Analysis and operational challenges of dynamic ride sharing demand responsive transportation models

There is a wide body of evidence that suggests sustainable mobility is not only a technological question, but that automotive technology will be a part of the solution in becoming a necessary albeit insufficient condition. Sufficiency is emerging as a paradigm shift from car ownership to vehicle usage, which is a consequence of socio-economic changes. Information and Communication Technologies (ICT) now make it possible for a user to access a mobility service to go anywhere at any time. Among the many emerging mobility services, Multiple Passenger Ridesharing and its variants look the most promising. However, challenges arise in implementing these systems while accounting specifically for time dependencies and time windows that reflect users’ needs, specifically in terms of real-time fleet dispatching and dynamic route calculation. On the other hand, we must consider the feasibility and impact analysis of the many factors influencing the behavior of the system – as, for example, service demand, the size of the service fleet, the capacity of the shared vehicles and whether the time window requirements are soft or tight. This paper analyzes - a Decision Support System that computes solutions with ad hoc heuristics applied to variants of Pick Up and Delivery Problems with Time Windows, as well as to Feasibility and Profitability criteria rooted in Dynamic Insertion Heuristics. To evaluate the applications, a Simulation Framework is proposed. It is based on a microscopic simulation model that emulates real-time traffic conditions and a real traffic information system. It also interacts with the Decision Support System by feeding it with the required data for making decisions in the simulation that emulate the behavior of the shared fleet. The proposed simulation framework has been implemented in a model of Barcelona’s Central Business District. The obtained results prove the potential feasibility of the mobility concept.Postprint (published version

Modelling Fresh Strawberry Supply "From-Farm-to-Fork" as a Complex Adaptive Network

 The purpose of this study is to model and thereby enable simulation of the complete business entity of fresh food supply. A case narrative of fresh strawberry supply provides basis for this modelling. Lamming et al. (2000) point to the importance of discerning industry-specific product features (or particularities) regarding managing supply networks when discussing elements in "an initial classification of a supply network" while Fisher (1997) and Christopher et al. (2006, 2009) point to the lack of adopting SCM models to variations in products and market types as an important source of SCM failure. In this study we have chosen to move along a research path towards developing an adapted approach to model end-to-end fresh food supply influenced by a combination of SCM, system dynamics and complex adaptive network thinking...

Bridging the gap between weak-demand areas and public transport using an ant-colony simulation-based optimization

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Shared autonomous vehicle services: A comprehensive review

© 2019 Elsevier Ltd The actions of autonomous vehicle manufacturers and related industrial partners, as well as the interest from policy makers and researchers, point towards the likely initial deployment of autonomous vehicles as shared autonomous mobility services. Numerous studies are lately being published regarding Shared Autonomous Vehicle (SAV) applications and hence, it is imperative to have a comprehensive outlook, consolidating the existing knowledge base. This work comprehensively consolidates studies in the rapidly emerging field of SAV. The primary focus is the comprehensive review of the foreseen impacts, which are categorised into seven groups, namely (i) Traffic & Safety, (ii) Travel behaviour, (iii) Economy, (iv) Transport supply, (v) Land–use, (vi) Environment & (vii) Governance. Pertinently, an SAV typology is presented and the components involved in modelling SAV services are described. Issues relating to the expected demand patterns and a required suitable policy framework are explicitly discussed

An adaptive route choice model for integrated fixed and flexible transit systems

Over the past decade, there has been a surge of interest in the transport community in the application of agent-based simulation models to evaluate flexible transit solutions characterized by different degrees of short-term flexibility in routing and scheduling. A central modeling decision in the development of an agent-based simulation model for the evaluation of flexible transit is how one chooses to represent the mode- and route-choices of travelers. The real-time adaptive behavior of travelers is intuitively important to model in the presence of a flexible transit service, where the routing and scheduling of vehicles is highly dependent on supply-demand dynamics at a closer to real-time temporal resolution. We propose a utility-based transit route-choice model with representation of within-day adaptive travel behavior and between-day learning where station-based fixed-transit, flexible-transit, and active-mode alternatives may be dynamically combined in a single path. To enable experimentation, this route-choice model is implemented within an agent-based dynamic public transit simulation framework. Model properties are first explored in a choice between fixed- and flexible-transit modes for a toy network. The framework is then applied to illustrate level-of-service trade-offs and analyze traveler mode choices within a mixed fixed- and flexible transit system in a case study based on a real-life branched transit service in Stockholm, Sweden.Comment: 33 pages, 9 figures, preprin

An interrupted transmission? Processes of CCTV implementation and the impact of human agency

This paper examines the processes that bring about the creation of new public-space CCTV schemes. Through an appraisal of the grounded activities of the practitioners who make decisions over CCTV, the role of agency is identified as a particularly strong, yet relatively neglected, influence on its implementation. Moreover, beyond dichotomised notions of central structures and local agency, an understanding is developed of the complex interaction between the individual actors involved in CCTV dissemination and the political context in which they operate. In doing so, public policy is identified as the vehicle through which camera surveillance systems become installed and disseminated throughout public space. Moreover, these various forces of structure and agency become filtered through identifiable networks of policy-makers, comprising 'responsibilised' actors who oversee the deployment of CCTV. This analysis is used to revisit a range of administrative and theoretical understandings of surveillance, including: citations of CCTV as an evaluated response to crime; the attribution of power- and interest-based agendas to its implementation; and accounts which locate CCTV expansion within various evolving societal processes. Drawing on qualitative fieldwork data gathered during doctoral research, the paper considers the activities of practitioners at a local level and identifies crucial contexts, drivers and negotiations on which expanding surveillance is contingent. Ultimately, it is argued that the process of CCTV installation ? from conception to material implementation ? is disrupted and mediated by a range of micro-level operations, obligations, processes, managerial concerns (particularly conflict resolution and resource issues), structures and agency, and the indirect influence of central government. These not only arbitrate over whether the CCTV becomes installed, but also generate a range of additional uses for the cameras, many of which are performed before they are even switched on. This emphasises the need to consider the processes that enable and constrain the actions of those making decisions over CCTV and demonstrates how no single interest becomes solely participant in the deployment of surveillance. Finally, because of the centrality and contingency of both human agency and the structural contexts in which it operates in determining the installation of CCTV, questions arise concerning the importance of integrative sociological theories in understanding the deployment of surveillance