19,931 research outputs found

    The principles of public transport network planning: a review of the emerging literature with select examples

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    This paper highlights for urban planners the key strategies and tactics that can be deployed to improve suburban public transport networks. Introduction The governance and management of public transport systems is an essential component of metropolitan planning and urban management. Most metropolitan strategies in Australia and in other jurisdictions presuppose the provision of public transport. Yet there is often a disconnection between transport plans and land-use schemes. Similarly, metropolitan land-use plans that do integrate with transport plans tend to focus on infrastructure rather than service quality and connectivity. A failure to adequately consider the quality of public transport networks in land-use planning analysis has the potential to produce poor planning outcomes in two key ways. First new land-uses may be inadequately served with public transport services, leading to dependence on alternative travel modes, such as cars. Second, the failure to recognise the significance of well-planned local public transport networks may result in the preclusion of some land-use options. This preclusion may relate to the location of land-uses or their design, such as over-provision of carparking. The continuing debate over whether to address suburban cardependence via land-use change or via transport planning is a case in point. And while the arguments in favour of and against land-use change as a means to overcome car dependence are well known in the planning literature. There is a growing if not yet widely appreciated literature that advocates improvements to public transport network planning and coordination as a means of reducing car dependence. The recognition of improved public transport network planning as a means of reducing car dependence is immensely significant because it offers planners an additional or alternative tool for managing urban transport patterns beyond land-use variation or investment in heavy infrastructure. Urban planning practitioners are not yet well served and informed by the broader public transport planning literature on the advantages of public transport network planning. While there is an extensive literature focusing on the economics and engineering of urban public transport systems the planning literature on the practices that contribute to success in public transport network design and operations is relatively poorly documented. There is also very little literature dedicated to public transport network design within Australian cities which are distinguished by highly centralised radial heavy rail networks with bus or tram networks that are well developed in inner urban zones but less so in the outer suburbs. The remainder of this paper has four objectives for transport planning theory and practice. First the paper reviews the literature on public transport network planning principles; next the paper attempts to formulate these principles in practical terms such that they can be applied to line and network design; third the paper considers further dimensions of network planning, including institutional arrangements and transition points in network design. The paper is intended for three audiences. The first is planning scholars who are involved in debates about public transport. The second is strategic policy officials in planning agencies who are involved in the planning and design of public transport networks. The third audience comprises those involved in development processes and who seek insights into the technical components of public transport network planning. Some caveats are appropriate however. The paper is not seeking to justify public transport network planning. The authors consider that the case for dedicated planning is implicit in the assumption that cities should provide good quality public transport to their residents. The wider case in favour of network planning has been successfully advanced elsewhere. Conversely, the paper is not intended as a directly applicable manual of detailed transport planning practice. While it does offer some insights into the practical public transport network planning task such guidance is better provided by Nielsen et al and Vuchic. Instead the paper highlights for urban planners the key strategies and tactics for that can be deployed to improve suburban public transport networks. Understanding these principles should thus assist urban planners – and urban scholars – to better shape and evaluate urban development processes and patterns

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

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    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

    The crew-scheduling module in the GIST system

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    The public transportation is gaining importance every year basically due the population growth, environmental policies and, route and street congestion. Too able an efficient management of all the resources related to public transportation, several techniques from different areas are being applied and several projects in Transportation Planning Systems, in different countries, are being developed. In this work, we present the GIST Planning Transportation Systems, a Portuguese project involving two universities and six public transportation companies. We describe in detail one of the most relevant modules of this project, the crew-scheduling module. The crew-scheduling module is based on the application of meta-heuristics, in particular GRASP, tabu search and genetic algorithm to solve the bus-driver-scheduling problem. The metaheuristics have been successfully incorporated in the GIST Planning Transportation Systems and are actually used by several companies.Integrated transportation systems, crew scheduling, metaheuristics

    Assessing the Efficiency of Mass Transit Systems in the United States

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    Frustrated with increased parking problems, unstable gasoline prices, and stifling traffic congestion, a growing number of metropolitan city dwellers consider utilizing the mass transit system. Reflecting this sentiment, a ridership of the mass transit system across the United States has been on the rise for the past several years. A growing demand for the mass transit system, however, necessitates the expansion of service offerings, the improvement of basic infrastructure/routes, and the additional employment of mass transit workers, including drivers and maintenance crews. Such a need requires the optimal allocation of financial and human resources to the mass transit system in times of shrinking budgets and government downsizing. Thus, the public transit authority is faced with the dilemma of “doing more with less.” That is to say, the public transit authority needs to develop a “lean” strategy which can maximize transit services with the minimum expenses. To help the public transit authority develop such a lean strategy, this report identifies the best-in-class practices in the U.S. transit service sector and proposes transit policy guidelines that can best exploit lean principles built upon best-in-class practices

    Decentralized Greedy-Based Algorithm for Smart Energy Management in Plug-in Electric Vehicle Energy Distribution Systems

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    Variations in electricity tariffs arising due to stochastic demand loads on the power grids have stimulated research in finding optimal charging/discharging scheduling solutions for electric vehicles (EVs). Most of the current EV scheduling solutions are either centralized, which suffer from low reliability and high complexity, while existing decentralized solutions do not facilitate the efficient scheduling of on-move EVs in large-scale networks considering a smart energy distribution system. Motivated by smart cities applications, we consider in this paper the optimal scheduling of EVs in a geographically large-scale smart energy distribution system where EVs have the flexibility of charging/discharging at spatially-deployed smart charging stations (CSs) operated by individual aggregators. In such a scenario, we define the social welfare maximization problem as the total profit of both supply and demand sides in the form of a mixed integer non-linear programming (MINLP) model. Due to the intractability, we then propose an online decentralized algorithm with low complexity which utilizes effective heuristics to forward each EV to the most profitable CS in a smart manner. Results of simulations on the IEEE 37 bus distribution network verify that the proposed algorithm improves the social welfare by about 30% on average with respect to an alternative scheduling strategy under the equal participation of EVs in charging and discharging operations. Considering the best-case performance where only EV profit maximization is concerned, our solution also achieves upto 20% improvement in flatting the final electricity load. Furthermore, the results reveal the existence of an optimal number of CSs and an optimal vehicle-to-grid penetration threshold for which the overall profit can be maximized. Our findings serve as guidelines for V2G system designers in smart city scenarios to plan a cost-effective strategy for large-scale EVs distributed energy management

    Examination of Regional Transit Service Under Contracting: A Case Study in the Greater New Orleans Region, Research Report 10-09

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    Many local governments and transit agencies in the United States face financial difficulties in providing adequate public transit service in individual systems, and in providing sufficient regional coordination to accommodate transit trips involving at least one transfer between systems. These difficulties can be attributed to the recent economic downturn, continuing withdrawal of the state and federal funds that help support local transit service, a decline in local funding for transit service in inner cities due to ongoing suburbanization, and a distribution of resources that responds to geographic equity without addressing service needs. This study examines two main research questions: (1) the effect of a “delegated management” contract on efficiency and effectiveness within a single transit system, and (2) the effects of a single private firm—contracted separately by more than one agency in the same region—on regional coordination, exploring the case in Greater New Orleans. The current situation in New Orleans exhibits two unique transit service conditions. First, New Orleans Regional Transit Authority (RTA) executed a “delegated management” contract with a multinational private firm, outsourcing more functions (e.g., management, planning, funding) to the contractor than has been typical in the U.S. Second, as the same contractor has also been contracted by another transit agency in an adjacent jurisdiction—Jefferson Transit (JeT), this firm may potentially have economic incentives to improve regional coordination, in order to increase the productivity and effectiveness of its own transit service provision. Although the limited amount of available operation and financial data has prevented us from drawing more definitive conclusions, the findings of this multifaceted study should provide valuable information on a transit service contracting approach new to the U.S.: delegated management. This study also identified a coherent set of indices with which to evaluate the regional coordination of transit service, the present status of coordination among U.S. transit agencies, and barriers that need to be resolved for regional transit coordination to be successful

    Advanced information processing system: The Army fault tolerant architecture conceptual study. Volume 1: Army fault tolerant architecture overview

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    Digital computing systems needed for Army programs such as the Computer-Aided Low Altitude Helicopter Flight Program and the Armored Systems Modernization (ASM) vehicles may be characterized by high computational throughput and input/output bandwidth, hard real-time response, high reliability and availability, and maintainability, testability, and producibility requirements. In addition, such a system should be affordable to produce, procure, maintain, and upgrade. To address these needs, the Army Fault Tolerant Architecture (AFTA) is being designed and constructed under a three-year program comprised of a conceptual study, detailed design and fabrication, and demonstration and validation phases. Described here are the results of the conceptual study phase of the AFTA development. Given here is an introduction to the AFTA program, its objectives, and key elements of its technical approach. A format is designed for representing mission requirements in a manner suitable for first order AFTA sizing and analysis, followed by a discussion of the current state of mission requirements acquisition for the targeted Army missions. An overview is given of AFTA's architectural theory of operation
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