1,721,280 research outputs found
Rationalization of Freight Flows within the Historic Centers: The Case of Rome
No full textThe chapter focuses on the importance to develop integrated solutions for improving the sustainability and livability of urban area and to implement a demand model system for the assessment of design scenarios. Then, a methodology to rationalize the urban freight flows is presented, and the subsequent its application to the historic area of Rome (Italy) is discussed. In particular, the methodology was used for assessing a new city logistics scenario where a set of measures was proposed to optimize freight flows to shops (in-store purchases) and to end consumers (e-purchases)
Personal Path Choice Modelling in Transit Advisor Tools: Theoretical and Empirical Evidences
No full textCalibrazione aggregata di modelli per la simulazione della domanda merci a scala nazionale
No full textIn this work, the Multi Regional Input-Output (MRIO) model was calibrated using aggregate datasets and applied to assess ex ante the economic impacts due to the implementation of new transportation infrastructures. The models were calibrated using all data available from national and regional statistical sources. The paper also reports an application to the appraisal of new infrastructures in Italy. Two scenarios were assessed: short and long-medium periods
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
Combining reliability, reputation and honesty to enhance QoS on federated computing infrastructures
No full textIn this paper, we suggest an approach aimed at maximising the "global utility"(i.e., QoS) perceived into a large-scale federated computing infrastructures. Our approach computes the node and starts a procedure for the formation of coalitions between them. In particular, it is based on a trust model that allows actors to quantify the trustworthiness of their peers, and on a decentralised procedure that allows the Computing Federation to optimise the QoS. We define the generic SLA-based federated architecture, that is the global QoS offered by the federation, and we describe the theoretical foundation on which our proposal is based. Finally, we illustrate the experimental results which prove that the Global Capital of the Computing Federation improves
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
Shopping and Transport Modes
No full textTraditionally, urban travel demand studies consider work trips as the main constituent of daily trips which consequently attract considerable analytical attention to transport choice and especially modal choice. However, with the increase in traffic-related problems coupled with evolving lifestyles, it has become imperative to focus on trips intended for other purposes including shopping which, in most urban contexts, represents the second most commonly undertaken trips after those for work. The chapter aims to develop an overview of modes used for shopping trips and to highlight the factors which influence a trip maker’s mode choice behaviour according to empirical evidence
City characteristics and logistics measures: synthetic evidences to a pre-guideline in Europe
No full textToday, there is a worldwide focus on setting up a Sustainable Development Strategy to identify and define measures to achieve a continuous long-term improvement in quality of life by creating sustainable communities able to manage and use resources efficiently and effectively, use the ecological and social innovation potential of the economy and, in the end, ensure prosperity, environmental protection and social cohesion. In this context, great importance assumes the urban transport and, in particular, the freight transport. The urban freight transportation impacts can be reduced by implementing different city logistics measures but we need to verify if they strongly penalize the city centres and the commercial activities located there. All the implementable city logistics measures have to point out the impacts generated on the existing distribution schemes used by the urban commercial activities.
However, in this context, the paper, within the field of city logistics sustainability, recalls the overview of measures to be implemented, in a “what if” framework, with strong references to the ex-post assessment carried out in order to support the definition of city logistics scenarios that should have to be evaluated ex-ante by simulation models. The analysis is done in relation to the goals of environmental sustainability to be pursued and the main characteristics of analyzed cities (e.g. population, density). The paper would want to provide a pre-guideline that could be used in an ex-ante assessment methodology in order to identify which measure (or set of measures) works better in a specific city in relation to the goals of environmental sustainability to be pursued
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 general multi-step model for urban freight movements
No full textFreight demand models are one of the key components of the transport plans at the strategic, tactical and operative level. Local authorities need to predict future transport requirements both for passengers and freight so as to plan the development of infrastructures and related human resources. The private sector requires models to predict transport service demand in order to evaluate future needs. This applies both to transport service managers, producers of consumer goods and firms using transport services, as well as manufacturers of commercial vehicles.
One of the greatest difficulties in analysing freight mobility is the identification of decision-makers involved in the process. In the case of freight, there is no sole decision-maker who chooses trip characteristics, but rather a complex set of decision-makers responsible for production, distribution and marketing who, in turn, operate in different field as producers, who have an economic function and dealwith the production of goods, or as consumers, who are freight consumers and become producers of semi-finished goods, destined for the markets and hence towards end-consumers.
In this paper a general multi-step model to simulate urban freight transport is proposed. Then the specification, calibration and validation of the attraction model is reported, performed by means of two different sample and corrected by means of traffic counts.
The proposed freight transport models, for a medium-size city, with a disaggregated approach, can be segmented in different steps some of which have been specificated and calibrated:
* Quantity attraction and distribution models. From the general population data (residents, number of employed, stores) the quantity for each category is calculated that reaches each traffic zone o in one day arriving from each zone d; in this case it is assumed that the decision-maker is the end consumer;
* Acquisition Model (or large scale distribution). From the data on the location of logistic bases, general stores, freight village, etc. it is possible to calculate for a general retailer in zone d the d-w probability of purchasing, in the generic zone w, the goods that are on sale in his/her store;
* Models for the choice of service and vehicle type. The type of vehicle used for each goods class, with the quantity that it transports and the type of service effected by it (one-to-one, one-to-many, many-to-many, many-to-one) is obtained by means of a logistic model;
* Path choice model. For each type of service the probability of each path is evaluated
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