1,721,099 research outputs found
Stime di capacità dei rami di intersezioni a rotatoria. Analisi sperimentali e valutazioni mediante modelli
No full textLa crescente diffusione delle rotatorie con precedenza all’anello in ambito nazionale richiede un approfondimento
circa la validità dei principali modelli di stima della capacità dei rami presenti nella letteratura
internazionale. L’analisi descritta, anche se limitata ad un singolo caso, si pone come obiettivo la validazione
di tali modelli e la verifica di un processo di stima della capacità basato sull’utilizzo di un modello di microsimulazione.
Tali analisi si riferiscono a dati derivati dall’osservazione sperimentale del fenomeno circolatorio
al nodo.
I risultati ottenuti indicano una prevalente sottostima dei valori di capacità dei rami da parte dei modelli più
comunemente impiegati mentre, grazie alla sua flessibilità e capacità di adattarsi alle caratteristiche peculiari
del nodo, la procedura basata sulla simulazione di traffico è parsa più efficace nella rappresentazione del fenomeno
reale
Applicazione di un modello parzialmente non compensativo sequenziale per la simulazione delle scelte di trasporto delle aziende di produzione
No full textNella presente nota viene proposta l’applicazione del modello parzialmente non compensativo sequenziale basato su soglie di accettabilità (nel seguito indicato come SSA) descritto in Gastaldi M., Rossi R., Vescovi R. (2004) per la simulazione delle scelte di trasporto delle aziende di produzione. In particolare ci si riferisce alle scelte dichiarate nell’indagine di tipo SP effettuate in quattro distretti del Veneto nell’ambito del progetto di ricerca “Logistica e trasporti per i sistemi produttivi locali: metodi e modelli applicati alla realtà produttiva del nord-est padano”.
Gli obiettivi primari del lavoro sono stati da una parte la valutazione della capacità di rappresentazione del modello proposto ed il confronto dei risultati prodotti dal medesimo in fase di simulazione con quelli ottenibili con modelli tradizionali di tipo Logit e dall’altra l’utilizzo dei risultati per l’interpretazione delle scelte dichiarate (lettura, pur semplificata, dei meccanismi che regolano le scelte reali)
An empirical analysis of vehicle time headways on rural two-lane two-way roads
No full textThis paper presents the results carried out from an experimental analysis focused on vehicle time headways distributions with reference to two-lane two-way roads. Our attention has been focused on roads localized in Northern Italy and characterized by different levels of traffic; using data collected by inductive loops and radar sensors, a wide set of observations has been made available. The statistical analysis of these data has allowed to test a set of headway distribution models highlighting their goodness-of-fit with reference to the empirical distributions
Effects of Driver Task-related Fatigue on Driving Performance
No full textIn this study, passive task-related fatigue effects on highway driving were analyzed by means of driving simulator experiments. Ten drivers were asked to drive in various environments in the morning (9:00-11:00 a.m.) and early afternoon (1:00-3:00 p.m.). Mean of Absolute Steering Error and Standard Deviation of Lateral Position, calculated on sub-intervals of 4 minutes, were analysed as response variables. The results confirmed the negative influence of the duration of driving tasks and circadian effects on driving performance, increasing the likelihood of “near misses” and accidents
Analisi dei risultati di un'indagine "SP" sulle scelte di trasporto merci delle aziende di produzione basata sulla teoria degli insiemi fuzzy
No full textIl presupposto essenziale che sta alla base della metodologia proposta nel presente lavoro è la necessità di mantenere nella fase di analisi dei dati raccolti l’incertezza associata alle valutazioni di tipo semantico espresse dai soggetti intervistati in merito alla propensione al cambiamento del servizio di trasporto Intervista di tipo SP). In tale prospettiva per il trattamento di detta incertezza si è cercato di adottare una struttura matematica coerente con la natura dell’incertezza stessa. In particolare ci si riferisce alla teoria della possibilità-necessità
An application of fuzzy sets and possibility theory to the goods transportation choices of manufacturing companies
No full textThe aim of the analysis is to find out a ranking of preference on transportation hypothetical alternatives with reference to the distribution of goods produced in the north-estern Italy manufacturing districts. An SP type survey appeared to be the most appropriate tool to measure the producing companies’ propensity towards alternative transportation services to those currently used. The data gathered were affected by uncertainty: it was analysed using the fuzzy sets and possibility theory that appear to be suitable for dealing with the uncertain nature of the data. The methodology proposed appears to be efficient and simple to implement
Gap-acceptance behavior at roundabouts: experiments on the effect of headway distribution using a driving simulator
No full textAn improvement of a fuzzy three-level model to evaluating transport systems sustainability considering decision-maker's attitude
No full textThe concept of sustainable transport has been widely debated in recent years, given its close links with that of sustainable development, by which it can acquire significance.
This paper proposes a fuzzy theory-based methodological approach that leads to the definition of a summary indicator of sustainability, that can be used to evaluate the sustainability of a given action plan for transportation and land-use systems.
This approach, formalising the “three pillars of sustainability” concept with the theory of fuzzy systems, has the capability to deal with non-homogeneous indicators, maintaining the uncertainty associated with their evaluation and the interrelation between the overlapping dimensions of sustainability.
The paper describes the architecture of the proposed model, paying particular attention to the representation of the indicators using fuzzy sets and to the differences with the previous structure of the model
Logit models incorporating driving styles variablesfor representing gap-acceptance behavior
No full textThe paper proposes an analysis of Logit models for representing gapacceptance
behavior at priority intersection. Differently from other
studies, in this work gap-acceptance data were collected from driving
simulator tests. The effectiveness of the data collected from experiments
with driving simulators is highlighted: the use of driving styles
variables not detectable from direct observations (on site) in driver gapacceptance
models can positively affect the accuracy of operational
analysis (micro simulation, maneuver capacity and LOS assessment)
Empirical Analysis of Vehicle Time Headways and Speeds on Rural Two-Lane, Two-Way Roads
No full textAccurate knowledge of vehicle time headway (TH) and speed distributions is essential in many traffic engineering applications, such as capacity and level-of-service analysis, and in several contexts (operations at road segments, priority junctions, roundabouts, merging maneuvers). Other fields of interest are represented by vehicle generation in traffic microsimulation models and driving simulation applications. This paper presents results from an experimental analysis of vehicle TH and speed distributions on two-lane, two-way roads. The focus is on rural roads in Northern Italy, which are characterized by various levels of traffic and where data were collected by radar sensors. A trendless analysis of observed THs was carried out. Analysis then focused on estimating a well-known TH model, gamma-generalized queuing. Statistical analysis of the available data allowed testing of a set of speed distribution models, highlighting their goodness of fit with reference to empirical distributions. Completing the analysis, bivariate distributions were estimated to represent headway and speed distributions. The traffic parameters considered to affect TH distributions were flow rate and flow composition (percentage of heavy vehicles). Exogenous conditions, such as weather and road geometric futures, were common to all analyzed time periods and cross sections. The final goal of the analysis was to create a picture of the relationship between traffic conditions and speed and headway distributions for a typical road
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