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See detailA combined parking and carpooling policy: the case of the University of Luxembourg
Sprumont, François UL; Viti, Francesco UL; Ouzdi, Youssef UL

Scientific Conference (2015, May 29)

With 2586km2, Luxembourg is the 7th European smallest country in Europe. Despite its small size this country is facing important mobility challenges. Out of the 380 000 available jobs in the country ... [more ▼]

With 2586km2, Luxembourg is the 7th European smallest country in Europe. Despite its small size this country is facing important mobility challenges. Out of the 380 000 available jobs in the country, nearly 43% of them are occupied by cross borders workers. These 165 000 cross borders traveling every day from France, Belgium and Germany generate an important pressure on the transport infrastructures. Because 89% of the cross-borders workers and 74% of the resident workers commute by car, the road system, at peak hours, reaches saturation. In order to decrease the pressure (in term of commuting flow, residential prices, etc.) on Luxembourg City and to reach a more balanced polycentric development across the country the development of Belval has been decided by the government. This new-town which is located 20km south-west of Luxembourg-City will attract economic activity and residential units. The University of Luxembourg will be one of institutions relocating most of its infrastructure in Belval. Without any doubts, this workplace relocation will greatly affect the University staff commuting mobility. In accordance to any public institution or large enterprise in this country, the University is more and more committed to reduce the carbon footprint related to the staff and students commuting behavior. The MODU (national sustainable mobility strategy) defines strong modal split objectives and the number of parking spaces available for the university on Belval site will rely on this national objective. So far, few scientific contributions analyzed the accessibility variation for car and Public Transport (PT) on important worker’s’ population considering relocation actions of this size. GIS tools and visualization techniques will permit to quantify the car and public transport accessibility vari ation due to the University move to Belval. The scientific contribution of this article lies in the relation between the car & PT accessibility and the development of Travel Demand Management (TDM) measures. Indeed, an innovative Parking Management Scheme (PMS) integrating car & PT accessibility to the new campus as well as carpooling use among the staff members will be presented. Our aim is to develop a mobility credit scheme system where users could use points to park their car or use the public transport system. Soft modes might collect additional points that could serve to get gifts or even cash back. Indeed, the objective is to reach a pragmatic parking policy that lead Single Occupancy Vehicle (SOV) to shift, first, to soft modes, then, to public transport and finally to carpooling. The key is the relation between the different travel modes and their existing incentives or disincentives. This approach might help other major private or public institutions to define optimum subsidy strategies regarding their parking and staff’s public seasonal ticket costs. [less ▲]

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See detailSystematic assessment of local & global signal control policies: A methodological perspective
Cantelmo, Guido UL; Viti, Francesco UL; Rinaldi, Marco UL et al

in Proceedings of 2015 International Conference on Models and Technologies for Intelligent Transportation Systems, MT-ITS 2015 (2015)

Traffic control performance on networks depends on the flow response to the policy adopted, which in turn contributes to determine the optimal signal settings. This paper focuses on the relationship ... [more ▼]

Traffic control performance on networks depends on the flow response to the policy adopted, which in turn contributes to determine the optimal signal settings. This paper focuses on the relationship between local and network wide traffic control policies within the combined traffic control and assignment problem. Through a full exploration of the solution space, an in depth cross comparison is performed between the well-known local policies P0 and Equisaturation, versus the global policies Maximum Throughput and Minimum Delay, to verify how the two local policies approximate the optimal settings for signalized intersections. Realistic traffic dynamics, such as congestion, multiple controllers and spillback are considered, to empirically determine the conditions under which the local policies are able to approximate global performances. After presenting the different local and global control policies, experiments are performed on simple toy networks. The complexity of the underlying network and, therefore, of the problems' boundary conditions is then increased, allowing us to showcase how the different metrics perform in different situations. Finally, conclusions on the results are drawn. © 2015 BME. [less ▲]

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See detailAnalysis to Feature-Based Video Stabilization/Registration Techniques within Application of Traffic Data Collection
Tafaghod Sadat Zadeh, Seyed Mojtaba UL; Viti, Francesco UL

in Proceedings of the ICMV Conference (2015)

Machine vision is rapidly gaining popularity in various applications, among others in the field of Intelligent Transportation Systems. In particular, potential advantages are foreseen by the exploitation ... [more ▼]

Machine vision is rapidly gaining popularity in various applications, among others in the field of Intelligent Transportation Systems. In particular, potential advantages are foreseen by the exploitation of Aerial Vehicles (AV) in delivering a superior view on traffic phenomena. However, vibration on AVs makes it difficult to extract moving objects on the ground. To partly overcome this issue, image stabilization/registration procedures are adopted to correct and stitch multiple frames taken of the same scene but from different positions, angles, or sensors. In this study, we aim to examine the impact of multiple feature-based techniques for video stabilization using different scenarios. In the proposed framework, SURF detector outperformed the others in terms of time efficiency and output similarity. [less ▲]

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See detailEditorial: Challenges, specificities and commonalities of transport research and policy within the BENELUX countries–the case of Luxembourg
Caruso, Geoffrey UL; Gerber, Philippe; Hesse, Markus UL et al

in European Journal of Transport and Infrastructure Research (2015), 15(4), 501-505

In the recent years, the Grand Duchy of Luxembourg has emerged as a new player in research as part of a strategy to foster its knowledge for both economical and societal developments. In the transport ... [more ▼]

In the recent years, the Grand Duchy of Luxembourg has emerged as a new player in research as part of a strategy to foster its knowledge for both economical and societal developments. In the transport research field, the University of Luxembourg (created in 2003) with its Geography and Spatial Planning Institute (created in 2007) and its Transport Engineering group (created in 2012) joined forces with the public research institution LISER (previously CEPS-INSTEAD) to organize the 2013 Transport Research Day of the BIVEC. Looking backward to the event while preparing this editorial, we can see it actually played a kick-off role for the international diffusion of Luxembourg research on transport and related land-use issues, and was a good occasion to shed lights on Luxembourg specificities and commonalities within the Benelux, which we like to stress in this editorial. [less ▲]

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See detailWorkplace Relocation and Mobility Changes in a Transnational Metropolitan Area: The Case of the University of Luxembourg
Sprumont, François UL; Viti, Francesco UL; Caruso, Geoffrey UL et al

in Transportation Research Procedia (2014, December), 4

The aim of this paper is to study the utility variation related to the commuting mobility of University staff members due to their future workplace relocation. During the year 2012, a travel survey was ... [more ▼]

The aim of this paper is to study the utility variation related to the commuting mobility of University staff members due to their future workplace relocation. During the year 2012, a travel survey was completed by a total of 397 staff members, representing 36.4% of the university employees, who filled in a questionnaire which revealed complex decision making patterns due to the special traveling scenario involving four countries at once. A Multinomial Logit model has been used to anticipate the impact of university relocation from the capital city to a developing area in the south of the country which will happen between 2015 and 2018 and that will affect most of the employees. The effects of several Travel Demand Management measures are discussed based on the analysis of alternative scenarios [less ▲]

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See detailAssessing partial observability in network sensor location problems
Viti, Francesco UL; Rinaldi, Marco; Francesco, Corman et al

in Transportation Research. Part B : Methodological (2014), 70

The quality of information on a network is crucial for different transportation planning and management applications. Problems focusing on where to strategically extract this information can be broadly ... [more ▼]

The quality of information on a network is crucial for different transportation planning and management applications. Problems focusing on where to strategically extract this information can be broadly subdivided into observability problems, which rely on the topological properties of the network, and flow-estimation problems, where (prior) information on observed flows is needed to identify optimal sensor locations. This paper contributes mainly to the first category: more specifically, it presents a new methodology and an intuitive metric able to quantify the quality of a solution in case of partial observability, i.e. when not all flow variables are observed or can be uniquely determined from the observed flows. This methodology is based on existing approaches that can efficiently find solutions for full observability (i.e., the set of sensors needed to make the system fully determined), and exploits only the algebraic relations between link, route and origin-destination flow variables to quantify the information contained in any arbitrary subset of these variables. The new metric allows, through its adoption within simple search algorithms, to efficiently select sensor locations when the number of available sensors is limited by, for example, budget constraints and is less than the number needed to guarantee full observability. The chosen positions aim at selecting those locations that contain the largest information content on the whole network. This is an important contribution in this field, since even in small sized networks the solution for full observability requires an exceedingly large amount of sensors. The assessment of partial observability solutions, based on explicit route enumeration, allows one to categorize families of full observability solutions, and shows that these contain different information potential. This way, it is possible to rank solutions requiring a lower number of sensors while containing the same information content. We tested this new methodology both on toy networks, in order to analyse the properties of the metric and illustrate its logic, and to explain and test heuristic search algorithms for optimal sensor positioning on a real-sized network. Analysis of partial observability solutions shows that the basic search algorithms succeed in finding the links that contain the largest deal of information in a network. [less ▲]

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See detailA Joint Day-to-Day Mode and Within-Day Departure Time Choice Model for the Analysis of Dynamic Ridesharing
Viti, Francesco UL; Corman, Francesco

Scientific Conference (2014, June 19)

Sharing travels is an effective way to increase car occupancy rates and to reduce the total number of cars for the same distances travelled. A potentially attractive service based on the sharing concept ... [more ▼]

Sharing travels is an effective way to increase car occupancy rates and to reduce the total number of cars for the same distances travelled. A potentially attractive service based on the sharing concept is dynamic ridesharing (DRS), where a service provider matches up driver and passenger with similar itineraries and time schedules with an automated program. To analyse how modal shift from single passenger use of the car to high occupancy one can be realized and what are the demand management solutions that can effectively be recommended, we deal with a theoretically interesting basic model structure of a single-link case, in which we study the complex interaction of multiple factors involved in the dynamic ridesharing problem, and the joint sensitivity to the most relevant parameters involved in this behavioural process. The main contribution of this study is therefore a unified framework that is able to model the dynamics of the departure time, characterized as a within-day process, while keeping the mode choice as a day-to-day process, and characterizing explicitly the matching process of DRS. [less ▲]

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See detailAn adaptive flow anticipatory control using daily iterative learning in urban traffic networks
Huang, Wei; Tampere, Chris M.J.; Viti, Francesco UL

Scientific Conference (2014, June)

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See detailA TWO-STEP APPROACH FOR THE CORRECTION OF THE SEED MATRIX IN THE DYNAMIC DEMAND ESTIMATION
Cantelmo, Guido UL; Viti, Francesco UL; Tampère, Chris M.J. et al

in Transportation Research Record: Journal of the Transportation Research Board (2014), 2466

In this work deterministic and stochastic optimization methods are tested for solving the Dynamic Demand Estimation problem. All the adopted methods demonstrate the difficulty in reproducing the correct ... [more ▼]

In this work deterministic and stochastic optimization methods are tested for solving the Dynamic Demand Estimation problem. All the adopted methods demonstrate the difficulty in reproducing the correct traffic regime, especially if the seed matrix is not sufficiently close to the real one. Therefore, in this paper a new and intuitive procedure to specify an opportune starting seed matrix is proposed: it is a two-step procedure based on the concept of dividing the problem into small-size problems, focusing on specific OD pairs in different steps. Specifically, the first step focuses on the optimization of a subset of OD variables (the ones who generate the higher flows or the ones who generate the bottlenecks on the network). In the second step the optimization works on all the OD pairs, using as starting matrix the matrix derived from the first step. In this way is possible to use a more performance optimization method for every step, improving the performance of the method and the quality of the result with respect to the classical “one-step” approach. The procedure has been tested on the real network of Antwerp, Belgium, demonstrating its efficacy in combination with different optimization methods. [less ▲]

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See detailDynamic Origin-Destination Matrix Estimation on Large-Scale Congested Networks Using A Hierarchical Decomposition Scheme
Frederix, Rodric; Viti, Francesco UL; Tampere, Chris M.J.

in Journal of Intelligent Transportation Systems (2014), 18(1), 51-66

Despite the ever increasing computing power, dynamic Origin-Destination (OD) estimation in congested networks remains troublesome. In previous research, we have shown that an unbiased estimation requires ... [more ▼]

Despite the ever increasing computing power, dynamic Origin-Destination (OD) estimation in congested networks remains troublesome. In previous research, we have shown that an unbiased estimation requires the calculation of the sensitivity of the link flows to all Origin Destination flows, in order to incorporate the effects of congestion spillback. This is however computationally infeasible for large-scale networks. To overcome this issue, we propose a hierarchical approach for off-line application that decomposes the dynamic OD estimation procedure in space. The main idea is to perform a more accurate dynamic OD estimation only on subareas where there is congestion spillback. The output of this estimation is then used as input for the OD estimation on the whole network. This hierarchical approach solves many practical and theoretical limitations of traditional OD estimation methods. The main advantage is that different OD estimation method can be used for different parts of the network as necessary. This allows applying more advanced and accurate, but more time consuming methods only where necessary. The hierarchical approach is tested on a study network and on a real network. In both cases the proposed methodology performs better than traditional OD estimation approaches, indicating its merit. [less ▲]

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See detailImproving the efficiency of repeated dynamic network loading through marginal simulation
Corthout, Ruben; Himpe, Willem; Viti, Francesco UL et al

in Transportation Research. Part C : Emerging Technologies (2014), 41

Currently, the applicability of macroscopic Dynamic Network Loading (DNL) models for large-scale problems such as network-wide traffic management, reliability and vulnerability studies, network design ... [more ▼]

Currently, the applicability of macroscopic Dynamic Network Loading (DNL) models for large-scale problems such as network-wide traffic management, reliability and vulnerability studies, network design, traffic flow optimization and dynamic origin–destination (OD) estimation is computationally problematic. The main reason is that these applications require a large number of DNL runs to be performed. Marginal DNL simulation, introduced in this paper, exploits the fact that the successive simulations often exhibit a large overlap. Through marginal simulation, repeated DNL simulations can be performed much faster by approximating each simulation as a variation to a base scenario. Thus, repetition of identical calculations is largely avoided. The marginal DNL algorithm that is presented, the Marginal Computation (MaC) algorithm, is based on first order kinematic wave theory. Hence, it realistically captures congestion dynamics. MaC can simulate both demand and supply variations, making it useful for a wide range of DNL applications. Case studies on different types of networks are presented to illustrate its performance. [less ▲]

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See detailModels and Technologies for Intelligent Transportation Systems: new challenges and metaheuristic solutions for large-scale network applications
Viti, Francesco UL; Tampere, Chris M.J.

in Journal of Intelligent Transportation Systems (2014), 18(1), 1-4

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See detailDynamic modeling of VISSIM's critical gap parameter at unsignalized intersections
Viti, Francesco UL; Wolput, Bart; Tampere, Chris M.J. et al

in Transportation Research Record: Journal of the Transportation Research Board (2014), 2395

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See detailEvaluation of intervention strategies for a road link in the Netherlands
Adey, Bryan Tyrone; Lethanh, Nam; Hartmann, Andreas et al

in Built Environment Project and Asset Management (2014), 4(2), 180-198

Purpose – The purpose of this paper is to investigate the use of the impact hierarchy and the optimization model to determine the optimal intervention strategy for a road link composed of multiple objects ... [more ▼]

Purpose – The purpose of this paper is to investigate the use of the impact hierarchy and the optimization model to determine the optimal intervention strategy for a road link composed of multiple objects. The paper focusses on the results of a case study of intervention project on A20 road link in Rotterdam, the Netherlands. Design/methodology/approach – The study was a case study research. It describes briefly the impact hierarchy and its link to the optimization model, and then focussed on analyzing the results obtained from running the model. In order to understand the influence of various factors affecting the results of optimization, sensitivity analysis was performed. Findings – The proposed hierarchy is suitable to be used to support the determination of optimal intervention strategies (OISs) for public road. From the case study, it was also realized that optimal intervention strategy can be changed due to not only intervention costs incurred by the owner, but also due to the setup of traffic configuration during the execution of interventions since the impacts incurred to users, directly affected public, and indirectly affected public are significantly different from one traffic configuration to the others. The optimal intervention strategy also depends greatly on the factors of deterioration during the operation of the infrastructure objects. Research limitations/implications – In the impact hierarchy, some impact factors are difficult to be quantified, e.g., the long-term economic impacts on the region where having intervention projects. The use of only exponential function for impacts could be oversimplified the actual behavior of the impacts. Other functional form should be investigated to be used within the framework of the optimization model. Practical implications – The proposed hierarchy and the optimization model could be used in practical situation for determination of OISs for multiple objects within a road link. Originality/value – This paper contributes to the body of knowledge of stakeholder analysis in the field of infrastructure asset management. It also gives a guideline and tool for infrastructure administrators to select the OISs for their infrastructure network. [less ▲]

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See detailQuantifying partial observability in network sensor location problems
Viti, Francesco UL; Rinaldi, Marco; Corman, Francesco

Scientific Conference (2013)

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See detailCalibration of a microscopic simulation model for emission calculation
Li, Jie; Van Zuylen, Henk J.; Chen, Yusen et al

in Transportation Research. Part C : Emerging Technologies (2013), 31

Emissions by road traffic can be reduced by optimising traffic control. The impact of this optimisation on emission can be analysed ex ante by simulation. The simulation programs used for this analysis ... [more ▼]

Emissions by road traffic can be reduced by optimising traffic control. The impact of this optimisation on emission can be analysed ex ante by simulation. The simulation programs used for this analysis should be valid with respect to the traffic characteristics that determine the emissions. Thus calibration of the parameters is a prerequisite. In most cases, volumes, travel times and queues are used to calibrate simulation models, rather than detailed driving characteristics such as speed and acceleration patterns. However, these driving behaviour parameters determine the vehicular emissions to a great extent. A study was carried out in which the driving behaviour parameters in a microscopic simulation model (VISSIM) were calibrated using real trajectories collected by image processing at an intersection in Rotterdam. The sensitivity of the simulation results for driving behaviour parameters was investigated. The most influential parameters were identified and adjusted to ensure that the simulation results were consistent with the observed traffic and could provide valid estimations of the total production of emissions. [less ▲]

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See detailA Null-Space metric for the analysis of partial network observability in sensor location problems
Rinaldi, Marco; Viti, Francesco UL; Corman, Francesco

Scientific Conference (2013)

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See detailDynamic OD estimation in congested networks: theoretical findings and implications in practice
Frederix, Rodric; Viti, Francesco UL; Tampere, Chris M.J.

in Transportmetrica (2013), 9(6), 494-513

In this study we analyse the impact of congestion in dynamic origin–destination (OD) estimation. This problem is typically expressed using a bi-level formulation. When solving this problem the ... [more ▼]

In this study we analyse the impact of congestion in dynamic origin–destination (OD) estimation. This problem is typically expressed using a bi-level formulation. When solving this problem the relationship between OD flows and link flows is linearised. In this article the effect of using two types of linear relationship on the estimation process is analysed. It is shown that one type of linearisation implicitly assumes separability of the link flows, which can lead to biased results when dealing with congested networks. Advantages and disadvantages of adopting non-separable relationships are discussed. Another important source of error attributable to congestion dynamics is the presence of local minima in the objective function. It is illustrated that these local minima are the result of an incorrect interpretation of the information from the detectors. The theoretical findings are cast into a new methodology, which is successfully tested in a proof of concept. [less ▲]

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