Abstract

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.

Abstract

Introduction The importance of the transport infrastructure role is often described in the attempt to describe the characteristics of a “smart city”. Good planning and organization of communication networks contributes to the development of cities that are more fluid and user-friendly and sustainable, concepts underlying “smart cities”. The paper focuses on the impact on social organisation and on conception of transport intermodal infrastructures such as city-hubs inducing new and smarter practices of transport infrastructure, but also the urban dimension and their insertion through the actual city and, even more, by the creation of an entirely new neighbourhood and the preoccupation of a better quality of life. As part of the European research project FP7 “City-HUB”, 27 interchanges have been studied in nine European countries. The paper emphases on the implementation of the City-HUB interchange typology to the case study of Lille European Metropolis (MEL) where two contingent railway stations, Lille Flandres and Lille Europe, were analysed as a potential unique interchange named “Euraflandres”with socio-economic impacts and the possibility that it may become a “place” of life in the smart city. Methods Within the FP7 project City-HUB a literature review was conducted on the role and characteristics of interchanges in the cities and their contribution to smart cities [29]. For 27 interchanges in nine European countries, we have determined a number of relationships between these transport multimodal interchanges and their environment, and established a typology capturing different interchanges and a scheme for scoring their characteristics in terms of function and logistic dimensions (demand, number of transport modes, services and facilities, location in the city) and their local constraints. The governance framework was specified through carrying out semi-structured interviews with key interchange actors for each City-HUB case study that also questioned about the role of interchanges in local economies and their potential impact on that. The Lille Flandres and Lille Europe as a unique landmark “Euraflandres” were particularly studied to understand their characteristics and role to contribute to a smarter city. Results Based on the City-HUB typology, the “Euraflandres” gets a score of 9 because its demand is higher than 120,000 in daily passengers, includes 13 public and private transport modes (several PT, long distance coaches, car and bike), is located in the city centre and is included into a local plan of urban development and TOD definition. “Euraflandres” has all the characteristics for becoming an urban Landmark for the city of Lille. We show how this interchange gets a higher role for being a node on the international railway network, and how their inside and outside spatial and functioning reorganisation contribute to ease the use of public transport for travellers by introducing ITS, innovations in ticketing and providing new urban characteristics transforming transport infrastructures into new places to live. Conclusions Linking the smart city and the development made with “Euraflandres”, we have seen that an opportunity exists to join together the two Lille railway stations and urban Public Transport interchanges in order to combine a great urban interchange. It will procure advantages for increasing the accessibility for all destinations at urban Lille metropolis and regional level, but also at the national and international levels by the possibility offered by the French TGVs running on national network and the Railteam high speed trains such as Eurostar and Thalys. Each type of interchange, according to the identified functions and local constraints, should require the involvement of different stakeholders interchanges and the Lille City-HUB management with its stakeholders’ committees seems to be oriented to make effort for finding an agreed way for reducing conflicts, in order to better plan outcomes and to allow communities to have an influence over the future shape of the places where they live. The community-led participation is the first step to identify requirements and needs of operators (i.e. transport activities including services and facilities) and of users who will perceive the City-HUB as a transport node and a place where to have access to their mobility mode and where to carry out some other activities during their waiting time. Despite existing barriers (complex governance framework, physical barriers, functions and logistics to revise, local constraints), all the stakeholders are willing to improve the visibility and the functionality of these interchanges. “Euraflandres” has the role of developing activities and regenerating the urban environment, by transforming the surrounding area features. All this will make cities more convivial and fluid, answering to two key aspects of the Smart City, when we follow the definition of the smart city as a “fluid”, “intelligent” and “convivial” city by [4]. The extension of the Euralille neighbourhood where is located “Euraflandres”, is part of the Lille urban regeneration, still under construction, will provide new housing and also social housing for low income people and new city amenities transforming it in a new place to live transforming the current two separated interchange towards the future one landmark interchange with a higher share of sustainable and affordable public transport modes share. Document type: Article

Abstract

We conduct a Global Sensitivity Analysis (GSA) of urban-scale network performances to parameters representing a wide range of realistic dynamic loadings, decomposed in a choice of OD matrix, routing alternatives, and paths flow distribution. A special attention is given to the route alternatives generation, where overlapping metrics and selection methods are introduced to reproduce a wide variety of paths sets configuration. Paths flow distributions are calculated based on different equilibrium criteria. Several sets of simulations are conducted and analyzed graphically and then with a variance-based GSA method so as to get insights on how much and in which conditions each network loading parameter influences network performances by itself or by interaction. Results notably reveal that the demand level is the most decisive parameter since low values simply lead to free-flow conditions with no influence of the other parameters, whereas higher values lead to a wide diversity of network states going from close to capacity but stable to gridlocked. While a nonnegligible amount of this disparity is explained by the demand pattern parameter, the number of paths per OD, their overlapping, and the equilibrium criterion of the paths flow distribution are still influential enough to maintain the network close to its optimal capacity or to prevent the network from fast collapse (gridlock). The highlighted connection between spatial and temporal heterogeneities of the network states explains the gridlocking phenomena. These extracted insights are very encouraging for operational implementations. Document type: Article