Locating key stations of a metro network using bi-objective programming: discrete and continuous demand mode

This study proposes two bi-objective optimization problems for locating key stations of a metro network in both discrete and continuous demand modes. Traditionally, designing a metro network based on optimization techniques consists of two approaches. The first approach locates a number of alignments and their stations simultaneously, while the second approach involves locating key stations, designing a core network, and locating secondary stations. In locating key stations processed by a single objective model, the number of produced and attracted trips to the key stations is maximized. This paper considers a second objective for this stage to maximize the coverage of key stations on origin/destination (OD) trips. A fuzzy goal programming model is established to solve the bi-objective model and provide some Pareto-optimal solutions. The previous single objective model and the proposed model with continuous demand mode are applied to a real network. Results show that the proposed model significantly increases the coverage of key stations on OD trips with only a slight reduction in the number of produced and attracted trips

A clustering method for measuring accessibility and equity in public transportation service: Case study of Melbourne

This paper proposes a Modified Cumulative Accessibility (MCA) measure incorporating actual travel demand information (Origin-Destination trip patterns) to improve the accuracy of the measure as a reliable proxy for equity evaluation and amelioration in accessing Public Transportation (PT) services. The travel demand information is reflected into the MCA measure by evaluating and clustering PT and Private Vehicle Transportation (PVT) trip diaries. Both vertical and horizontal equities are measured for the network\u27s Transportation Analysis Zones (TAZs). To redress the inequities, a priority list of operational recommendations for each TAZ is identified. The proposed method is tested with the Greater Melbourne area datasets and the TAZs with the highest inequity along with prescribed operational recommendations are identified. In terms of equitable distribution of public transportation service, a major observation from the case study model was that the outer suburban areas located in the eastern side of the the Melbourne metropolitan area are relatively underserved as compared to the inner and western suburbs

An integrated global airline hub network design with fleet planning

International audienceThis study aims to locate optimal global hubs for an airline or a group of airlines to cover international flights between countries. Despite designing a hub network for regional flights, designing a hub network for international flights is considerably different because of the high frequency of medium-, or long-haul flights. Accordingly, designing a hub network without considering the fleet size and diversity is impossible. This study proposes three airline Hub Location Problems (HLPs) in a global scale with the following considerations: Ι) an HLP providing the possibility of operating the multi-leg flights by a limited fleet size, ΙΙ) an HLP respecting consideration (Ι) with the possibility to increase the efficiency of the fleet by taking the aircraft characteristics into account in the design of the hub network, and ΙΙΙ) an HLP respecting considerations (Ι) and (ΙΙ) with the possibility of fleet planning. These models are solved for several instance networks, being up to 300 networks, and compared with an HLP without these considerations. The results mainly demonstrated that ignoring the aircraft characteristics in an HLP can generate an inefficient or infeasible hub network configuration. In addition, the problem of a real international flight network was solved and the insights regarding designing an optimal hub network and fleet configuration were presented

Hazardous material transportation problems: A comprehensive overview of models and solution approaches

International audienceThis paper provides a comprehensive review in the domain of hazardous material transportation from an Operational Research point of view. The paper's focus lies on hazmat routing, routing-scheduling, and network design problems. The objective of this review paper is twofold: (1) reviewing the models’ assumptions, objectives and constraints, decisions, input parameters, basic modeling/solution techniques, and case studies, and (2) highlighting the underlying features and challenges in designing the models with different transportation modes. Besides, the most significant research gaps in the literature are identified through a systematic in-depth review at a micro-level. Finally, a set of promising future research directions is proposed upon from the authorities could draw better decisions. As a key finding after performing this review, we believe that a considerable number of promising future research directions consist in hybridizing different problems, i.e., amount to borrowing some key properties from a problem and integrating them into another problem. This has led to valuable research studies in the literature of hazmat transportation problems