Abstract

This work investigates the applicability of identification methods to the suspension parameters of a TGV multi-body model. The aim is to adjust the model to the real system by estimating the suspension parameters from measured vehicle response data. Due to the nonlinear behavior of the system the time-domain based model updating has been chosen. It requires the definition and minimization of a misfit function in the time domain describing the distance between model and measurement. The fastest convergence is obtained by the use of gradient methods requiring the calculation of the derivatives of the misfit function relative to every parameter. Since the calculation from finite differences is time consuming and less accurate the gradients are calculated from the adjoint method. The application to a simplified bogie model with known mathematical description allows the identification of its suspension parameters. The presence of local minima in the misfit function of the TGV model requires the use of global optimization methods. The simulated annealing and the genetic algorithm method give important reductions of the misfit function and improved parameter estimations. In following work this information could be used for further applications like the condition monitoring.; Ce travail étudie l’applicabilité des méthodes d’identification aux paramètres de la suspension d’un modèle multi-corps du TGV. L’objectif est de caler le modèle par rapport au système réel par une estimation des paramètres de la suspension en utilisant la réponse du véhicule mesuré. A cause du comportement nonlinéaire du système la méthode temporelle de recalage a été choisie. Elle nécessite la définition et minimisation d’une fonction coût qui décrit la distance entre le modèle et la mesure. La convergence la plus rapide est obtenue avec des méthodes gradient qui demandent le calcul des dérivés de la fonction coût par rapport á chaque paramètre de la suspension. Comme le calcul par des différences finis est coûteux et moins précis la méthode adjoint a été implémentée. L’application à un modèle simplifié d’un bogie avec une description mathématique connue permet d’identifier les paramètres de la suspension. La présence des minima locaux dans la fonction coût du modèle TGV nécessite l’utilisation des méthodes globales. Le recuit simulé et l’algorithme génétique donnent des réductions importantes de la fonction coût et des estimations pour les paramètres du modèle TGV. Dans des travaux ultérieurs, ces informations pourraient être utilisées pour d’autre application comme le « condition monitoring ».

Abstract

RelStat12, 12th Annual International Conference on Reliability and Statistics in Transportation and Communications, Riga, LETTONIE, 17-/10/2012 - 20/10/2012; Along a transit line, vehicle traffic and passenger traffic are jointly subject to variability in travel time and vehicle load hence crowding. The paper provides a stochastic model of passenger physical time and generalized time, including waiting on platform and in-vehicle run time from access to egress station. Five sources of variability are addressed: (i) vehicle headway which can vary between the stations provided that each service run maintains its rank throughout the local distributions of headways; (ii) vehicle order in the schedule of operations; (iii) vehicle capacity; (iv) passenger arrival time; (v) passenger sensitivity to quality of service. The perspective of the operator, which pertains to vehicle runs, is distinguished from the user's one at the disaggregate level of the individual trip.

Abstract

It is increasingly recognized that travel time reliability is important to travellers and goods, and hence there is an increasing demand to include reliability in the evaluation and appraisal of transport projects and programs, as a separate factor in its own right. A number of the policy options already in use as congestion mitigation policies have also positive impacts on the travel time reliability. It is therefore important to evaluate impacts of any remedial action separately both for average travel time (congestion) and for variability of that travel time (reliability). The impacts are generally assessed with an observational before/after study. As many things, independent from the system to be assessed, change between the periods before and after the installation of the system, observational before/after studies take also into account a reference site, where the effect of these changes is identified. In a previous paper Bhouri and Aron, (2013) presented the reliability impacts of a managed lane case consisting in a Dynamic Hard Shoulder Running (HSR) during rush hours on a French urban motorway. The study was conducted by comparing reliability indicators based on data collected in 2002 before the implementation of the system and in 2006 after this implementation. Jacques Chirac, former president of France, launched in 2003 an important campaign for road safety and against speeding. This modified the travel time distribution, differently according to the lane. As reliability is based on the percentiles (and not only on averages), it was necessary, in order not to confound the effect of this campaign with the HSR effect, to develop the observational before/after study method for determining that time effect by level of travel time: to do this, the before and after travel time distributions of the reference site are established, then their difference is analyzed as a function of the travel time, taking into account the percentiles. This method and the results are presented in this paper. Document type: Conference object

Abstract

This article aims to identify some commonalities and differences in intermodal freight in France and Japan, focusing on urban zones. This comparison puts into perspective two spatial situations linked with land pressure. It helps us identify opportunities for knowledge transfer of best practices for the promotion of modal shift and for land use and planning policies that favor intermodal freight. Research works have been carried out on intermodal logistic policies at national scales. However, in urban areas, the use of intermodal services has specific characteristics. Intermodal services are difficult to implement for last mile deliveries, as waterways and railways are used for high volume flows. Nevertheless, during the last decade, an increasing number of projects including intermodal services for the “mile before last” have been set up. Document type: Conference object

Abstract

TRB 2014 - Transportation Research Board 93rd Annual Meeting, WASHINGTON D.C, ETATS-UNIS, 12-/01/2014 - 16/01/2014; An empirical analysis is conducted on lane changing behavior using a trajectory data set collected at a weaving section in Grenoble (France). A detailed literature review shows that strong empirical understanding of the weaving mechanisms is still lacking. The goal is to investigate the lane changing behavior at a microscopic level. Data collection distinguished lane changes from the main road and those towards the main road. Descriptive empirical analysis examines the positions of the lane changes and the corresponding accepted gaps. Results show that under heavy congested traffic conditions the weaving vehicles tend to change lane as soon as possible after the start of the weaving section. When the traffic conditions are fluid, the weaving vehicles coming from the main road tend to change lane earlier than the weaving vehicles coming from the auxiliary lane. Moreover, weaving vehicles coming from the auxiliary lane accept smaller gaps and headways than the weaving vehicles coming from the main road. Our findings are questioning some results of previous works using micro-simulation to study weaving sections. As the weaving vehicles change lane at the beginning of the studied weaving section, our findings ask whether the length of the weaving section is a key variable to estimate its capacity. Our findings raise also some questions about the relevance of the gap acceptance theory to model lane changes at weaving sections. But further research are needed to asses these hypothesis.

Abstract

Managed lanes operations refer to multiple strategies for recurring congestion control by increasing the road capacity or adapting its configuration to the demand level. As a result, the evaluation of their impacts usually focuses on congestion or safety-related indicators. However, with the growing prosperity, consumers demand higher quality transport services, for which reliable transport networks are central. This paper is focused on the travel time reliability assessment of a managed lane experience from a French motorway. The paper shows results from the field test experience of the hard shoulder dynamic use on the A4-A86 motorway in the east of Paris. Further to the reliability assessment, the paper focuses on the reliability indicators. It particularly shows the weakness of the skew of the distribution of travel time indicator.; La gestion dynamique des voies fait appel à de multiples stratégies pour maîtriser les congestions récurrentes, ce en accroissant la capacité de la route ou en adaptant sa configuration à la demande. Ces stratégies sont donc logiquement généralement évaluées en termes d'impacts sur la fluidité ou la sécurité du trafic, impacts mesurés par des indicateurs. Cependant, avec la prospérité croissante, les consommateurs demandent une amélioration de la qualité de service pour laquelle la fiabilité des réseaux de transport est centrale. Cette communication porte sur l'évaluation de la fiabilité des temps de parcours résultant d'une expérimentation de gestion dynamique des voies sur une autoroute en France - le tronc commun A4-A86, à l'est de Paris. La bande d'arrêt d'urgence y a été ouverte à la circulation à certaines périodes de la journée. Les résultats de cette expérimentation sont donnés ici ; à la lumière de ces résultats notamment, les indicateurs de fiabilité sont ensuite discutés. On montre en particulier la faiblesse de certains indicateurs fondés sur la largeur ou la dissymétrie de la distribution des temps de parcours. Document type: Conference object

Abstract

International audience; Bus transit plays an important role in commuters' daily life in urban areas. The energy efficiency of bus transit impacts not only on the passengers' travel cost but also the urban environment. The traditional transit vehicles, such as Compressed Natural Gas (CNG) and diesel buses, generate massive Green House Gas (GHG) and pollutants while operating in urban streets. In contrast, zero-emission buses, such as supercharge bus and electric bus, entail environmental friendliness but require huge initial investment for fleet purchase. Conventional bus route design largely ignored the environmental factors. Thus, the air pollutions may be enhanced by the flawed design of bus stop locations because of the frequent and inefficient deceleration and acceleration at stops. In this paper, a multi-period (peak hour and off-peak hour) continuum model will be built to optimize the design of a bus route for different vehicle models (i.e., supercharge bus, electric bus, CNG, and diesel bus). Environmental cost will be explicitly considered. A case study is conducted in Yaan City (China), where the 1 st supercharge bus route is in operation. Comparing with current design, the optimal result indicates that the average stop spacing can be further reduced by up to 13%, and the peak hour headway should be further shorted, which results in less access time and waiting time. Furthermore, we examined our results against those using discrete model to verify accuracy. The results show that the outcomes of continuum and discrete model are in the neighborhood (with an error less than 3%).The proposed model and solution method are demonstrated for practical implementation in urban route design.

Abstract

International audience; Purpose : The focus of this paper is to enhance our observation and knowledge of interurban road freight transport. It explores some possibilities for improving roadside freight surveys, usually used to gather origin-destination data. Methodology : To achieve this, new questions are added to a standard roadside survey form, and the enhanced survey form is tested through two surveys. The new questions relate to currently unobserved variables: the vehicle volume occupied by freight; the method of organisation (double crew, relays) used by the carriers; the existence of speci c logistical imperatives; and drivers' compulsory breaks. Results : The questions on volume constraint and carrier organisation prove to be the most informative. These two questions are thus two promising areas for improvement in roadside freight surveys. The questions about speci c logistical imperatives and driver breaks prove less fruitful. Conclusion : The paper concludes that it is possible, through minor modi cations in data collection protocols, to signi cantly enhance observation quality in road freight transport activity.

Abstract

dvanced Driver Assistance Systems (ADAS) based on video camera tends to be generalized in today's automotive. However, if most of these systems perform nicely in good weather conditions, they perform very poorly under adverse weather particularly under rain. We present a novel approach that aims at detecting raindrops on a car windshield using only images from an in-vehicle camera. Based on the photometric properties of raindrops, the algorithm relies on image processing technics to highlight raindrops. Its results can be further used for image restoration and vision enhancement and hence it is a valuable tool for ADAS.

Abstract

International audience; Currently, over 90% of goods are transported by road terrestrial mode. To progress, companies of Road Freight Transport sector (RFT) are subject to a number of issues, whether economic, regulatory, environmental, societal, occupational health and safety ... The planner has a crucial role in achieving these challenges, it is he who undertakes the construction method of the tours, for the future of the company. Thus he bears a heavy responsibility on his shoulders. Its ability to integrate the company’s constraints and to master the balance between these issues in the construction of tour is vital. However, a list of risks is potentially present and can affect his planning. This lack of vision about risks impact prevents him to achieve his mission. Thus we propose in this article a mean to qualify the tours generated in relation to the issues mentioned but also in terms of potential hazards that could come impair the quality of tours. In this article, we propose an evaluation process of road transport of goods tours and an indicator to measure the robustness of touring.