Traffic modeling, estimation and control for large-scale congested urban networks

Part I of the thesis investigates novel urban traffic state estimation methods utilizing probe vehicle data. Chapter 2 proposes a method to integrate the collective effect of dispersed probe data with traffic kinematic wave theory and data mining techniques to model the spatial and temporal dynamics of queue formation and dissipation in arterials. The queue estimation method captures interdependencies in queue evolutions of successive intersections, and moreover, the method is applicable in oversaturated conditions and includes a queue spillover statistical inference procedure. Chapter 3 develops a travel time reliability model to estimate arterial route travel times distribution (TTD) considering spatial and temporal correlations between traffic states in consecutive links. The model uses link-level travel time data and a heuristic grid clustering method to estimate the state structure and transition probabilities of a Markov chain. By applying the Markov chain procedure, the correlation between states of successive links is integrated and the route-level TTD is estimated. The methods in Part I are tested with various probe vehicle penetration rates on case studies with field measurements and simulated data. The methods are straightforward in implementation and have demonstrated promising performance and accuracy through numerous experiments. Part II studies network-level modeling and control of large-scale urban networks. Chapter 4 is the pioneer that introduces the urban perimeter control for two-region urban cities as an elegant control strategy to decrease delays in urban networks. Perimeter controllers operate on the border between the two regions, and manipulate the percentages of transfer flows between the two regions, such that the number of trips reaching their destinations is maximized. The optimal perimeter control problem is solved by the model predictive control (MPC) scheme, where the prediction model and the plant (reality) are formulated by macroscopic fundamental diagrams (MFD). Chapter 5 extends the perimeter control strategy and MFD modeling to mixed urban-freeway networks to provide a holistic approach for large-scale integrated corridor management (ICM). The network consists of two urban regions, each one with a well-defined MFD, and a freeway, modeled by the asymmetric cell transmission model, that is an alternative commuting route which has one on-ramp and one off-ramp within each urban region. The optimal traffic control problem is solved by the MPC approach to minimize total delay in the entire network considering several control policies with different levels of urban-freeway control coordination. Chapter 6 integrates traffic heterogeneity dynamics in large-scale urban modeling and control to develop a hierarchical control strategy for heterogeneously congested cities. Two aggregated models, region- and subregion-based MFDs, are introduced to study the effect of link density heterogeneity on the scatter and hysteresis of MFD. A hierarchical perimeter flow control problem is proposed to minimize the network delay and to homogenize the distribution of congestion. The first level of the hierarchical control problem is solved by the MPC approach, where the prediction model is the aggregated parsimonious region-based MFD and the plant is the subregion-based MFD, which is a more detailed model. At the lower level, a feedback controller tries to maximize the network outflow, by increasing regional homogeneity

2nd Symposium on Management of Future motorway and urban Traffic Systems (MFTS 2018): Booklet of abstracts: Ispra, 11-12 June 2018

The Symposium focuses on future traffic management systems, covering the subjects of traffic control, estimation, and modelling of motorway and urban networks, with particular emphasis on the presence of advanced vehicle communication and automation technologies. As connectivity and automation are being progressively introduced in our transport and mobility systems, there is indeed a growing need to understand the implications and opportunities for an enhanced traffic management as well as to identify innovative ways and tools to optimise traffic efficiency. In particular the debate on centralised versus decentralised traffic management in the presence of connected and automated vehicles has started attracting the attention of the research community. In this context, the Symposium provides a remarkable opportunity to share novel ideas and discuss future research directions.JRC.C.4-Sustainable Transpor

Efficient freeway MPC by parameterization of ALINEA and a speed-limited area

Freeway congestion can reduce the freeway throughput due to the capacity drop or due to blocking caused by spillback to upstream ramps. Research has shown that congestion can be reduced by the application of ramp metering and variable speed limits. Model predictive control is a promising strategy for the optimization of the ramp metering rates and variable speed limits to improve the freeway throughput. However, several challenges have to be addressed before it can be applied for the control of freeway traffic. This paper focuses on the challenge of reducing the computation time of MPC strategies for the integration of variable speed limits and ramp metering. This is realized via a parameterized control strategy that optimizes the upstream and downstream boundaries of a speed-limited area and the parameters of the ALINEA ramp metering strategy. Due to the parameterization, the solution space reduces substantially, leading to an improved computation time. More specifically, the number of optimization variables for the variable speed limit strategy becomes independent of the number of variable message signs, and the number of optimization variables for the ramp metering strategy becomes independent of the prediction horizon. The control strategy is evaluated with a macroscopic model of a two-lane freeway with two ON-ramps and OFF-ramps. It is shown that parameterization realizes improved throughput when compared with a non-parameterized strategy when using the same amount of computation time.Transport and PlanningTransport and PlanningDelft Center for Systems and ControlTeam DeSchutte

Criticism in the absence of criticism

English abstract: Criticism is defined as the examination and judgment about someone or something. This definition includes, at first, an analytical task -with a particular methodology related to it- and, at second, a synthetic activity, translated into a value judgment on what is previously analyzed. Criticism can be done in different ways and depths: from the basic critical thinking -essentially descriptive- to the most truthful one –the poetic criticism-, that transcends pure description or analysis and refers itself to the internal coherence of the object. Any criticism that seeks to reduce the distance to the truth will address both to the intrinsic object relationships -or own laws- and to the extrinsic ones. Furthermore, an objective criticism provides a knowledge of the object regardless of the observer or frame of reference. This provides an effective method and a guaranteed way to approach to the knowledge of the object. Does this mean that without a regular critical method no criticism is undertaken? The proposal of this paper is to explain how a critical thought can be undertaken in the absence of criticism, in which there is no explicit value judgment. Taking the hypothesis that there is criticism in the absence of criticism, an architectural work –either being a building, a writing on architecture, etc.- that implies a tacit criticism could work on two levels: as a practical result –built, literary, etc.- and as a critical thought. The hypothesis proposes that such duality, criticism and practice, may come together in a single work. Although not in any. The existence of criticism in the absence of criticism will depend on the nature of the object and, with no doubt, on the speaker and receiver. At first glance, the guarantees provided by this criticism in the absence of criticism seem less tan through the orthodox one, in which the subject is the weakest part of the chain. However, the absence of explicit value judgment can lead to a series of stimuli –coherency, aesthetic, recreational or other- that, in certain contexts, do more viable the approach to the knowledge than through the conventional method. Spanish abstract: La crítica se define como el examen y juicio acerca de alguien o algo. Esta definición comprende, por un lado, una tarea analítica -con una determinada metodología asociada- y, por otro, una actividad sintética, traducida en un juicio de valor acerca de lo previamente analizado. La crítica puede hacerse de distinta forma y con distinto grado de profundidad: desde la más básica –fundamentalmente, la crítica descriptiva- hasta la más veraz -la crítica poética-, que trasciende la descripción o el análi sis puro y se refiere a la coherencia interna del objeto de estudio. Toda crítica que pretenda reducir la distancia de aproximación a la verdad se ocupará tanto de las relaciones intrínsecas o leyes propias del objeto como de las eelaciones extrínsecas al mismo. Por otro lado, una crítica objetiva facilita el conocimiento del objeto de estudio independientemente del observador o del marco de referencia, lo que la convierte en un método eficaz y con garantías para la aproximación al conocimiento del objeto. Pero ¿significa esto que sin crítica ortodoxa no puede existir crítica?. La propuesta de esta comunicación es dilucidar hasta qué punto puede emprenderse una crítica en ausencia de crítica, es decir, una crítica en la que no sea explícito el juicio de valor. Tomando como hipótesis el hecho de que exista crítica en ausencia de crítica, una obra arquitectónica –ya sea un edificio construido, un escrito sobre arquitectura, etc.- que implique una crítica tácita podría funcionar a dos niveles: como producto práctico -edificado, literario, etc.- y como reflexión crítica. La hipótesis planteada propone que tal dualidad, la crítica y la práctica, pueda confluir en una misma obra. Aunque no en cualquiera. La existencia de crítica en ausencia de crítica dependerá de la naturaleza de la obra y, sin lugar a dudas, del emisor y el receptor del mensaje crítico. A primera vista, las garantías que ofrece la crítica en ausencia de crítica parecen menores que mediante la crítica ortodoxa, para la que el sujeto es la parte más débil de la cadena. Sin embargo, la ausencia de juicio de valor explícito puede comportar una serie de estímulos – de coherencia, estéticos, lúdicos, prácticos o de otra índole- que, en determinados contextos, hagan más viable y clara la comprensión de la obra que a través del método convencional