1,721,077 research outputs found
Dynamic travel demand estimation and prediction methods
No full textAvailability of accurate trip demand estimates plays a key role for both long term and short term traffic planning as well as for on-line applications of intelligent management strategies that require reliable forecasts of traffic demand so that usersâ response to varying flow conditions, both observed and communicated, in different locations and in different time intervals, can be properly taken into account and anticipated. To guarantee consistency with respect to temporal and spatial dimensions, traffic demand estimates and predictions must reflect both time variability and network patterns. This calls for a problem known in literature as Dynamic Demand Estimation problem (DDEP); it can be formulated as an off-line problem for medium to long term planning and design, or as an on-line problem for real time ATMS/ATIS applications. In both cases, traffic dynamics are dealt with at network level. Nowadays, demand data derive from advanced traffic surveillance systems based on the collection of several heterogeneous traffic measurements both in fixed locations and over specific corridors or paths. Such recent technology developments suggest new promising and challenging chances, not fully addressed yet. In this chapter, the main formulations of the demand estimation and prediction problem are described first, along with the related literature review for both the off-line and the on-line approach; then, some relevant study-cases are illustrated; finally, future perspectives relying on new emerging technological opportunities are envisaged
Data accuracy on automatic traffic counting: The SMART project results
No full textIn this paper the results of an experimental
survey on traffic monitoring devices, named SMART
Project, are presented. Aim of the project was to define
the requirements to be applied to traffic technologies to
match specific applications. The project involved the
construction of a test site on a main road, where seven
different traffic monitoring systems were installed. A 1 year
survey was carried out to assess technologies response to
environmental and mechanical solicitations. A reference
system specifically devoted to check and validate the
devices under test was designed for the project. Test
procedures were also developed to control the results
achieved. The outcomes accomplished for vehicles counting
are described in details in the essay hereunder
A surrogate approach for the global optimization of signal settings and traffic assignment problem
No full textWe extend a `surrogate problem' approach that is developed for a
class of stochastic discrete optimization problems so as to tackle
the global signal settings and traffic assignment combined
problem. We compare a stochastic method based on the surrogate
approach, called Surrogate Method (SM), with a Projected
Gradient Algorithm (PGA), which uses the Armijo rule for the step
size estimation routine. Numerical experiments conducted on a test
network show that the surrogate method converges to a really
small area and it finds much more efficient solutions
Strategies and Measures for Sustainable Urban Transport Systems
Full text linkAbstractIncreasing sustainability of urban transport systems is a crucial objective of all strategic plans both at national and European level. Different strategies and measures can be adopted to improve the efficiency of transport systems, according to a large set of factors that can affect the results of the implemented actions. A comprehensive study has been carried out in order to define a methodology able to define effective and efficient strategies and measures, allowing to increase the sustainability level of different kinds of cities, from small-medium sized to large metropolitan areas. The methodology has been tested on a group of 50 Italian cities, whose characteristics have been analysed through an initial set of more than 200 indicators. Three main groups of indicators have been taken into account: State indicators, Sustainability indicators, Policy indicators. The main aim has been to identify existing relationships between Sustainability and Policy indicators for cities showing commonalities in terms of State indicators. A correlation analysis allowed to identify 53 relevant indicators from the initial set of 200, while a cluster analysis, based on a hierarchical model, allowed to group the cities into five different groups, according to their population size and density. Correlations between relevant indicators have also been analysed within each group, while linear regression models have allowed to describe some functional relations between Policy and Sustainability indicators. A benchmarking exercise has allowed to identify strategies and measures adopted by the best performers within each group, hence defining possible paths to a better sustainability level for the remaining cities. Finally, recommendations for a correct urban mobility planning procedures have been produced
An urban traffic flow model to capture complex flow interactions among lane groups for signalized intersections
No full textThis paper presents a traffic flow model, based on cell transmission concept, to capture urban traffic dynamics taking into account complex flow interactions among lane groups at upstream of signalized intersections. This model is a simple and versatile simulation framework designed to simulate, at macroscopic level, more realistically the dynamic interaction of queues among neighboring lanes and intersections for large scale urban network. Model validation has been undertaken by comparing with Vissim results obtained in different scenarios that have been tested
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