CETE de Lyon

Clermont-Ferrand, France

CETE de Lyon

Clermont-Ferrand, France
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In addition to its harmful economical and social effects, road traffic congestion is a key contributor of emissions of CO 2 and local pollutants. Many traffic management policies could be implemented to tackle it. However, the impacts of those strategies on air quality and greenhouse effect are poorly predicted by classical assessment procedures. Indeed, current assessment tools are based on aggregated traffic data, which fail to capture the dynamic effects of traffic management policies on traffic flow. This article presents an estimation tool capable of measuring all the effects of traffic management policies. It is based on a commonly used dynamic traffic flow model (AIMSUN) combined with different emission models, in order to identify modelling features leading or not to differences in results. Different models combination have been applied and compared for two traffic regulation strategies: a HOV lane dedicated only to buses and taxis created on the leftmost lane of A1 between Charles de Gaulle airport and Paris, and a reduction of speed limits on a section of motorway A86 in the northwest of Paris. Substantial differences in predictions of different emission models are highlighted. They cannot be entirely explained by differences in emission laws. Other insights with regard to traffic representation and emission models' inputs are also investigated to explain them. © 2012 INRETS et Springer-Verlag France.

Bouteille S.,CETE de Lyon | Bouteille S.,University Paris Est Creteil | Fen-Chong T.,University Paris Est Creteil | Dierkens M.,CETE de Lyon | And 3 more authors.
EPJ Web of Conferences | Year: 2010

Sixty samples from three concrete mixes (same components) were prepared and subjected to frost salt scaling cycles. A set of 20 samples from the same mix was tested according to the French standard XP P18-420. Another set was exposed to different chloride concentrations. Different numbers of freeze/thaw cycles were applied to the last set. The mass of scaled-off particles follows a lognormal distribution. Despite high standard deviation, this scaling test enables to separate high resistant from very low resistant concrete. A combined analysis reveals that the scaling and the chloride penetration front are independent from a phenomenological point of view and that the chloride concentration on the exposed surface directly influences the amount of scaled mass according to the typical pessimum effect. These results raise two main questions: is the amount of chloride on the surface solution a direct or indirect parameter and what happens to this pessimum effect if we take into account the scaling test dispersion? © 2010 Owned by the authors, published by EDP Sciences.

Mauduit C.,CETE de Lyon | Vulcano-Greullet N.,DREAL Bourgogne | Coulon N.,CETE de Lyon | Hammoum F.,UNALM | And 4 more authors.
Bulletin des Laboratoires des Ponts et Chaussees | Year: 2013

In light of the damage witnessed on France's road network over these past several winters, network managers and the scientific community have been seeking to understand the phenomena at play in order to prevent against such degradation. The research undertaken between 2006 and 2009 by the "water-freezing" working group as part of LCPC's Fondephy research project has allowed for an in-depth investigation of a few field cases and the generation of leads for future studies regarding the damage mechanisms capable of taking place over both the long and short term. Among these mechanisms, the phenomenon of sliding, recently observed on the Nantes pavement fatigue carrousel, has been noted between wearing course and foundation layer; this finding has altered the generally held perception of pavement operations specific to the overlaying of bituminous layers and may justify a fatigue occurring over the upper part of the pavement, exacerbated at higher temperature. From another perspective, the phenomenon of swelling of frozen asphalt mixes exposed to partial water saturation could also be explored thanks to recent observations during laboratory experiments that had been inspired from soil freezing/thawing test campaigns. This mechanism may give rise to the sudden appearance of potholes at the pavement surface when exposed to winter weather conditions.

Guyot G.,CETE de Lyon | Carrie F.R.,ICEE
WIT Transactions on Information and Communication Technologies | Year: 2012

Following the AZF chemical accident (Toulouse, 2001, 30 dead), a French law was adopted in 2003 that can compel public and private building owners to implement construction work on their buildings to protect occupants against specific accidents. To face the risk of a toxic gas cloud, they may be obliged to adopt a shelter-in-place strategy which mainly consists of identifying a shelter in the building and remaining in this room until the toxic cloud has finally been swept off. In addition to seeking refuge in an airtight room, this strategy called "passive shelter-in-place" also includes closing all external openings and turning off all mechanical ventilation systems and air vents. In order to prove that shelter's air-tightness is sufficient and that the occupants will not be exposed to irreversible effects, simulations are required using for instance the modeling tool named CONFINE. Originally developed by CETE de Lyon, this software is a pressure code able to model the infiltration of a pollutant inside a 3-zone building (shelter, attic and rest of building). This paper aims at giving an overview of CONFINE (governing equations, modelling hypotheses,) and will illustrate its application with examples of shelter-in-place strategy for residential and public buildings. © 2012 WIT Press.

Ovalle C.,École Centrale Nantes | Ovalle C.,University of Santiago de Chile | Frossard E.,Tractebel Engineering | Dano C.,École Centrale Nantes | And 3 more authors.
Acta Mechanica | Year: 2014

Testing the mechanical response of coarse granular materials requires very large and expensive laboratory equipments. During the 1960s, pioneering experimental programs were carried out on several rockfill dam materials, and those results are still a reference for engineers and researchers. However, only few experimental works have been reported to this day, and due to the scarcity of empirical data, the role of the size effect caused by grain crushing is not well known. To improve understanding of this rarely studied issue and the influence of individual particle strength, this paper analyzes the size effect on rock aggregate crushing strength and its connection with the shear envelope of rockfills. The suitability of the 4-parameter Weibull equation to describe size effects on the crushing strength reported in the literature is discussed. Furthermore, a Weibull statistical analysis was carried out for a wide number of experimental results on rock aggregates, where it has been observed that strength decreases with particle size. In parallel, the results of large triaxial tests on homothetic scaled rockfill samples of 250 and 1,000 mm in diameter reveal that the coarser the material, the higher the amount of grain breakage and the lower the shear strength. The impact of size effects obtained from the experiments is analyzed and discussed in terms of the factor of safety of rockfill slope stability. Furthermore, the results are compared with the only existing theoretical method that links the rock aggregate with the strength of the granular assembly. Good agreement between the empirical results and this theoretical method has been confirmed. © 2014 Springer-Verlag Wien.

Taghavi S.M.,ParisTech National School of Bridges and Roads | Carissimo B.,ParisTech National School of Bridges and Roads | Sartelet K.,ParisTech National School of Bridges and Roads | Muller K.,CETE de Lyon | Korsakissok I.,ParisTech National School of Bridges and Roads
HARMO 2010 - Proceedings of the 13th International Conference on Harmonisation within Atmospheric Dispersion Modelling for Regulatory Purposes | Year: 2010

Efficient and flexible transport systems are an important part of the world's economy and thus, quality of life. Nevertheless, road traffic is an important negative factor regarding air quality, noise and land consumption (Zechmeister et al., 2005). Additionally, it poses a threat to plants and animals, and has direct and indirect consequences for human beings. The US EPA highlights 21 toxic substances that can mainly be assigned to road traffic. Some heavy metals are among them (e.g. Pb, Cd, Cu, Sb, or Zn; US Government, 2001). One of the major problems caused by vehicular traffic at local scales is dry and wet atmospheric deposition near roadside, where the geometry of terrain can be very complex. Modeling is very useful to characterize pollutant dispersion and deposition and to understand source- receptor relationships. In cases where the resolved wind flow and atmospheric turbulence are significantly affected by the presence of buildings or complex terrain, standard analytical models such as Gaussian puff or plume models may not be appropriate; instead, computational fluids dynamics (CFD) models are a more appropriate method for this kind of modeling study. This paper describes the incorporation and adaptation of dry and wet deposition schemes for atmospheric particulate matter dynamics in Mercure-Saturne, a CFD model, which is coupled with a modal aerosol model, capable of following the formation and dispersion of particles. Several sensibility tests were performed to ensure that the coupling of the models was functioning correctly. Cadmium is one of the major heavy metals emitted by road traffic and it was, therefore, selected for a modeling case study near an expressway in France, where roadside measurements are available for a simple case in flat terrain. Emission estimation for cadmium is discussed in details. The CFD simulation results are compared with two Gaussian models results and with measurements at different distances from the road. Even for this simple geometry, the results demonstrate that, near the source, the CFD model has significantly better results than Gaussian models. Farther downwind from the source, the results of the CFD model and Gaussian models are more similar. Spatial patterns of road traffic-related cadmium deposition and factors influencing these patterns are discussed. For a monthly average period, cadmium deposition rates decrease from 5 m to 20 m, 40 m, 80 m, and 160 m by about 60%, 73%, 80%, and 90%, respectively. These road-related deposition rates are compared with background values to characterize the potential impact of road-traffic as a source of pollutant deposition. Perspectives of applications of this model in more realistic settings such as in urban area are discussed.

Arnaud L.,University of Lyon | Arnaud L.,National School of Public Civil Engineering | Houel A.,CETE de Lyon
IOP Conference Series: Materials Science and Engineering | Year: 2014

This paper deals with the modelling of wearing courses on steel orthotropic decks such as the Millau viaduct in France. This is of great importance when dealing with durability: due to the softness of such a support, the pavement is subjected to considerable strains that may generate top-down cracks in the layer at right angles of the orthotropic plate stiffeners and shear cracks at the interface between pavement and steel. Therefore, a five-point bending fatigue test was developed and improved since 2003 at the ENTPE laboratory, to test different asphalt concrete mixes. This study aims at modelling the mechanical behavior of the wearing course throughout the fatigue test by a finite element method (Comsol Multiphysics software). Each material-steel, sealing sheet, asphalt concrete layer-is considered and modelled. The modelling of asphalt concrete is complex since it is a heterogeneous material, a viscoelastic medium and it thermosensitive. The actual characteristics of the asphalt concrete (thermo physical parameter and viscoelastic complex modulus) are determined experimentally on cylindrical cores. Moreover, a damage law based on Miner's damage is included in the model. The modelling of the fatigue test leads to encouraging results. Finally, results from the model are compared to the experimental data obtained from the five-point bending fatigue test device. The experimental data are very consistent with the numerical simulation. © 2010 IOP Publishing Ltd.

Rey G.,University Blaise Pascal | Clair D.,University Blaise Pascal | Fogli M.,University Blaise Pascal | Bernardin F.,CETE de Lyon
Mechanical Systems and Signal Processing | Year: 2011

The work presented here aims to develop a warning device to prevent roadway departure while cornering. Given the random variability arising from the driver, the vehicle and the infrastructure at the entrance of the curve, a probabilistic strategy is adopted to assess the roadway departure risk. Random variables and processes are introduced in a specifically developed vehicle dynamics model. The driver's behaviours are deduced from real traffic measurements. Structural reliability methods are employed to compute a roadway departure risk index, used to take the decision of an alarm triggering. Particular care is brought to the reduction of the computational cost. Refinements made on the standard reliability methods to handle with the model non-linearities and the stochastic dimension are presented. © 2010 Elsevier Ltd.

Belloche S.,CETE de Lyon
19th Intelligent Transport Systems World Congress, ITS 2012 | Year: 2012

Speed control allows a road operator to adapt in real-time the speed limit to the traffic conditions encountered by road users. However, the impacts of variable speed limits depend mainly on the network characteristics and therefore the deployment of this measure is not always relevant to tackle with congestion. On the Lorrain corridor -a motorway corridor in Eastern France -, congestion often occurs on three specific sections and the most appropriate solution seemed to be the deployment of variable speed limits. However, it was not possible to quantify the impacts of this deployment and to know whether this solution was really effective or not. So, it has then been decided to assess the impacts of this solution before deploying the measure on the three sections, and, despite the fact that it has not yet been done so at least in France, the use of simulation appeared to be the best tool to do so. Consequently, this paper aims at describing the chosen methodology, the problems it has raised, the results of this ex-ante evaluation and the decision that has been taken about the deployment of variable speed limits on these sections.

This article presents a case study focusing on the strengthening of a French road bridge by externally bonded FRP composites. The bridge under study is a viaduct made of pre-stressed concrete girders located near Toutry in Burgundy (France) on the A6 highway. It reports the work conducted by the technical staff of the CETE de Lyon (Engineering Centre of the French Ministry of Sustainable Developments), who were involved in the inspection of the construction site. During this mission, loading tests were performed in order to evaluate the effectiveness of the bridge strengthening. Strain and deflection measurements were compared to a numerical modelling of the structure. It was found that deflections of several beams of the loaded bridge were strongly reduced after the installation of composite reinforcements, much beyond the estimations provided by the model. © 2012 Lavoisier.

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