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Les relations entre les transformations des paysages du val de Blois et le développement de la ville de Blois ne sauraient être comprises sans être étudiées avec les regards croisés d’archéologues, géoarchéologues, géophysiciens et historiens. Une telle démarche interdisciplinaire a été entreprise depuis 2013 dans le cadre d’un Projet collectif de recherche, en examinant la vaste plaine alluviale blésoise et le lit mineur, la Loire. C’est donc à la connaissance du milieu, pleinement transformé par les sociétés et l’action de l’eau, que l’on accède sur une grande surface. Les travaux ont permis d’identifier plusieurs franchissements de la Loire. Or, franchir la Loire à Blois est un enjeu stratégique, économique et politique qui dépasse bien souvent les seuls intérêts locaux. L’archéologie préventive a montré que le val de Blois est un territoire occupé sans interruption depuis au moins le IIIe siècle avant notre ère. C’est un espace caractérisé par ses croisements d’axes de communication, voie fluviale et carrefour de voies terrestres. Ainsi, le franchissement, quelle que soit sa forme (gué ou pont), est un point de rencontre très important qui pourrait avoir été à l’origine de la fixation de l’habitat et avoir favorisé l’émergence du phénomène urbain dans ce lieu. Dès la création de l’agglomération vers la fin du Ier siècle avant notre ou au tout début du Ier siècle de notre ère, cette configuration lui confère une place spécifique, et par nature singulière, dans le réseau urbain local et régional. The relationship between the transformations of the Blois Valley landscape and the development of the town of Blois cannot be understood without being studied from the combined perspectives of archaeologists, geoarchaeologists, geophysicists and historians. Such an interdisciplinary approach has been undertaken since 2013 as part of a collective research project, examining Blois’ vast alluvial plain the Loire’s minor river bed. The combined knowledge of this environment, fully transformed by societies and the action of water, has provided access to a large surface area. This work has enabled us to identify several routes across the Loire; however, crossing the Loire at Blois is a strategic, economic and political issue that often goes beyond local interests. Preventive archaeology has shown that the Blois Valley has been occupied without interruption since at least the 3rd century BC. It is an area characterised by its crossroads of communication routes, both river and land. The crossing, either by ford or bridge, is therefore an important meeting point, which could have been at the origin of the settlement and may have favoured the emergence of an urban phenomenon here. From the creation of the settlement towards the end of the 1st century BC or at the very beginning of the 1st century AD, this configuration gives it a specific and singular place in the local and regional urban network. Sólo una perspectiva cruzada entre arqueólogos, geoarqueólogos, geofísicos e historiadores permite comprender el estudio de las relaciones entre las transformaciones de los paisajes del valle de Blois y el desarrollo de la ciudad de Blois. Un procedimiento interdisciplinario de este tipo se ha llevado a cabo desde 2013 en el marco de un proyecto colectivo de investigación, durante el cual se ha estudiado la amplia llanura aluvial de Blois y el lecho menor, el río Loira. Es por el conocimiento del medio, el cual ha sido completamente transformado por las sociedades y la acción del agua, que se accede a una gran superficie. Las obras han permitido identificar numerosos franqueos del Loira. Ahora bien, cruzar el Loira en Blois constituye un verdadero desafío estratégico, económico y político, que supera a menudo los simples intereses locales. La arqueología preventiva ha demostrado que el valle del Blois es un territorio que ha sido ocupado ininterrumpidamente desde, a lo menos, el siglo III antes de nuestra era. Se trata de un espacio caracterizado por sus cruces de ejes de comunicación, vía fluvial y encrucijada de vías terrestres. Así, cualquiera sea la forma del franqueo -un vado o un puente- constituye un punto de encuentro muy importante, que puede haber sido el origen de la sedentarización del hábitat y haber favorecido el surgimiento del fenómeno urbano en ese lugar. Desde la creación de la aglomeración, hacia fines del siglo I antes de nuestra era o a comienzos del siglo I de nuestra era, esta configuración le ha otorgado un lugar específico, e intrínsecamente particular, dentro de la red urbana local y regional.

Avalanches are one of the main hazards in mountain areas, frequently causing extensive damage and impacting the road network, resulting in road closures. The extent of damage and disturbance is directly determined by the avalanche deposit characteristics, and in particular its volume. Yet, avalanche deposits are still poorly studied objects, and the variables responsible for the deposit volumes spatio-temporal variations as well as their geometric and snow characteristics remain largely unknown so far. Therefore, this thesis aims to provide further knowledge about deposit characteristics as well as temporal variations and deposit volumes controlling factors. For this purpose, the study is based on field surveys and the analysis of an event database conducted on two massifs of the French Alps. Our results show the importance of the snowpack characteristics at initiation of the avalanche as a factor controlling the characteristics of the final deposit. Our results pointed out the importance of a seasonal approach to determine the controlling variables of avalanche deposit volumes. The relationships between deposition volumes and avalanche paths morphological variables and local weather conditions are higher for winter than for spring. Meanwhile, the influence of meteorological variables is more important. Finally, although the vulnerability of the road network is essentially controlled by the proximity of the road to avalanche paths, a few meteorological factors favoring road cuts have been identified., Les avalanches représentent l’un des principaux aléas dans les zones de montagne, entrainant régulièrement des dégâts de grandes ampleurs et affectent le réseau routier, entraînant des coupures de routes. L’ampleur de ces dommages et perturbations est directement conditionnée par les caractéristiques du dépôt d’avalanches, résultat final de l'écoulement, avec en premier lieu ses dimensions. Or, les dépôts d’avalanches sont restés des objets peu étudiés, les variables responsables des variations spatio-temporelles des volumes des dépôts ainsi que de leurs caractéristiques géométriques et nivologiques restent à ce jour mal connues. Cette thèse vise donc à améliorer la connaissance sur les caractéristiques des dépôts ainsi que les variations temporelles et les facteurs de contrôle des volumes des dépôts. Pour ce faire, le travail se focalise sur des relevés de terrains et l’étude d’une base de données événementielle opérés sur deux massifs des Alpes françaises. Nos résultats montrent l’importance des caractéristiques du manteau neigeux au moment du déclenchement de l’avalanche comme facteur de contrôles des caractéristiques du dépôt final. Nos résultats ont mis en avant l’importance d'une approche saisonnière pour déterminer les variables de contrôle des volumes des dépôts d’avalanches. Les liens entre les volumes des dépôts et les variables morphologiques des couloirs et les conditions météorologiques locales sont plus élevés pour l'hiver que pour le printemps. On note une influence plus importante des variables météorologiques. Enfin, si la vulnérabilité du réseau routier est essentiellement contrôlée par la proximité de la route aux couloirs d’avalanche, certains facteurs météorologiques favorisant des coupures de routes ont été identifiés.

Les services de livraison express font face au défi d’optimiser les routes de leurs véhicules alors que ceux-ci circulent dans un réseau routier où les temps de parcours varient en fonction du moment de la journée et où ils doivent répondre à l’arrivée dynamique de requêtes consistant à récupérer et livrer des colis. Notre but ici est de proposer une modélisation et une méthode de type heuristique pour résoudre ce problème. Nous commençons par explorer les travaux menés précédemment au sujet de l’arrivée dynamique des requêtes, des temps de parcours variables selon le moment de la journée et des collectes et livraisons dans les problèmes de tournées de véhicules. Ensuite, nous décrivons le problème de manière formelle sur le graphe du réseau routier avec des requêtes deux-points où l’objectif est de minimiser le temps total de parcours des véhicules et les temps de retard aux points de service et au dépôt. Par la suite, nous détaillons l’implémentation d’une méthode de résolution basée sur la recherche tabou utilisant une structure de voisinage basée sur la réinsertion d’une requête. Cette méthode utilise également la structure Dominant Shortest Path (DSP) qui considère plusieurs chemins alternatifs entre chaque paire de sommets, contrairement à l’approche traditionnelle où un chemin unique est fixé a priori. Finalement, nous testons notre méthode à l’aide de 390 instances générées de manière synthétique afin d’évaluer son efficacité ainsi que l’impact de certains aspects du problème et de la méthode de résolution. Les résultats démontrent une amélioration particulièrement importante due à l’utilisation de la structure DSP., Express delivery services face the challenge of optimizing the routes of their vehicles while they are moving in a road network where the travel times vary according to the time of day in order to serve dynamic requests which consist in collecting and delivering parcels. Our goal here is to propose a model and a heuristic method to solve this problem. We begin by exploring previous work on the topic of the dynamic arrival of requests, timedependent travel times and pickups and deliveries in vehicle routing problems. Afterwards, we describe the problem formally on the graph of the road network with the objective of minimizing the total travel time of the vehicles and lateness at the service points and at the depot. Then, we detail the implementation of a solving method based on tabu search using a neighbourhood structure based on the reinsertion of a request. This method also uses the Dominant Shortest Path (DSP) structure which considers multiple alternative paths between each pair of vertices, unlike the traditional approach where a single path is fixed a priori. Finally, we test our method using 390 instances generated synthetically in order to evaluate its efficiency as well as the impact of certain aspects of the problem and solution method. The results show a particularly significant improvement due to the use of the DSP structure.

Betweenness Centrality (BC) has proven to be a fundamental metric in many domains to identify the components (nodes) of a system modelled as a graph that are mostly traversed by information flows thus being critical to the proper functioning of the system itself. In the transportation domain, the metric has been mainly adopted to discover topological bottlenecks of the physical infrastructure composed of roads or railways. The adoption of this metric to study the evolution of transportation networks that take into account also the dynamic conditions of traffic is in its infancy mainly due to the high computation time needed to compute BC in large dynamic graphs. This paper explores the adoption of dynamic BC,i.e.,BC computed on dynamic large-scale graphs, modeling road networks and the related vehicular traffic, and proposes the adoption of a fast algorithm for ahead monitoring of transportation networks by computing approximated BC values under time constraints. The experimental analysis proves that, with a bounded and tolerable approximation, the algorithm computes BC on very large dynamically weighted graphs in a significantly shorter time if compared with exact computation. Moreover, since the proposed algorithm can be tuned for an ideal trade-off between performance and accuracy, our solution paves the way to quasi real-time monitoring of highly dynamic networks providing anticipated information about possible congested or vulnerable areas. Such knowledge can be exploited by travel assistance services or intelligent traffic control systems to perform informed re-routing and therefore enhance network resilience in smart cities.

TRB 2021, Transportation Research Board 100th Annual Meeting - A Virtual Event, Washington DC, ETATS-UNIS, 05-/01/2021 - 29/01/2021; The design of network-wide schemes requires computationally efficient traffic models. The Macroscopic Fundamental Diagram (MFD) is a promising tool for such an application. Unfortunately, current semi-analytical approaches require an inaccurate network reduction to a corridor. Our methodology allows us to estimate the MFD for general networks, without the information loss induced by the reduction of networks to corridors. The model is based on the method of cuts, but can account for different demand patterns, and determine the upper bound of network flow. Thereby, we consider flow conservation and the effects of spillbacks at the network level. Furthermore, we propose an overall framework which decomposes the network into a set of corridors, and then applies our model to each of them while taking into account the dependencies across corridors (e.g. due to turning flows and spillbacks). Aggregating the results leads then to a network MFD. The proposed framework applies to any general network, and we show a proof of concept using a simple but sufficient case study. We compare the results to the original method of cuts, and a ground truth derived from a microscopic simulation. Analysis reveals a strongly reduced error of the estimated MFD based on our method, compared to the currently applied approach. The potential of this methodology lies in its implementation simplicity and reduced computational cost.

TRB 2021, Transportation Research Board 100th Annual Meeting - A Virtual Event, Washington DC, ETATS-UNIS, 05-/01/2021 - 29/01/2021; Departure time choice models have a crucial role in transportation network planning in order to provide planners with predictions about the optimal traffic load. This paper introduces a new dynamic departure time choice framework based on the so-called Mean-field Games (MFGs) theory proposed by Lasry and Lions. MFGs models aim to analyze large population differential games. This feature gives us a unique opportunity to design a departure time choice equilibrium model in a scale-free transportation system. The proposed framework is the combination of two components: (i) the reaction of travelers to the traffic congestion by choosing their departure time to optimize the travel cost; (ii) the aggregation of the actions of the travelers, which determines the congestion level of the system. The first component corresponds to a classical game theory model, while the second one captures the interactions of the travelers at the macroscopic level. We use the generalized bathtub model recently proposed by Jin to represent the traffic dynamics at the network level. First, we provide a continuous model to investigate the equilibria and then give a discrete approximation of the system from deterministic differential games models. Finally, we show on a real test case that the model can represent the departure time choice equilibrium for multiple preferred travel time with heterogeneous trip lengths wile the framework is capable of considering a large number of players.

TRB 2021, Transportation Research Board 100th Annual Meeting - A Virtual Event, Washington DC, ETATS-UNIS, 05-/01/2021 - 29/01/2021; The work proposes a multi-modal regional mean speed regression analysis for the city network of Athens, Greece. The dataset from pNUEMA experiment is used in the present context. Accumulations and mean speeds of different modes are estimated and compared to each other. Besides, the mean running speeds of all modes are also computed and compared. The mean speed of each mode is assumed to be a linear combination of accumulations of all modes and regression analysis is performed. Ordinary Least Squares (OLS) and Partial Least Squares (PLS) methods are used in the current work. It is noticed that multicollinearity between different modes is weak in the current dataset. The quality of multi-modal regression fits is compared to the uni-modal ones, where the mean speed of a given mode is assumed to be a function of the accumulation of that mode only. It is concluded that multi-modal regression fits outperform their uni-modal counterparts in terms of R2 and Root Mean Squared Relative Error (RMSRE).

This study reviews existing computational methods to calculate simulation-based dynamic network equilibrium. We consider a trip-based multi-modal approach for the dynamic network loading. Mode and path choices are carried out at the same level; therefore, travel times depend on the travel path and the mode attributes of travelers. This study develops a multi-class model with several parameters per class. Two different categories of algorithms (heuristic and meta-heuristic) are considered in order to solve the discrete DTA problem. Finally, we analyze the equilibrium in a large-scale multi-modal DTA test case (Lyon 6th + Villeurbanne) in order to investigate the performance of different optimization approaches to solve trip-based DTA. The results show that, in a multimodal and heterogeneous setting, the meta-heuristic methods provide better solutions than the heuristic methods in terms of optimality and computation time. These improvements are even more significant than in a homogeneous setting.

Can dynamic ride-sharing reduce traffic congestion? In this paper we show that the answer is yes if the trip density is high, which is usually the case in large-scale networks but not in medium-scale networks where opportunities for sharing in time and space become rather limited. When the demand density is high, the dynamic ride-sharing system can significantly improve traffic conditions, especially during peak hours. Sharing can compensate extra travel distances related to operating a mobility service. The situation is entirely different in small and medium-scale cities when trip shareability is small, even if the ride-sharing system is fully optimized based on the perfect demand prediction in the near future. The reason is simple, mobility services significantly increase the total travel distance, and sharing is simply a means of combating this trend without eliminating it when the trip density is not high enough. This paper proposes a complete framework to represent the functioning of the ride-sharing system and multiple steps to tackle the curse of dimensionality when solving the problem. We address the problem for two city scales in order to compare different trip densities. A city scale of 25 km 2 with a total market of 11,235 shareable trips for the medium-scale network and a city scale of 80 km2 with 205,308 demand for service vehicles for the large-scale network over a 4-hour period with a rolling horizon of 20 minutes. The solutions are assessed using a dynamic trip-based macroscopic simulation to account for the congestion effect and dynamic travel times that may influence the optimal solution obtained with predicted travel times. This outperforms most previous studies on optimal fleet management that usually consider constant and fully deterministic travel time functions.

The main goal of this dissertation is to answer one of the critical questions about dynamic ride-sharing services: Can dynamic ride-sharing reduce congestion? In this thesis, we propose a simulation-based optimization framework for dynamic ride-sharing. Then using this framework, we assess the dynamic ride-sharing impact on two different network scales to find the answer to this question. When assessing the dynamic ride-sharing problem, two important points should be considered. First, how the ride-sharing system serves the network demand and second, how the ride-sharing system is impacted by the network and in particular by congestion. Then we can assess the impact of such a service on the network. Most of the existing approaches focus on the first point, i.e., designing the demand matching while using basic assumptions for the second point, mainly constant travel times. The proposed method in this thesis can outperform the existing methods in the literature. The optimization algorithm can provide high-quality solutions in a short time. Our solution approach is designed to be exact for small samples. Then, to be able to handle the large-scale problems, it is extended with several heuristics that keep the general design for the solution method but significantly reduce its computation time. In the simulation component, a "Plant Model" is applied based on the "Trip-based Macroscopic Fundamental Diagram (MFD)" to represent the traffic dynamics reality and a "Prediction Model" is applied based on the mean-speed to be used during the assignment process. We perform an extensive simulation study (based on real-world traffic patterns) to assess the influence of dynamic ride-sharing systems on traffic congestion. In the medium-scale (Lyon 6 + Villeurbanne), the results showed that ride-sharing could not significantly improve the traffic situation. High levels of market-share add additional travel distance and travel time to the trips and lead to more traffic in the network. In large cities, the results are entirely different from those in small and medium-sized cities. In large-scale (Lyon city in France) simulations, the proposed dynamic ride-sharing system can significantly improve traffic conditions, especially during peak hours. Increasing the market-share and the number of sharing can enhance this improvement. Therefore, the proposed dynamic ride-sharing system is a viable option, alleviating stress on existing public transport, to reduce the network traffic in populated and large-scale cities., L'objectif principal de cette thèse est de répondre à l'une des questions essentielles sur les services de covoiturage dynamique : le covoiturage dynamique peut-il réduire la congestion ? Dans cette thèse, nous proposons un framework d'optimisation basé sur la simulation pour le covoiturage dynamique. Ensuite, à l'aide de ce framework, nous évaluons l'impact du covoiturage dynamique sur deux échelles de réseau différentes pour trouver la réponse à cette question. Lors de l'évaluation du problème du covoiturage dynamique, deux points importants doivent être pris en compte. Premièrement, comment le système de covoiturage répond à la demande du réseau et deuxièmement, comment le système de covoiturage est influencé par le réseau et en particulier par la congestion. Ensuite, nous pouvons évaluer l'impact d'un tel service sur le réseau. La plupart des approches existantes se concentrent sur le premier point, c'est-à-dire sur la conception de la correspondance de la demande, tout en utilisant des hypothèses de base pour le second point, principalement des temps de trajet constants. La méthode proposée dans cette thèse peut être plus performante que les méthodes existantes dans la littérature. L'algorithme d'optimisation peut fournir des solutions de haute qualité en peu de temps. Notre approche de solution est conçue pour être exacte pour les petits échantillons. Ensuite, pour pouvoir traiter les problèmes à grande échelle, elle est complétée par plusieurs heuristiques qui conservent la conception générale de la méthode de solution mais réduisent considérablement son temps de calcul. Dans la composante de simulation, un "Modèle d'usine" est appliqué sur la base du "Diagramme macroscopique fondamental (MFD) basé sur les déplacements" pour représenter la réalité de la dynamique du trafic et un "Modèle de prédiction" est appliqué sur la base de la vitesse moyenne à utiliser pendant le processus d'affectation. Nous réalisons une étude de simulation approfondie (basée sur des modèles de trafic réels) pour évaluer l'influence des systèmes de covoiturage dynamiques sur la congestion du trafic. À l'échelle moyenne (Lyon 6 + Villeurbanne), les résultats ont montré que le covoiturage ne pouvait pas améliorer de manière significative la situation du trafic. Des parts de marché élevées augmentent la distance et la durée des trajets et entraînent une augmentation du trafic sur le réseau. Dans les grandes villes, les résultats sont totalement différents de ceux des villes petites et moyennes. Dans les simulations à grande échelle (ville de Lyon en France), le système de covoiturage dynamique proposé peut améliorer considérablement les conditions de circulation, en particulier aux heures de pointe. L'augmentation de la part de marché et du nombre de covoiturages peut renforcer cette amélioration. Par conséquent, le système de covoiturage dynamique proposé est une option viable pour réduire la pression sur les transports publics existants et diminuer le trafic du réseau dans les villes peuplées et de grande taille.

Contrary to the well-recognised relation between railroad infrastructure and emerging cities in the Belgian colony, the development of the Congolese road network was more closely connected to accessing the colonial hinterland and the expanding the rural economy. This latter link remains underresearched in both Congo’s and Africa’s transportation history, even if the colonial government equally considered road infrastructure a tool of empire. This article deconstructs this super-reducing concept of tools of empire in search of a better understanding of the complex reality of how centrally-defined road policies landed ‘on the ground’ in the vast Congolese hinterland. Studying the interwar development of the road network in the Cataractes-Nord region demonstrates how everyday colonial policymaking relied deeply on the aptitude and agency of private entrepreneurs and government officials alike, in a first step to truly understand the forces at play in the opening up of the Congolese countryside. Contrairement à la relation bien reconnue entre le développement de l’infrastructure ferroviaire et les villes émergentes de la colonie belge, le développement du réseau routier congolais était plus étroitement lié à l’accès à l’arrière-pays colonial et à l’expansion de l’économie rurale. Ce dernier lien reste trop peu investigué dans l’histoire des transports au Congo et en Afrique, même si le gouvernement colonial considérait également l’infrastructure routière comme un « tool of empire » (« outil d'Empire »). Cet article déconstruit ce concept réducteur de « tool of empire » en cherchant à mieux comprendre la réalité complexe de la façon dont les politiques routières du niveau central ont été transposées sur le terrain dans l’arrière-pays congolais. L’étude du développement du réseau routier pendant l’entre-deux-guerres dans la région des Cataractes-Nord montre comment l’élaboration quotidienne des politiques routières coloniales reposait considérablement sur l’aptitude et la capacité d’action des entrepreneurs privés et des fonctionnaires du gouvernement, dans un premier temps pour comprendre les forces en jeu dans l’ouverture de la campagne congolaise.

DSC 2020 Europe - Driving Simulation Conference Europe, Antibes, FRANCE, 09-/09/2020 - 11/09/2020; This paper presents a proof-of-concept work on using the procedural modeling approach to facilitate the creation of virtual environments defining the context of a simulated scenario. The work makes use of features of Esri CityEngine, a grammar-based modeling software, specialized for urban planning, in generating and controlling the distribution of the 3D assets in virtual environments. Two use cases where this approach was successfully applied will be also presented. The paper opens discussions on the advantages/limits and potential of this approach.

KES AMSTA 2020, 14th International Conference on Agents and Multi-Agent Systems: Technology and Applications - Virtual conference, Split, CROATIE, 17-/06/2020 - 19/06/2020; Today policy makers face an ever more complex traffic system. While they need to ensure smooth traffic flows in the cities, at the same time an acceptable level of service must be provided in remote areas. Autonomous taxis (AT) offer the opportunity to manage car traffic at low operational cost and they can be appropriate alternatives for the driven vehicles. In this paper, we propose a multi-agent system to find the best dispatching strategy for a fleet of AT. In the dispatching process, we aim to satisfy both passengers and providers objectives and priorities. To be able to apply the method on large-scale networks, we introduce a clustering method to cluster the requests every minute and then solve the assignment problem for the requests inside each cluster. As the network congestion can have significant impacts on the vehicles speed and travel time especially considering the private cars that are driving in the system besides the taxis, an agent-based simulation platform is used to simulate the function of the AT fleet. We use the trip-based Macroscopic Fundamental Diagram (MFD) to simulate the time evolution of traffic flows on the road network and update the traffic situation in the system every second to represent the real traffic dynamics. We address the problem for a large city scale of 80 km2 (Lyon city in France) with more than 480,000 trips over 4 hours period containing the morning peak. The experimental results with real data show that the proposed multi-agent system is efficient in terms of serving all the requests in a short time satisfying both passengers and providers objectives.

Landscape anthropization through habitat loss and fragmentation is one of the main threats to biodiversity. This PhD (CIFRE funding) was carried out in at INRAE Toulouse (Dynafor lab) in collaboration with the Conservatoire des Espaces Naturels de Midi-Pyrénées (CENMP). It aimed at a better understanding of the impacts of light pollution and road expansion on bats, two major and inevitable elements of anthropization, using a landscape ecology framework applied to bat conservation. This work is structured in 4 sections: (i) by means of an exhaustive review of bat telemetry studies in Europe and North America, I explored how landscape anthropization influenced bat mobility through mean home range sizes and commuting distances; (ii) using simultaneous acoustic sampling of bat communities at both edge and interior forest patches in 172 landscapes varying in terms of forest amount and road density, I analyzed how forest fragmentation and road network shaped the taxonomic, functional and phylogenetic diversity of bat communities at multiple spatial scales; (iii) by developing models of species distribution and connectivity (least-cost path) at the scale of a large urban area, I assessed the effect of different street lighting extinction scenarios on landscape connectivity for three bat species; and(iv) using a field experiment, I tested the influence of landscape context around road underpasses on their use by bats and the efficiency of these structures in maintaining landscape connectivity while reducing the risk of collision with vehicles. While the first two sections of the PhD seek to better understand the mechanisms underlying the effects of landscape anthropization on bats, the last two axes are applied to their direct conservation by demonstrating how landscape ecology can contribute to improve existing measures.

Ce rapport présente une première application à grande échelle de la méthode RoadIno d'estimation de la sensibilité des réseaux routiers aux inondations. Cette méthode a été développée en 2018 dans le cadre du stage de Jules Jacquemet (ESGT). Elle permet d'estimer la période de retour d'inondation du réseau routier au niveau de chaque franchissement d'un cours d'eau. Elle a été appliquée ici à l'échelle de l'ensemble du département du Gard, et confrontée aux résultats obtenus sur ce même territoire lors du projet de recherche PrediFlood (2009-2012) et de la thèse de J.P. Naulin (2012). Les performances obtenues avec RoadIno sont sensiblement supérieures, et l'approche sera par ailleurs beaucoup plus facilement transposable à d'autres territoires.

The aim of this study is to solve the large?scale dynamic traffic assignment (DTA) model using a simulation?based framework, which is computationally a challenging problem. Many studies have been performed on developing an efficient algorithm to solve DTA. Most of the existing algorithms are based on path?swapping descent direction methods. From the computational standpoint, the main drawback of these methods is that they cannot be parallelized. This is because the existing algorithms need to know the results of the last iteration to determine the next best path flow for the next iteration. Thus, their performance depends on the single initial or intermediate solution, which means they exploit a solution that satisfies the equilibrium conditions more than explore the solution space for the optimal solution. More specifically, the goal of this study is to overcome the drawbacks of serial algorithms by using meta?heuristic algorithms known to be parallelizable and that have never been applied to the simulation?based DTA problem. This study proposes two new solution methods: a new extension of the simulated annealing and an adapted genetic algorithm. With parallel simulation, the algorithm runs more simulations in comparison with existing methods, but the algorithm explores the solution space better and therefore obtains better solutions in terms of closeness to the optimal solution and computation time compared to classical methods.

The main goal of this dissertation is to answer one of the critical questions about dynamic ride-sharing services: Can dynamic ride-sharing reduce congestion? In this thesis, we propose a simulation-based optimization framework for dynamic ridesharing. Then using this framework, we assess the dynamic ride-sharing impact on two different network scales to find the answer to this question. When assessing the dynamic ride-sharing problem, two important points should be considered. First, how the ridesharing system serves the network demand and second, how the ride-sharing system is impacted by the network and in particular by congestion. Then we can assess the impact of such a service on the network. Most of the existing approaches focus on the first point, i.e., designing the demand matching while using basic assumptions for the second point, mainly constant travel times. The proposed method in this thesis can outperform the existing methods in the literature. The optimization algorithm can provide high-quality solutions in a short time. Our solution approach is designed to be exact for small samples. Then, to be able to handle the large-scale problems, it is extended with several heuristics that keep the general design for the solution method but significantly reduce its computation time. In the simulation component, a "Plant Model" is applied based on the "Trip-based Macroscopic Fundamental Diagram (MFD)" to represent the traffic dynamics reality and a "Prediction Model" is applied based on the mean-speed to be used during the assignment process. We perform an extensive simulation study (based on real-world traffic patterns) to assess the influence of dynamic ride-sharing systems on traffic congestion. In the medium-scale (Lyon 6 + Villeurbanne), the results showed that ride-sharing could not significantly improve the traffic situation. High levels of market-share add additional travel distance and travel time to the trips and lead to more traffic in the network. In large cities, the results are entirely different from those in small and medium-sized cities. In large-scale (Lyon city in France) simulations, the proposed dynamic ride-sharing system can significantly improve traffic conditions, especially during peak hours. Increasing the market-share and the number of sharing can enhance this improvement. Therefore, the proposed dynamic ride-sharing system is a viable option, alleviating stress on existing public transport, to reduce the network traffic in populated and large-scale cities. The main goal of this dissertation is to answer one of the critical questions about dynamic ride-sharing services: Can dynamic ride-sharing reduce congestion? In this thesis, we propose a simulation-based optimization framework for dynamic ridesharing. Then using this framework, we assess the dynamic ride-sharing impact on two different network scales to find the answer to this question. When assessing the dynamic ride-sharing problem, two important points should be considered. First, how the ridesharing system serves the network demand and second, how the ride-sharing system is impacted by the network and in particular by congestion. Then we can assess the impact of such a service on the network. Most of the existing approaches focus on the first point, i.e., designing the demand matching while using basic assumptions for the second point, mainly constant travel times. The proposed method in this thesis can outperform the existing methods in the literature. The optimization algorithm can provide high-quality solutions in a short time. Our solution approach is designed to be exact for small samples. Then, to be able to handle the large-scale problems, it is extended with several heuristics that keep the general design for the solution method but significantly reduce its computation time. In the simulation component, a "Plant Model" is applied based on the "Trip-based Macroscopic Fundamental Diagram (MFD)" to represent the traffic dynamics reality and a "Prediction Model" is applied based on the mean-speed to be used during the assignment process. We perform an extensive simulation study (based on real-world traffic patterns) to assess the influence of dynamic ride-sharing systems on traffic congestion. In the medium-scale (Lyon 6 + Villeurbanne), the results showed that ride-sharing could not significantly improve the traffic situation. High levels of market-share add additional travel distance and travel time to the trips and lead to more traffic in the network. In large cities, the results are entirely different from those in small and medium-sized cities. In large-scale (Lyon city in France) simulations, the proposed dynamic ride-sharing system can significantly improve traffic conditions, especially during peak hours. Increasing the market-share and the number of sharing can enhance this improvement. Therefore, the proposed dynamic ride-sharing system is a viable option, alleviating stress on existing public transport, to reduce the network traffic in populated and large-scale cities.

In this paper, we propose a control and optimization framework to reduce network-wide emissions in an urban traffic network. The framework is comprised of two layers. The first layer (optimal green routing) predicts the optimal splitting coefficients for all Origin-Destination (OD) pairs crossing the city center or bypassing. As implementing optimal routing strategies on the field is almost impossible as we do not have direct ontrol over the user's decisions, we choose to balance travel time through gating at the city perimeter so that the usual Dynamic User Equilibrium (DUE) discipline matches the optimal splitting coefficients. The second layer then adjusts inflows at the city gates to the DUE solution based on the instantaneous travel times corresponding to the optimal routing strategy for each OD pair. The accumulation-based Macroscopic Fundamental Diagram (MFD) model of a single reservoir city with seven arterial routes and six bypass alternatives is developed. A Linear programming problem is formulated to determine the optimal splitting coefficients and a Nonlinear Model Predictive Control (NMPC)-based gating control strategy is designed to track the optimal splitting coefficients. The network-wide emission control framework is compared to three other gating strategies aiming to (i) optimize traffic conditions or (ii) minimize emissions, in the inner-city only, and (iii) optimize traffic conditions in the whole network. A comprehensive analysis conducted on all four approaches is presented. We compare the results of the controlled case with respect to the uncontrolled case and with respect to each other. The comparison results show that: (i) the proposed network-wide emission control strategy significantly outperforms the other two simpler control strategies focusing on inner-city only in reducing the total emission, (ii) but also improves the in total time spent and mean speed at the network-level.

Flow limitation due to spillbacks between reservoirs in Macroscopic Fundamental Diagram (MFD) based approaches is still not fully understood. In a previous paper, we analyzed flow exchange properties and formulated new merging and diverging models, different from those previously proposed in the literature. However, both the latter and our approach received very little support from aggregated link-scale data (real or simulated). The contribution of this study is to validate different MFD-based modeling approaches vs. microscopic simulation using an artificial Manhattan network and then compare the microsimulation results with the MFD-based ones. These comparisons first allow us to investigate and calibrate the network entry capacity, known as the entry supply function. Besides demand pro-rata and endogenous merging scheme, entry flow based on First-In-First-Out rule is also analyzed. Finally, we also show that the outflow diverging scheme is critical to reproduce microsimulation results well regarding the network exit and demonstrate the1 limitations of widely used approach of a decreasing outflow demand with independent partial outflow treatment.

Ce rapport présente une synthèse des résultats de l'action 8 : appui au SCHAPI conduite dans le cadre de la convention Ifsttar-DGPR 2019 n°2201189104 du 4 Juin 2019. Le programme de cette action regroupait les contributions listées ci-dessous: - Première application à grande échelle de la méthode RoadIno permettant l'évaluation de la sensibilité des réseaux routiers à l'inondation, dans le département du Gard. - Application et évaluation de méthodes de cartographie automatisée des inondations dans un contexte de crues éclair, et illustration de la sensibilité des résultats à l'information MNT utilisée en entrée. - En cas d'occurrence d'un événement de crue remarquable, réalisation d'une enquête de terrain post-crue pour la reconstitution des débits de pointe sur les cours d'eau non jaugés. Une enquête de ce type a été conduite suite aux crues ayant touché les départements des Alpes Maritimes et du Var les 23-24 novembre et le 1er décembre 2019.

Solving a dynamic traffic assignment problem in a transportation network is a computational challenge. This study first reviews the different algorithms in the literature used to numerically calculate the User Equilibrium (UE) related to dynamic network loading. Most of them are based on iterative methods to solve a fixed-point problem. Two elements must be computed: the path set and the optimal path flow distribution between all origin-destination pairs. In a generic framework these two steps are referred to as the outer and the inner loops, respectively. The goal of this study is to assess the computational performance of the inner loop methods that calculate the path flow distribution for different network settings (mainly network size and demand levels). Several improvements are also proposed to speed up convergence: four new swapping algorithms and two new methods for the step size initialization used in each descent iteration. All these extensions significantly reduce the number of iterations to obtain a good convergence rate and drastically speed up the overall simulations. The results show that the performance of different components of the solution algorithm is sensitive to the network size and saturation. Finally, the best algorithms and settings are identified for all network sizes with particular attention being given to the largest scale.

In the context of Smart Cities, there is a growing need to inform drivers, anticipate congestion and take action to manage the state of the traffic flow on the road network. This need has driven the development of a large number of traffic forecasting methods. The last decades have seen the rise in computing power, in storage capacity and in our ability to process information in real-time. More and more road segments are equipped with traffic sensors. These evolutions are new elements to take into consideration in order to design accurate traffic forecasting algorithms. Despite the large amount of research efforts on this topic, there is still no clear understanding of which criteria are required in order to achieve a high forecasting performance at the network scale. In this thesis, we study two real datasets collected in two main French cities: Lyon and Marseille. The Lyon dataset describes the traffic flow on an urban network. The Marseille dataset descrobes the traffic flow on urban freeways. We evaluate the performance of methods from different fields: time series analysis (autoregressive models), and different subfields of machine learning (support vector machines, neural networks, nearest-neighbors regression). We also study different neighborhood selection strategies in order to improve the forecasting accuracy, while decreasing the complexity of the models. We evaluate a well-known approach (Lasso) and apply for the first time on traffic data a method based on information theory and graphical models (TiGraMITe), which has shown very effective on similar physics applications. Our experimental results confirm the usefulness of neighborhood selection mechanisms in some contexts and illustrate the complementarity of forecasting methods with respect to the type of network (urban, freeway) and the forecasting horizon (from 6 to 30 minutes).; Dans le contexte de la ville intelligente, le besoin d’informer, d’anticiper, et d’agir sur l’état du réseau routier est à l'origine du développement de nombreuses méthodes de prévision de trafic. L’augmentation de nos capacités à stocker et à traiter des données, notamment en temps réel, ainsi que le nombre croissant de segments de routes équipés de capteurs sont de nouveaux éléments à considérer lors du choix d’une méthode de prévision. Malgré de nombreux travaux de recherche, nous ne disposons toujours pas d’une compréhension claire des critères permettant de prédire efficacement à l’échelle d’un réseau routier. Dans cette thèse, nous nous appuyons sur deux jeux de données réelles, collectés respectivement sur le réseau urbain de la Métropole de Lyon, et sur les autoroutes urbaines de Marseille. Nous étudions la performance de différentes méthodes issues de la littérature statistiques des séries temporelles (méthodes autorégressives) et de la littérature de l’apprentissage artificiel (machine à vecteurs de support, réseaux de neurones). Nous étudions également l’apport de différentes stratégies de sélection de voisinage (sélection d’un sous-ensemble de capteurs utiles pour la prévision d’un capteur en particulier) pour améliorer la qualité de la prévision, tout en diminuant la complexité des modèles appris. Nous comparons ainsi une approche classique (la sélection Lasso) et testons pour la première fois sur des données de trafic une méthode issue de la théorie de l’information, ayant de très bons résultats sur des problèmes similaires de physique (tigramite). Nos résultats expérimentaux confirment l’utilité de méchanismes de sélection de voisinage et illustrent la complémentarité des approches de prévisions, selon le type de réseau (urbain, autoroute) et l’horizon de prévision (de 6 à 30 minutes)

International audience; Le nouvel horizon sénégalais. Peuplement et urbanisation des campagnes occidentales aux périphéries orientales Résumé Alors que le peuplement du territoire sénégalais se concentrait dans quelques parties du pays, plusieurs processus contemporains remettent en question la répartition spatiale de la population : la densification de zones auparavant peu habitées ; l'urbanisation qui s'étend à l'ensemble du pays et qui se double de la transformation de bourgades rurales en communes de plein exercice ; la croissance du réseau routier jusque dans les parties du territoire auparavant isolées des centres urbains. Tandis que l'est du pays s'est longtemps considéré comme oublié et que la basse-Casamance demeure traversée de courants irrédentistes en partie dus à son éloignement du centre, le territoire national dans son ensemble semble rattrapé par des dynamiques spatiales qui ne concernaient que l'ouest du pays.

hEART 2019, 8th Symposium of the European Association for Research in Transportation, Budapest, HONGRIE, 04-/09/2019 - 06/09/2019; This work investigates network-related trajectory features to unravel trips that the most contribute to the system under-performance. When such trips are identified, features analysis also permits to identify the best alternatives in terms of routes to make the system to its optimum. First, data mining is carried out on trajectories obtained from reference dynamic traffic assignment (DTA) simulations in a real-world network, based on User-Equilibrium (UE) and System-Optimum (SO). This helps us (i) to target the trajectories to be changed, and (ii) to identify their main features (trip lengths, experienced travel time, path marginal costs, and network-related features such as betweenness centrality and traffic light parameters, etc.). Similarity analysis based on Longest Common Subsequence, Principle Component Analysis are the main methods that are performed to carry out descriptive analysis of trajectories. Supported Vector Machine is then used to determinate the features with regards to their contribution to better network performance.

Aujourd’hui, les villes connaissent une croissance exponentielle de leur population. Le suivi de cette croissance est essentiel pour garantir le bien-être des citadins. Cependant, ce suivi nécessite des bases de données cartographiques sur les différents aspects de la morphologie urbaine. Bien que l’interférométrie satellite radar à synthèse d’ouverture (RSO) soit largement exploitée pour la création de modèles numériques de terrain (MNT) et le calcul de la déformation du terrain, son usage en milieu urbain est bien plus complexe, notamment en raison des multiples zones d’inversion, d’occlusion et d’ombre présentes dans ces milieux. Tout d’abord, des algorithmes d’extraction de l’information 2D sur la morphologie urbaine (emprise au sol des bâtiments, occupation du sol et réseau routier), s’appuyant uniquement sur des données satellites RSO mono-polarisées, ont été implémentés. L’accent a été mis sur le caractère robuste, automatique et rapide de ces algorithmes. Les résultats obtenus sont comparables à ceux présentés à partir d’images aéroportées. Après avoir testé les algorithmes à partir des images satellites en amplitude, l’apport des produits interférométriques (interférogramme et cohérence) a été évalué. Il résulte de cette approche en deux étapes que les produits interférométriques, en raison de leur faible résolution, ont un réel impact uniquement sur la segmentation des éléments de tailles importantes. En ce qui concerne l’extraction de l’information 3D sur la hauteur des bâtiments, une procédure s’appuyant sur deux interférogrammes, l’un possédant une petite ligne de base, et l’autre une grande ligne de base, a été développée. L’utilisation de ces deux interférogrammes permet de détecter la majorité des sauts de phase, tout en conservant une précision convenable. Toutefois, cette procédure n’aurait pas été optimale sans l’apport des informations 2D extraites ci-dessus, tant pour le calcul de la hauteur des bâtiments que pour la génération du MNT. L’apport de ces informations a, notamment, permis d’exclure les zones d’inversion, d’occlusion et d’ombre, qui génèrent une valeur aléatoire pour la phase., Nowadays, towns are undergoing exponential growth. The monitoring of their expansion is essential to guarantee the welfare of citizens. To do that, cartographic databases of multiple aspects of urban morphology are required. Satellite imaging using interferometric synthetic aperture radar (SAR) is widely applied to generate digital terrain models (DTM) and calculate ground deformations. However, satellite interferometric SAR in urban zones is much more complex, due in part to numerous reversal, occlusion and shaded areas. First of all, algorithms to extract the 2D information on urban morphology (building footprints, land cover and road network) have been implemented. These algorithms are based only on single-polarized satellite SAR data. The decision on the type of approach was driven by robustness, automatic and speed criteria. Achieved results are comparable to results presented with aircraft images. Once algorithms have been tested on satellite intensity images, the contribution of interferometric products (interferogram and coherence) have been evaluated. Thanks to this two-step approach, we found that interferometric products have a significant contribution to segment big size objects only. Concerning the extraction of the 3D information on building heights, a method based on two interferograms, with a short and a long baseline respectively, has been developed. This approach allows to detect a large number of phase jumps while preserving a reasonable accuracy. However, this method would not have been possible without the contribution of the 2D information extracted earlier, whether for the calculation building height or for the generation of DTM. Among other things, this additional information allows to resolve the phase disturbance generated by reversal, occlusion and shaded areas.

International audience; Les villes organiques (en opposition aux villes planifiées) se construisent sur le temps long, par ajouts successifs, s'organisant depuis des traces anciennes pour créer la trame actuelle. Des trois éléments morphologiques qui les composent (bâtis, parcelles, voierie), le réseau viaire est celui le moins susceptible de subir des modifications brusques au cours du temps. Il est ajusté par touches ponctuelles, ou bien s'étend sur le paysage environnant. Lorsque sa modification se produit à l'échelle globale, dans une ville, l'événement est suffisamment rare pour acquérir une renommée mondiale, comme celle d'Haussmann à Paris ou de Cerdà à Barcelone au XIXe siècle. Cette croissance structurelle progressive le rend porteur d'information. Les réseaux viaires s'organisent selon une topologie et une topographie qui n'est pas étrangère à la culture et au lieu dans lesquels ils s'incluent. Ils sont issus des choix faits pour prioriser l'accès à certaines parties du territoire. L'objet de ce travail est de présenter comment l'analyse de la trame viaire nous permet de comprendre les structures, à différentes échelles, de nos villes ; les mobilités qu'elles abritent ; les effets de cette infrastructure, socle de nos mobilités, sur leur territoire ; et d'aider ainsi les aménagements urbains futurs. Nous proposons d'explorer comment la structure viaire peut être révélatrice de l'Histoire de la ville dans laquelle elle se situe, et comment au cours du temps, sa forme influe sur l'organisation du territoire. La méthode construite pour cela est générique : elle peut s'appliquer à n'importe quelle ville dont on dispose du réseau viaire (donnée largement disponible à l'échelle mondiale sur OpenStreetMap). Elle utilise les outils de la théorie des graphes, appliqués au squelette de nos rues : la géométrie brute du réseau. Celle-ci s'émancipe des largeurs de rues, sens de circulation, limite de vitesse imposée, qui sont des attributs qui peuvent changer au cours du temps.

MT-ITS 2019, 6th International Conference on Models and Technologies for Intelligent Transportation Systems, Cracovie, POLOGNE, 05-/06/2019 - 07/06/2019; Graph-based analysis has proven to be a good approach to study topological vulnerabilities of road networks through specific metrics, such as betweenness centrality (BC). Even though BC of unweighted, undirected graphs has been widely adopted to identify critical road segments and intersections, given the very high number of potentially highly-traversed paths flowing through them, congestion and vulnerability are strongly influenced also by static and dynamic context factors, such as road capacity, speed limits, travellers' behaviors, accidents, social gatherings and maintenance operations. In this paper, we focus on the analysis of BC on dynamically weighted graphs, used as a model of a road network and associated dynamic information (e.g. travel time). The aim is to discover correlations between the centrality metric and vehicle flows, both in space and in time. The analysis proves the existence of relevant spatio-temporal correlations that provide useful information about the characteristics of road networks and the behavior of drivers. In particular, we identify the existence of anti-correlations that point out forecasting properties of BC when computed on dynamic graphs.These properties justify the usage of the metric for the implementation of next-generation proactive, data-driven urban monitoring systems. These systems are expected to empower urban planners and traffic operators with novel intelligent solutions to reduce traffic congestion and vulnerability risks, therefore contributing to implement the vision of a more resilient and sustainable city.

TRB 2019, Transportation Research Board 98th Annual Meeting, Washington, ETATS-UNIS, 13-/01/2019 - 17/01/2019; Calculating dynamic network equilibrium is a challenging problem. This study first analyzes the different frameworks for the simulation-based User Equilibrium (UE) in the literature. Most of them are based on solving a fixed-point problem by iterative methods. Two elements have to be determined: the path set between all origin-destination pairs and the optimal path flow distribution. The most advanced solution methods expressed the problem with two-layers, the outer and the inner loop, that tackle each element respectively. The goal of this study is to improve the inner loop, i.e. the path flow calculation. The first improvement is keeping the best assignment pattern during the inner loop iterations and send it to the outer loop. It improves the solution quality in trip-based traffic assignment because flows are then discretized into units of user, which makes the point-fix calculation much harder. This study proposes three new swapping methods and two new methods for the step size initialization that is used in each descent iteration. Moreover, this study proposes two alternative methods to initialize the path flow distribution at the beginning of the outer loop. Two quality indicators are considered to examine the quality of UE solution and then the methods are applied to three networks with different sizes (small, medium and large). The results show that the performance of different components of the solution algorithm is sensitive to the network size. Finally, the best configurations of the solution algorithms are recommended for all network sizes with a particular focus on the large-scale.

TRB 2019, Transportation Research Board 98th Annual Meeting, Washington, ETATS-UNIS, 13-/01/2019 - 17/01/2019; Multi-reservoir systems based on theMacroscopic Fundamental Diagram (MFD) look appealing to simulate traffic states at large urban scales. Nevertheless, flow limitation due to spillbacks between reservoirs is still not fully understood yet. Recently, we analyzed flow exchange properties and formulated new merging and diverging models, different from the ones previously proposed in the literature. However, both the latter and our approach received very little support from aggregated link-scale data (real or simulated one). The contribution of this study is to validate different MFD-based modeling approaches by using microscopic simulation. To this end, we focus on an artificial Manhattan network crossed by two regional paths (West-East and North-South). We then analyze the aggregated accumulation, inflow and outflow of these paths for different congestion scenarios, and compare the results with the outputs predicted by the MFD-based models. It is notably found that the outflow diverging scheme is critical to fairly reproduce microsimulation results. During congestion on-set, the widely used approach of a decreasing outflow demand with independent partial outflow treatment provides good estimation of transient states, but fails to predict reliable network unloading during congestion off-set. The modified approach we developed in our previous study takes advantage of setting the reservoir outflow demand to maximum and applying inter-dependency relationships between outflows to overcome this issue. To a lesser extend, using a demand pro-rata merging scheme, as it is usually done in the literature, would be the best option to determine partial inflows properly.

TRB 2019, Transportation Research Board 98th Annual Meeting, Washington, ETATS-UNIS, 13-/01/2019 - 17/01/2019; Generally, in perimeter control, congestion from inside the reservoir ismoved to the outside by manipulating the inflows which create queue. As in our settings, one of the routes have an alternative route (freeway), the total input demand of the network is distributed along the transfer route and a freeway. To solve the problem of demand flow distribution, in this work we applied a routing discipline corresponding to user equilibrium (UE). Therefore, drivers can choose a route with lower travel time that is no longer crossing the reservoir. Doing so, we are not only considering the side-effects of perimeter gating control in terms of congestion but we are also taking into account the external user adaptation to it. The main contribution of this paper compared to previous works is that the external UE discipline makes the input demand elastic from the reservoir point of view. The evaluation of the global system performance is then much more realistic. Note that the way we implement that external UE discipline with the MFD framework is also a contribution by itself. Further, we analyze the impact of routing on perimeter gating control and sheds some light on the side-effects (in terms of the queue, emissions, and total time spent) of perimeter gating control.

Network-level pavement maintenance programming is characterised by its high computational complexity. In this article, a novel modelling to solve this problem efficiently is proposed. In this modelling, careful care has been taken to reduce the search space and formulate the original problem as one of the well-known problems of the literature on mathematical optimisation. Efficient algorithms can therefore be used to find a solution. According to this approach, the maintenance programming problem is divided into two sub-problems: (i) the first performs a reduction of the search space by filtering road section maintenance alternatives based on technical criteria; (ii) the second computes a road network-level maintenance program by optimising efficiency subject to budget constraints. The section-level filtering of alternatives is modelled as a constraint satisfaction problem and solved using appropriate constraint satisfaction algorithms. The network-level maintenance programming is modelled as a generalised assignment problem, whose resolution is well documented in the literature on optimisation. This approach has shown to be very effective, with strong computational performances for different road network sizes.

hEART 2019, 8th Symposium of the European Association for Research in Transportation, Budapest, HONGRIE, 04-/09/2019 - 06/09/2019; In this paper, we propose optimal route guidance and Nonlinear Model Predictive Control (NMPC)-based gating control approach to reduce network-wide emission in an urban traffic network. An accumulation-based Macroscopic Fundamental Diagram (MFD) model of a single region city is developed to describe the evaluation of the traffic flows in a network. Moreover, a path flow distribution scheme using Dynamic User Equilibrium (DUE) discipline is designed to reproduce the driver's adaptation to controlled flow. The NMPC is developed to track the optimal green routing coefficients which will indirectly track the network-wide emission levels by manipulating the traffic flows into a region. Simulation results show the effectiveness of the proposed scheme in improving the traffic emissions inside and outside the perimeter. Comparative analysis of no control and NMPC shows that the proposed approach reduces emission by up to 13% as compared to the no control case.