Dynamic Vehicle Routing for Demand Responsive Transportation Systems
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DYNAMIC VEHICLE ROUTING FOR DEMAND RESPONSIVE TRANSPORTATION SYSTEMS by Rui Jorge Reis Gomes A thesis submitted to the Faculty of Engineering of the University of Porto in partial fulfillment of the requirements for the degree of Doctor in Transport Systems Under the supervision of: Professor Jorge Manuel Pinho de Sousa and Professor Maria Teresa Galvão Dias Porto, December 2012 This work was supported by the Portuguese National Science Foundation (FCT) under Grant SFRH/BD/42974/2008. Any opinions, findings and conclusions or recommendations expressed in this work are those of the authors and do not necessarily reflect the views of the National Science Foundation. “Pasmo sempre quando acabo qualquer coisa. Pasmo e desolo-me. O meu instinto de perfeição deveria inibir-me de acabar; deveria inibir-me até de dar começo. Mas distraio-me e faço. O que consigo é um produto, em mim, não de uma aplicação de vontade, mas de uma cedência dela. Começo porque não tenho força para pensar; acabo porque não tenho alma para suspender. Este livro é a minha cobardia.” Fernando Pessoa, O Livro do Desassossego ABSTRACT Buses circulating with very low occupancy rates mean high costs for the operators, often leading to low frequencies and, as a consequence, to social exclusion, low perceived quality and degradation of the image of public transportation. Demand Responsive Transportation (DRT) services try to address these issues with routes and frequencies that may vary according to the actual observed demand. The advantages of DRTs in terms of social cohesion, mobility, traffic, or environment, are fairly obvious. However, in terms of financial sustainability and quality level, the design of this type of services may be rather complicated. Moreover, in terms of operation, DRTs are very dynamic, requiring the adaptation of solutions in real-time, in a multiple criteria context. The problems of designing and operating DRT services are closely related to the Vehicle Routing Problem (VRP), and in particular to the Dial-A-Ride Problem (DARP). Service design has a fundamental role in the success of DRT services and, therefore, decision- makers need to understand well how different ways of operating the service affect its performance. In this work, a general modeling framework for planning and managing DRT services was developed, starting with a comprehensive analysis of European best practices. Based on this framework, a Decision Support System (DSS) was designed and implemented. This DSS integrates both a simulation model and a constructive multi-objective heuristic. Our approach aimed at finding a good overall design by running a simulation of several demand-offer scenarios. This simulation encompasses the multi-objective heuristic approach to deal with the combinatorial nature of the problem and with the multiple perspectives of the different stakeholders. To assess the approach, we have simulated the operation of a night time DRT service, in the city of Porto, in Portugal. Passengers specify origins and destinations from a set of pre-defined possible stops, a pickup time, and a desired arrival time. Experiments with simple cases, inspired in real problems, have shown the potential of the approach for designing and managing quite different DRT services. From the simulation, a set of i guidelines was obtained and planners can use the developed DSS to design DRT services, achieving adequate trade-offs between cost levels and quality of service. KEYWORDS: Combinatorial Optimization. Simulation. Multiple-Objectives. Heuristics. Logistics and Transportation. ii RESUMO Os sistemas de transportes são um fator chave para a sustentabilidade económica e bem- estar social das comunidades. A eficiência económica do transporte público rodoviário tradicional assenta em níveis significativos de procura e padrões de mobilidade bem estabelecidos, sendo, portanto, mais adequado para zonas de média/alta densidade populacional. Oferecer um serviço de transporte público de qualidade em cenários de baixa procura, tais como zonas rurais dispersas ou em determinados períodos do dia nas áreas urbanas, é extremamente caro, levando, muitas vezes, a frequências baixas e, consequentemente, à perceção de um serviço de baixa qualidade e à degradação da imagem do serviço de transporte público. Os sistemas de transportes flexíveis (do inglês Demand Responsive Transportation, ou DRT) procuram endereçar este problema através de rotas e horários que podem variar de acordo com a procura efetiva observada. Dada esta flexibilidade adicional, o serviço de transporte fornecido pelos operadores torna-se mais eficiente, com rotas planeadas pouco antes do início do serviço, com melhores taxas de ocupação e veículos com características mais adequadas às necessidades de mobilidade dos utilizadores. Apesar das vantagens, em termos de sustentabilidade financeira e nível de qualidade de serviço o desenho deste tipo de serviços pode ser bastante difícil. Os problemas de desenho e operação de sistemas de transportes flexíveis são bastante semelhantes ao problema clássico de roteamento de veículos (do inglês Vehicle Routing Problem ou VRP) e, especialmente, aos modelos de transporte-a-pedido (do inglês Dial-A- Ride Problem ou DARP). O desenho dos serviços DRT tem uma importância fulcral no sucesso dos mesmos e por isso é importante não só resolver o modelo inerente de forma eficiente, mas também que os agentes de decisão percebam perfeitamente como diferentes formas de operar um serviço afetam o seu desempenho. Neste trabalho foi desenvolvida uma framework genérica para o planeamento e gestão de serviços DRT, partindo de uma análise aprofundada das melhores práticas na Europa. Com base nesta framework foi desenvolvido um Sistema de Apoio à Decisão, que inclui modelos de simulação e uma heurística construtiva multiobjectivo paralelizada para obter um conjunto de soluções eficientes de acordo com as múltiplas perspetivas dos diferentes intervenientes. iii Para avaliar a abordagem proposta, simulamos 2 horas de operação de um serviço DRT noturno na cidade do Porto. Experiências com casos simples, inspirados em problemas reais, demonstraram o potencial da abordagem proposta no desenho e gestão de um conjunto bastante alargado e diferenciado de serviços DRT. Os agentes de decisão podem usar o Sistema de Apoio à Decisão para desenhar serviços DRT que atinjam os objetivos de custo e qualidade de serviço almejados. PALAVRAS-CHAVE: Otimização Combinatória. Simulação. Heurística. Objetivos múltiplos; Logística e Transportes. iv PUBLICATIONS AND COMMUNICATIONS During this doctoral project several communications and publications were done, reflecting the progress of the work and our main achievements and contributions: Book chapters - “Roteamento de veículos dinâmico”. In B. Prata (Ed.), “Logística Urbana: fundamentos e aplicações”. Curitiba - Brasil: Editora CRV, 2012 Journal articles - “A Decision Support System for the design and operation of Demand Responsive Transportation systems”, submitted for publication, IEEE – IET Intelligent Transport Systems, January, 2013; - “A new Heuristic Approach for Demand Responsive Transportation”, submitted for publication, International Journal of Transportation, January, 2013 - “An integrated approach for the design of Demand Responsive Transportation services”, submitted for publication, European Journal of Operational Research, November, 2012; Awards - Best Poster Award, 2nd Industrial Engineering and Management Symposium – IEMS 2011, Porto, January, 2011; - Best PhD Paper Award, 7th Annual Meeting of the Portuguese Working Group on Transport Studies (GET), Nazaré, January 2010; Invited talks - Gomes, R., “DRT scheduling platform”, E3 Forum – Education, Employment and Entrepreneurship, Lisbon, Portugal, June, 2012 Conferences - “An integrated approach for the design of Demand Responsive Transportation services”, EWGT 2013 - 16th Euro Working Group on Transportation, Porto, Portugal, September, 2013; - “An integrated approach for the design and operation of Demand Responsive Transportation services”, WCTR 2013 - World Conference on Transport Research, Rio de Janeiro, Brazil, July, 2013; v - “An integrated approach for the design of Demand Responsive Transportation services”, TRISTAN VIII, San Pedro de Atacama, Chile, June, 2013; - “Dynamic Vehicle Routing for Demand Responsive Transportation Services”, 10th Annual Meeting of the Portuguese Working Group on Transport Studies (GET), Alcobaça, January, 2013; - “Dynamic Vehicle Routing for Demand Responsive Transportation Services”, 4th Industrial Engineering and Management Symposium, Porto, January, 2013; - “Design and operation of Demand Responsive Transportation systems”, 15th Euro Working Group on Transportation Meeting, Paris, France, September 2012; - “An integrated approach for the design of Demand Responsive Transportation services”, VeRoLog 2012 – 1st Conference of the EURO Working Group on Vehicle Routing and Logistics Optimization, Bologna, Italy, June 2012; - “Dynamic Vehicle Routing for Demand Responsive Transportation Services”, 9th Annual Meeting of the Portuguese Working Group on Transport Studies (GET), Tomar, January, 2012; - “Dynamic Vehicle Routing for Demand Responsive Transportation Services”, 3rd Industrial Engineering and Management Symposium, Porto, January, 2012; - “Contributions for the design and operation of Demand Response Transport Systems”, 25º ANPET - Congresso de Pesquisa e Ensino em Transportes, Brazil, November, 2011; - “Dynamic Vehicle Routing for Demand Responsive Transportation