs, ii) a minimum of two reliable measurements from the flow- occupancy-speed triad, and iii) supervised adjustment of thresholds that will trigger anomalous traffic states. Despite such requirements may be reasonably achieved in simulated scenarios, real-time downstream applications rarely work under such ideal conditions and must deal with low reliability data, missing measurements, and scarcity of curated incident labelled datasets, among other challenges. This paper proposes an unsupervised technique based on univariate timeseries anomaly detection for computationally efficient incident detection in real-world scenarios. Such technique is proved to successfully work when only flow measurements are available, and to dynamically adjust thresholds that adapt to changes in the supply. Moreover, results show good performance with low-reliability and missing data.

Zenodo (CERN European Organization for Nuclear Research), Sep 7, 2021

Due to the rapidly accelerated innovation cycle in transport and the emergence of new mobility co... more Due to the rapidly accelerated innovation cycle in transport and the emergence of new mobility concepts and technologies, public authorities, policy makers, and transport planners are currently in need of the tools for sustainable spatial and transport planning in the new mobility era. In this paper, a new modular, software-agnostic and activity-based spatial and transport planning platform is designed, i.e, the HARMONY Model Suite, that facilitates a novel integration of new and existing spatial and transport modelling tools. The paper focuses on describing the architecture of the platform and its passenger mobility simulation framework, which integrates -in an interoperable manner-activity-based models, mobility service management, and traffic simulation tools for evaluating new mobility system dynamics. The service management controllers for new mobility concepts are discussed in more detail with regards to their functionality and applicability.

United States. Federal Highway Administration, Jun 1, 2021

2017PDFTech ReportFHWA-HRT-18-012HRDO-20/12-2017(200)ERoad shouldersTraffic lanesUnited StatesUni... more 2017PDFTech ReportFHWA-HRT-18-012HRDO-20/12-2017(200)ERoad shouldersTraffic lanesUnited StatesUnited States. Federal Highway Administration. Office of Operations Research and DevelopmentUnited States. Federal Highway Administration. Office of Operations Research and DevelopmentTurner-Fairbank Highway Research CenterBared, Joe G.Federal Highway AdministrationEveryday traffic delays produce frustrations and wasted time for road users who frequently deal with delays, especially during commutes and rush hour trips. Innovative solutions are needed for near-term implementation. These solutions produce significant operational benefits with only minor modifications to existing infrastructure, using less time and resources to make major impacts on traffic delays.The Saxton Transportation Operations Lab (STOL), located at the Federal Highway Administration Turner-Fairbank Research Center in McLean, VA, is focused on one of these alternative solutions: the lane-width reduction strategy

This paper examines a metamodel-based technique for model sensitivity analysis and applies it to ... more This paper examines a metamodel-based technique for model sensitivity analysis and applies it to the Aimsun mesoscopic model. The paper argues that sensitivity analysis is crucial for the best use of the traffic simulation models while also acknowledging that the main obstacle to an extensive use of the most sophisticated techniques is the high number of model runs they usually require. To get around this problem, the paper considers the possibility of performing sensitivity analysis not on a model but on its metamodel approximation. Important issues arising when estimating a metamodel have been investigated and commented on in the specific application to the Aimsun model. Among these issues is the importance of selecting a proper sampling strategy based on low discrepancy random number sequences and the importance of selecting a class of metamodels able to reproduce the inputs-ouputs relationship in a robust and reliable way. Sobol sequences and Gaussian process metamodels have been recognized as the appropriate choices. The paper assesses the proposed methodology by comparing the results of the application of variancebased sensitivity analysis techniques to the simulation model and to a metamodel estimated with 512 model runs, on a variety of traffic scenarios and model outputs. Results confirm the powerfulness of the proposed methodology and also open up to a more extensive application of sensitivity analysis techniques to complex traffic simulation models.

Transportation Research Record, May 22, 2022

The paper proposes a general framework for the assessment of the impacts of the introduction of C... more The paper proposes a general framework for the assessment of the impacts of the introduction of Connected and Automated Transport Systems (CATS) on traffic. The main objective is to address the question of scalability and transferability of the identified impacts of Autonomous Vehicles (AVs) in particular, focusing on network performance of urban areas. A combination of microscopic and macroscopic simulations as well as statistical methods are applied. Microscopic simulation is conducted to measure the changes in network capacities by utilizing the concept of the Macroscopic Fundamental Diagram (MFD), under different AV penetration rates. The resulting capacities are used to estimate the effects on the Passenger Car Units (PCU) under different AV penetration rates and derive functional relationships, which are further introduced to travel demand models to forecast the macroscopic impacts on network performance. The results indicate a positive impact in relation to capacity changes resulting from the presence of AVs which vary with penetration rate. Analysis of three different urban networks, Barcelona, Bilbao (Spain), and Athens (Greece), reveals consistent trends. However, notable differences are observed on the estimated PCUs for Athens, potentially because of the different mixed-traffic composition. Further exploration of the critical AV modeling specifications and network characteristics is therefore required for deriving transferable PCU functional relationships across networks. Nevertheless, the static assignment results verify the expected trends in network performance impacts in relation to the applied PCU relationships. Finally, the transferability of the proposed methodology across networks is demonstrated.

IFAC Proceedings Volumes, 1997

Modem Traffic Management Systems provide the traffic engineer with the information on current and... more Modem Traffic Management Systems provide the traffic engineer with the information on current and forecasted traffic conditions, traffic conflicts, etc., required to support a rational decision making process. That information is the outcome of a computing process whose inputs are the raw traffic data supplied in real-time by various data sources, and whose components are complex algorithmic procedures implementing numerically models for dynamic traffic assignment, OlD estimation, traffic simulation, etc., which imply a heavy computational overhead. This paper describes the architecture, the parallel approach taken in developing a prototype of such a system, its implementation on a shared memory environment, and the preliminary results of testing the system on Barcelona's Ring Roads.

This article looks at three situations common to traffic projects and how the GETRAM supporting s... more This article looks at three situations common to traffic projects and how the GETRAM supporting software modelling platform. It discusses how microsimulation tools need to be able to provide route updates assign routes to vehicles, and dynamically reroute vehicles when needed.

Following terrible accidents in recent years in tunnels in the Alps efforts to manage traffic mor... more Following terrible accidents in recent years in tunnels in the Alps efforts to manage traffic more safely has yielded two areas of traffic management and monitoring strategies. The first concentrates on reducing the number of accidents by inaugurating preventive safety measures; the other looks to tracking heavy vehicles and forcing them to keep safe distances. This article describes a method for avoiding platoons of trucks traveling in opposite directions through the tunnel at the same time. It is being implemented in the Saint Gothard tunnel and the Vielha tunnel in the Pyrenees between France and Spain.

Dynamic guidance systems accounting for real-time and predicted traffic conditions are still unde... more Dynamic guidance systems accounting for real-time and predicted traffic conditions are still under experimentation and, although most of the research seems to show that potential benefits, for the user as well as for the whole traffic system, are to be expected from guidance, still remain many unclear aspects that should be investigated. Microscopic simulation appears as perhaps the most suitable tool to analyze dynamic guidance systems, combining the ability to capture the full dynamics of the time dependent traffic phenomena with the capability to track individual vehicles. This paper presents and discusses the simulation results for a real urban network with the AIMSUN2 microsimulator. The simulation experiments analyze the expected benefits depending on the quality of the used routes. (A*) For the covering abstract see ITRD E110327.

… Future. Abstracts of the …, 1996

Abstract: Modern Traffic Management Systems provide the traffic engineer with information on curr... more Abstract: Modern Traffic Management Systems provide the traffic engineer with information on current and forecasted traffic conditions, traffic conflicts, etc., required to support a rational decision making process. That information is the outcome of a computing process whose ...

Two system architectures for traffic management are proposed in this paper. Both are based on the... more Two system architectures for traffic management are proposed in this paper. Both are based on the concept of decision support system, and propose decision support systems for traffic management for two types of situations: a road network managed by a unique traffic control centre, and an area, possibly a metropolitan one, subdivided in zones each one under the control of a different traffic control centre with possibly different control strategies, that would require a certain level of coordination to improve the performance of the whole system. The proposed architectures are based on a short term demand forecasting and a microscopic simulator to estimate network states, current and forecast. The paper mainly discusses the role of the microscopic simulation, its computing performance for real-time applications when parallelization is taken into account, and briefly discusses some preliminary results on the system validation. (a) For the covering entry of this conference, please see IRRD abstract no. 492019.

IEEE Transactions on Intelligent Transportation Systems

The evaluation of advanced traffic signal systems requires a network-wide assessment of their imp... more The evaluation of advanced traffic signal systems requires a network-wide assessment of their impact as opposed to an isolated analysis of key intersections. Microscopic traffic simulation models emulate the dynamics of individual vehicles in a detailed network representation, based on car-following, lane changing, gap acceptance models; include route choice models to implement dynamic traffic assignment; and account explicitly for traffic control. Microscopic models are usually appropriate for operational analysis due the detail of information provided by the simulator. However, they are data intensive and have a significant computational cost. Mesoscopic models combine simplified flow dynamics with explicit treatment of interrupted flows at intersections and allow modeling of large networks with high computational efficiency. However, the loss of realism implied by a mesoscopic model makes it necessary to emulate detailed outputs; for instance, detector measurements or instantaneo...

Gap acceptance theory has traditionally been the basis for calculations on roundabout and unsigna... more Gap acceptance theory has traditionally been the basis for calculations on roundabout and unsignalized intersection performance. However, when queue spillbacks from a downstream bottleneck propagate through the intersection, gap acceptance theory does not always apply in practice. Modelling areas with heavy congestion is usually more important than modelling areas without congestion. Nevertheless, oversaturation, queue spillbacks and network effects make modelling more complicated. This paper demonstrates a new method for simulating oversaturated unsignalized intersections and roundabouts; the Turn Cooperation Model Activation (TCMA). Field observations at three roundabouts and one unsignalized intersection in Trondheim and Bergen (Norway) confirm that the interaction between drivers in severely oversaturated conditions may deviate from priority rules and gap acceptance theory. The TCMA enables the user to model cooperation between drivers. In all four intersections, simulations wit...

IFAC Proceedings Volumes, 2006

Two simulation approaches to emulate traffic flow dynamics are mesoscopic modeling which combines... more Two simulation approaches to emulate traffic flow dynamics are mesoscopic modeling which combines aspects of flow theory with explicit treatment of interrupted flows at intersections and allows modeling large networks with high computational efficiency dealing with dynamics aspects in strategic planning and microscopic approaches modeling the individual dynamics of each vehicle by means of car-following, lane changing and other models consistent with traffic flow theory with higher computational cost but allowing a very detailed analysis appropriated for operational planning. Combining meso and micro is methodologically appealing but raises consistency problems on the network representation and the transitions meso-micro-meso. This paper discusses these problems, proposes a solution and illustrates how it works in practice.

One of the essential quantities in macro traffic simulation is the ‘who goes where’ OD matrix. Th... more One of the essential quantities in macro traffic simulation is the ‘who goes where’ OD matrix. This is usually estimated through an optimization problem of minimizing the squared differences between observed and simulated traffic counts. The choice of the mean square error loss is due to its good statistical properties and the fact that the related quadratic optimization problem is easy to deal with. However, in many applications following the recommendations of validation criteria suggested in many guidelines published by different road administrations, such as FHWA in USA, ARRB in Australia or Highways Agency in UK, the quality of a static OD adjustment is assessed with other quantities such as the relative error or the GEH index. A direct minimization of the GEH index involves technical difficulties. However, recent developments in optimization theory give the opportunity of solving such problem using gradient descent techniques. We apply this method to some static OD estimation ...

This paper underlines the importance to adequately combine the different type of modeling level f... more This paper underlines the importance to adequately combine the different type of modeling level for assessing ITS applications instead of making them compete one versus each other. Indeed, each level offers certain advantages or allows getting certain outputs that others can’t, many time the output of one being the input of another one. Based on this statement, the present paper presents the idea of an integrated environment to facilitate this combination and demonstrate it with a set of show cases.

Macro, meso and micro approaches have traditionally grown up independently to provide answers to ... more Macro, meso and micro approaches have traditionally grown up independently to provide answers to specific problems in traffic and transportation analysis, however, a proper analysis of complex networks, as in the case of corridor analysis, asks for an integrated combination of the three approaches. Macro travel demand models are usually based on the user equilibrium and are static in nature, while simulation approaches emulate traffic flow dynamics. Mesoscopic approaches are based on simplified flow models with explicit treatment of intersections and allow modeling large networks with high computational efficiency adding the dynamic dimension to strategic planning. Microscopic approaches modeling the individual dynamics of each vehicle by means of car-following, lane changing and other models, consistent with traffic flow theory, incur in higher computational costs but allow a very detailed analysis appropriated for operational planning. A methodology combining macro, meso and micro raises consistency problems on the network representation, the time dependent paths and on achieving dynamic user equilibrium. This paper discusses these problems, proposes a solution based on a combination of computer and traffic modeling and presents computational results to check experimentally the consistency of meso and micro models.

PETRI (Parallel Environment for a Real-Time Traffic Management and Information Systems) es el acr... more PETRI (Parallel Environment for a Real-Time Traffic Management and Information Systems) es el acronimo de un subproyecto del programa ESPIRIT de la Union Europea. Este sistema combina la experiencia en el desarrollo de sistemas de gestion e informacion de trafico con la del procesamiento informatico en paralelo. Se expone detalladamente la estructura conceptual del sistema: la secuencia temporal de las actividades, la estimacion dinamica de la matriz origen-destino y la carga dinamica de la red. Desde el punto de vista de la modelizacion, el simulador microscopico AIMSUN2 (Advanced Interactive Microscopic Simulator for Urban and Non-Urban Networks), representa el comportamiento de los flujos de la red de trafico. La integracion de las funciones propuestas se realiza en el marco de un sistema de ayuda a la toma de decisiones, con la estructura informatica mas eficiente que permite tratar la informacion, presentarla al operador y proponerle un abanico de actuaciones en tiempo casi real.