1,721,165 research outputs found
Introduction to Modelling Multimodal Transit Systems in an ITS Context
No full textTransit network “big data” collecting and processing and bi-directional communication between transit travellers and info centres are emerging as two factors which could improve both transit network planning and design and short-term forecasting of network states for transit operations control and traveller information provision. Several methodological issues connected to the development of models for real-time transit network simulation and forecasting of vehicle occupancy and crowding degree, for supporting such activities, are analysed in this chapter. The main issues concern real-time transit system modelling, dynamic real-time strategy-based path choice and assignment models, individual path choice modelling and, finally, estimation of OD flows and aggregate calibration of model parameters through collected data
A run-based optimal strategy search method in intelligent stochastic transit networks
No full textThis paper deals with the search for a dynamic run-based optimal travel strategy, to be supplied through mobile devices to travelers on a stochastic multi-service transit network, which includes a forecasting system of bus arrival times at stops. The paper first analyses some existing run-based optimal strategy search methods, then a new procedure is proposed and applied. The optimal strategy is obtained as a heuristic solution of a Markovian decision problem (MDP). The hallmarks of the proposal are to use only traveler state spaces (which allows the curse of dimensionality, one of the main problems of optimal policy search, to be reduced) and to use a real-time error distribution of bus travel time forecasts and at-stop bus arrival time forecasts
The schedule-based modeling of transportation system: recent developments
No full textThis paper presents a concise state-of-the-art and some developments of the schedule-based modelling approach for the simulation of transportation systems. The overview on the evolution of the literature in this field is presented by authors considering, at first, theoretical issues and, then, algorithms, software and applications. A greater attention is made to public transport modelling, even if schedule-based models for other transportation systems, like freights, are also investigated
Dynamic optimal travel strategies in intelligent stochastic transit networks
Full text linkThis paper addresses the search for a run-based dynamic optimal travel strategy, to be supplied through mobile devices (apps) to travelers on a stochastic multiservice transit network, which includes a system forecasting of bus travel times and bus arrival times at stops. The run-based optimal strategy is obtained as a heuristic solution to a Markovian decision problem. The hallmarks of this paper are the proposals to use only traveler state spaces and estimates of dispersion of forecast bus arrival times at stops in order to determine transition probabilities. The first part of the paper analyses some existing line-based and run-based optimal strategy search methods. In the second part, some aspects of dynamic transition probability computation in intelligent transit systems are presented, and a new method for dynamic run-based optimal strategy search is proposed and applied
Le tecniche quantitative per la simulazione e l’ottimizzazione: i metodi per la stima diretta della domanda di trasporto
No full textThe schedule-based approach in dynamic transit modelling: a general overview
No full textRecently, beside the traditional frequency-based approach in dynamic modeling of transit networks, a new approach, called schedule-based, has been developed. This approach refers to services in terms of runs, using the arrival/departure times at stops of each vehicle, and allows us to take into account the time evolution of both supply and demand, as well as to obtain the load of each vehicle at each stop. This modeling approach requires a more precise specification of user behavior mechanism and a specific treatment for origin/destination matrices, supply models path choice and assignment models. In this paper the sta-of-the-art of each of these points, with a classification of existing models and the future perspectives of the research is this field, is provided
Modelling Intelligent Multi-Modal Transit Systems
No full textThe growing mobility needs of travellers have led to the development of increasingly complex and integrated multi-modal transit networks. Hence, transport agencies and transit operators are now more urgently required to assist in the challenging task of effectively and efficiently planning, managing, and governing transit networks. A pre-condition for the development of an effective intelligent multi-modal transit system is the integration of information and communication technology (ICT) tools that will support the needs of transit operators and travellers. To achieve this, reliable real-time simulation and short-term forecasting of passenger demand and service network conditions are required to provide both real-time traveller information and successfully synchronise transit service planning and operations control.
Modelling Intelligent Multi-Modal Transit Systems introduces the current trends in this newly emerging area. Recent developments in information technology and telematics have enabled a large amount of data to become available, thus further attracting transport researchers to set up new models outside the context of the traditional data-driven approach. The alternative demand-supply interaction or network assignment modelling approach has improved greatly in recent years and has a crucial role to play in this new context
Advanced Public Transport Systems and ITS: New Tools for Operations Control and Traveler Advising
No full textBi-directional communication among travelers and info center and transport network “big data” collecting and processing seem to be two new factors that can improve the tools that support network short-term forecasting for transit operations control and traveler advising. Some of these tools, with several methodological issues connected to their development, are analyzed over the paper
A doubly dynamic schedule-based assignment model for transit networks
No full textIn order to improve the performances of transit modeling and in particular to assess the effects of the introduction of ITS technologies, which imply substantial changes in user behavior, in the last 10 years transit path choice and assignment models that use a schedulebased approach, instead of the traditional frequency-based one, have been developed. This paper presents a schedule-based path choice model for high-frequency transit networks, which allows us to consider the evolution in time of transit services, both within-day and day-to-day, as well as the day-to-day learning process of attributes by which users choose. On the basis of this path choice model a dynamic process assignment model, both within-day and day-to-day (from which the term "doubly dynamic" derives), was developed and tested on a realistically sized network to verify its applicability for operations planning
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