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Alain Clappier - One of the best experts on this subject based on the ideXlab platform.

  • Fast and optimized methodology to generate road Traffic Emission inventories and their uncertainties
    CLEAN - Soil Air Water, 2014
    Co-Authors: Alain Clappier, Nadège Blond
    Abstract:

    Road Traffic Emissions are one of the main sources of air pollution in the cities. They are also the main sources of uncertainties in the air quality numerical models used to forecast and define abatement strategies. Until now, the available models for generating road Traffic Emission always required a big effort, money and time. This inhibits decisions to preserve air quality, especially in developing countries where road Traffic Emissions are changing very fast. In this research, we developed a new model designed to fast produce road Traffic Emission inventories. This model, called EMISENS, combines the well-known top-down and bottom-up approaches to force them to be coherent. A Monte Carlo methodology is included for computing Emission uncertainties and the uncertainty rate due to each input parameters. This paper presents the EMISENS model and a demonstration of its capabilities through an application over Strasbourg region (Alsace), France. Same input data as collected for Circul’air model (using bottom-up approach) which has been applied for many years to forecast and study air pollution by the Alsatian air quality agency, ASPA, are used to evaluate the impact of several simplifications that a user could operate . These experiments give the possibility to review older methodologies and evaluate EMISENS results when few input data are available to produce Emission inventories, as in developing countries and assumptions need to be done. We show that same average fraction of mileage driven with a cold engine can be used for all the cells of the study domain and one Emission factor could replace both cold and hot Emission factors.

  • road Traffic Emission inventory for air quality modelling and to evaluate the abatement strategies a case of ho chi minh city vietnam
    Atmospheric Environment, 2011
    Co-Authors: Alain Clappier
    Abstract:

    Abstract A road Traffic Emission Inventory (EI) is generated for Ho Chi Minh City (HCMC), Vietnam. For generating the EI for road Traffic sources, we used the new EMISENS model, which combines the top-down and bottom-up approaches. The bulk Emission factors of Traffic stem from another study that estimated the Emission factors for HCMC by using an inverse air quality model method. The results show that the motorcycles are responsible for the bulk of Traffic Emissions (contributing 94% of CO, 68% of NMVOC, 61% of SO2 and 99% of CH4). Four scenarios for reducing of the Traffic Emissions are designed using the HCMC’s plan for reduction of Emissions. Two scenarios are the reduction scenarios for the year of 2015 and 2020. In addition, two scenarios are the Business as Usual scenario for the year of 2015 and 2020. If the local government does not have any plan for reduction of Emissions (scenario of Business as Usual) the Emissions will increase rapidly. If the government follows the planning as set out by the local managers, the Emissions of the city will decrease.

  • An evaluation of the estimation of road Traffic Emission factors from tracer studies
    Atmospheric Environment, 2010
    Co-Authors: Luis Carlos Belalcazar, Alain Clappier, Nadège Blond, Thomas Flassak, J. Eichhorn
    Abstract:

    Road Traffic Emission factors (EFs) are one of the main sources of uncertainties in Emission inventories; it is necessary to develop methods to reduce these uncertainties to manage air quality more efficiently. Recently an alternative method has been proposed to estimate the EFs. In that work the Emission factors were estimated from a long term tracer study developed in Ho Chi Minh City (HCMC) Vietnam. A passive tracer was continuously emitted from a finite line source placed in one side of an urban street canyon. Simultaneously, the resulting tracer concentrations were monitored at the other side of the street. The results of this experiment were used to calculate the dispersion factors and afterwards, these dispersion factors were used to estimate the EFs. In this paper we use the Computational Fluids Dynamics (CFD) model WinMISKAM to critically evaluate the proposed methodology. In a first step, we use the results of the tracer study to validate the CFD model. Results show that the model is able to simulate quite well the tracer dispersion in most of the cases. The model is then used to evaluate the effect of varying the source configuration and to correct the EFs. A comparison with available studies shows that the corrected EFs are within the range of the EFs reported in other studies. Finally, the CFD model is used to find a source configuration that better represents the vehicle Emissions and that may be used in future studies to estimate the EFs more accurately. Results show that a 200 m line placed in the center of the street would represent very well the vehicle Emissions. This work shows that it is possible to accurately estimate the EFs from tracer studies.

  • An evaluation of the estimation of road Traffic Emission factors from tracer studies
    Atmospheric environment, 2010
    Co-Authors: Luis Carlos Belalcazar, Alain Clappier, Nadège Blond, Thomas Flassak, J. Eichhorn
    Abstract:

    Road Traffic Emission factors (EFs) are one of the main sources of uncertainties in Emission inventories; it is necessary to develop methods to reduce these uncertainties to manage air quality more efficiently

  • estimation of road Traffic Emission factors from a long term tracer study
    Atmospheric Environment, 2009
    Co-Authors: Luis Carlos Belalcazar, Minh Ho, Erika Zarate, Oliver Fuhrer, Alain Clappier
    Abstract:

    Abstract Road Traffic Emissions, one of the largest source categories in megacity inventories, are highly uncertain. It is essential to develop methodologies to reduce these uncertainties to manage air quality more effectively. In this paper, we propose a methodology to estimate road Traffic Emission factors (EFs) from a tracer experiment and from roadside pollutants measurements. We emitted continuously during about 300 non-consecutive hours a passive tracer from a finite line source placed on one site of an urban street. At the same time, we measured continuously the resulting tracer concentrations at the other side of the street with a portable on-line gas chromatograph. We used n-propane contained in commercial liquid petroleum gas (LPG) as a passive tracer. Propane offers several advantages to traditional tracers (SF6, N2O, CFCs): low price, easily available, non-reactive, negligible global warming potential, and easy to detect with commercial on-line gas chromatographs. The tracer experiment was carried out from January to March 2007 in a busy street of Ho Chi Minh City (Vietnam). Traffic volume, weather information and pollutant concentrations were also measured at the measurement site. We used the results of the tracer experiment to calculate the dilution factors and afterwards we used these dilution factors, the Traffic counts and the pollutant concentrations to estimate the EFs. The proposed method assumes that the finite Emission line represents the Emission produced by Traffic in the full area of the street and therefore there is an error associated to this assumption. We use the Computational Fluids Dynamics (CFD) model MISKAM to calculate this error and to correct the HCMC EFs. EFs for 15 volatile organic compounds (VOCs) and NO are reported here. A comparison with available studies reveals that most of the EFs estimated here are within the range of EFs reported in other studies.

Werner A Stahel - One of the best experts on this subject based on the ideXlab platform.

  • comparison of a road Traffic Emission model hbefa with Emissions derived from measurements in the gubrist road tunnel switzerland
    Atmospheric Environment, 2005
    Co-Authors: Christina A Colberg, Bruno Tona, Werner A Stahel, Markus Meier, J Staehelin
    Abstract:

    Abstract Road vehicle Emissions contribute significantly to air pollution. These Traffic Emissions are characterized by Emission factors (EFs), which describe the emitted mass of a compound per driven distance. Here, we present a comparison of EFs which were obtained with two different techniques: (i) Trace gas measurements in the Gubrist tunnel, Switzerland in fall 2002 (Colberg et al., 2005. Atmospheric Environment, in press) provided real-world EFs of entire vehicle fleets and, after statistical regression analysis, additionally the EFs of different vehicle classes. Furthermore, a 12 year time series of EFs of measurements in the Gubrist tunnel in Switzerland is being used (Steinemann und Zumsteg, 2003, Bericht US 89-16-11 fur OSTLUFT durch Amt fur Abfall, Wasser, Energie und Luft des Kantons Zurich (AWEL), Switzerland). (ii) Based on dynamometric test measurements and engine maps at different conditions, EFs of single vehicles are combined with a comprehensive road Traffic Emission model (HBEFA, 1999. Umweltbundesamt Berlin, Bundesamt fur Umwelt, Wald und Landschaft Bern (published as software on CD-ROM), Infras AG, Bern; HBEFA, 2004. Umweltbundesamt Berlin, Umweltbundesamt Wien, Bundesamt fur Umwelt, Wald und Landschaft Bern (published as software on CD-ROM), Infras AG, Bern). The results of both techniques are processed and if enough information on the vehicle fleet is available, a comparable standard is achieved, which allows the validation of the road Traffic Emission model. Since two HBEFA versions are being used the improvement of the model can be shown nicely. The results demonstrate good agreement for the trends of the time series measurements. However, a deviation for the absolute EFs of NO x is observed for light- and heavy-duty vehicles (LDV and HDV, respectively). The HBEFA, 2004 derived estimates are larger than 50% for LDV and 15% for HDV compared to the EF derived from the tunnel study. The deviation is even more prominent for the CO Emissions (75% overestimation for LDV and 130% overestimation for HDV). The VOC Emissions could only be compared for LDV. There the deviation is within the confidence interval of the measurements. The strengths and weaknesses of both techniques are revealed by this study.

  • comparison of Emission factors for road Traffic from a tunnel study gubrist tunnel switzerland and from Emission modeling
    Atmospheric Environment, 1999
    Co-Authors: Christian John, J Staehelin, Rainer Friedrich, Kurt Schlapfer, Werner A Stahel
    Abstract:

    Abstract The Emission factors of NOx, VOC and CO of a road tunnel study performed in September 1993 in the Gubrist tunnel, close to Zurich (Switzerland) are compared with results of Emission calculations based on recent results of dynamometric test measurements. The Emission calculations are carried out with a Traffic Emission model taking into account the detailed composition of the vehicle fleet in the tunnel, the average speed and the gradient of the road and the special aerodynamics in a tunnel. With the exception of NOx Emission factors for heavy duty vehicles no evidence for a discrepancy between the results of the tunnel study and the Emission modeling was found. The measured Emission factors of individual hydrocarbons of light duty vehicles were in good agreement with the expectations for most components.

Luis Carlos Belalcazar - One of the best experts on this subject based on the ideXlab platform.

  • An evaluation of the estimation of road Traffic Emission factors from tracer studies
    Atmospheric Environment, 2010
    Co-Authors: Luis Carlos Belalcazar, Alain Clappier, Nadège Blond, Thomas Flassak, J. Eichhorn
    Abstract:

    Road Traffic Emission factors (EFs) are one of the main sources of uncertainties in Emission inventories; it is necessary to develop methods to reduce these uncertainties to manage air quality more efficiently. Recently an alternative method has been proposed to estimate the EFs. In that work the Emission factors were estimated from a long term tracer study developed in Ho Chi Minh City (HCMC) Vietnam. A passive tracer was continuously emitted from a finite line source placed in one side of an urban street canyon. Simultaneously, the resulting tracer concentrations were monitored at the other side of the street. The results of this experiment were used to calculate the dispersion factors and afterwards, these dispersion factors were used to estimate the EFs. In this paper we use the Computational Fluids Dynamics (CFD) model WinMISKAM to critically evaluate the proposed methodology. In a first step, we use the results of the tracer study to validate the CFD model. Results show that the model is able to simulate quite well the tracer dispersion in most of the cases. The model is then used to evaluate the effect of varying the source configuration and to correct the EFs. A comparison with available studies shows that the corrected EFs are within the range of the EFs reported in other studies. Finally, the CFD model is used to find a source configuration that better represents the vehicle Emissions and that may be used in future studies to estimate the EFs more accurately. Results show that a 200 m line placed in the center of the street would represent very well the vehicle Emissions. This work shows that it is possible to accurately estimate the EFs from tracer studies.

  • An evaluation of the estimation of road Traffic Emission factors from tracer studies
    Atmospheric environment, 2010
    Co-Authors: Luis Carlos Belalcazar, Alain Clappier, Nadège Blond, Thomas Flassak, J. Eichhorn
    Abstract:

    Road Traffic Emission factors (EFs) are one of the main sources of uncertainties in Emission inventories; it is necessary to develop methods to reduce these uncertainties to manage air quality more efficiently

  • estimation of road Traffic Emission factors from a long term tracer study
    Atmospheric Environment, 2009
    Co-Authors: Luis Carlos Belalcazar, Minh Ho, Erika Zarate, Oliver Fuhrer, Alain Clappier
    Abstract:

    Abstract Road Traffic Emissions, one of the largest source categories in megacity inventories, are highly uncertain. It is essential to develop methodologies to reduce these uncertainties to manage air quality more effectively. In this paper, we propose a methodology to estimate road Traffic Emission factors (EFs) from a tracer experiment and from roadside pollutants measurements. We emitted continuously during about 300 non-consecutive hours a passive tracer from a finite line source placed on one site of an urban street. At the same time, we measured continuously the resulting tracer concentrations at the other side of the street with a portable on-line gas chromatograph. We used n-propane contained in commercial liquid petroleum gas (LPG) as a passive tracer. Propane offers several advantages to traditional tracers (SF6, N2O, CFCs): low price, easily available, non-reactive, negligible global warming potential, and easy to detect with commercial on-line gas chromatographs. The tracer experiment was carried out from January to March 2007 in a busy street of Ho Chi Minh City (Vietnam). Traffic volume, weather information and pollutant concentrations were also measured at the measurement site. We used the results of the tracer experiment to calculate the dilution factors and afterwards we used these dilution factors, the Traffic counts and the pollutant concentrations to estimate the EFs. The proposed method assumes that the finite Emission line represents the Emission produced by Traffic in the full area of the street and therefore there is an error associated to this assumption. We use the Computational Fluids Dynamics (CFD) model MISKAM to calculate this error and to correct the HCMC EFs. EFs for 15 volatile organic compounds (VOCs) and NO are reported here. A comparison with available studies reveals that most of the EFs estimated here are within the range of EFs reported in other studies.

  • Estimation of road Traffic Emission factors from a long term tracer study
    Atmospheric Environment, 2009
    Co-Authors: Luis Carlos Belalcazar, Erika Zarate, Oliver Fuhrer, Alain Clappier
    Abstract:

    Road Traffic Emissions, one of the largest source categories in megacity inventories, are highly uncertain. It is essential to develop methodologies to reduce these uncertainties to manage air quality more effectively. In this paper, we propose a methodology to estimate road Traffic Emission factors (EFs) from a tracer experiment and from roadside pollutants measurements. We emitted continuously during about 300 non-consecutive hours a passive tracer from a finite line source placed on one site of an urban street. At the same time, we measured continuously the resulting tracer concentrations at the other side of the street with a portable on-line gas chromatograph. We used n-propane contained in commercial liquid petroleum gas (LPG) as a passive tracer. Propane offers several advantages to traditional tracers (SF6, N2O CFCs): low price, easily available, non-reactive, negligible global warming potential, and easy to detect with commercial on-line gas chromatographs.

J Staehelin - One of the best experts on this subject based on the ideXlab platform.

  • comparison of a road Traffic Emission model hbefa with Emissions derived from measurements in the gubrist road tunnel switzerland
    Atmospheric Environment, 2005
    Co-Authors: Christina A Colberg, Bruno Tona, Werner A Stahel, Markus Meier, J Staehelin
    Abstract:

    Abstract Road vehicle Emissions contribute significantly to air pollution. These Traffic Emissions are characterized by Emission factors (EFs), which describe the emitted mass of a compound per driven distance. Here, we present a comparison of EFs which were obtained with two different techniques: (i) Trace gas measurements in the Gubrist tunnel, Switzerland in fall 2002 (Colberg et al., 2005. Atmospheric Environment, in press) provided real-world EFs of entire vehicle fleets and, after statistical regression analysis, additionally the EFs of different vehicle classes. Furthermore, a 12 year time series of EFs of measurements in the Gubrist tunnel in Switzerland is being used (Steinemann und Zumsteg, 2003, Bericht US 89-16-11 fur OSTLUFT durch Amt fur Abfall, Wasser, Energie und Luft des Kantons Zurich (AWEL), Switzerland). (ii) Based on dynamometric test measurements and engine maps at different conditions, EFs of single vehicles are combined with a comprehensive road Traffic Emission model (HBEFA, 1999. Umweltbundesamt Berlin, Bundesamt fur Umwelt, Wald und Landschaft Bern (published as software on CD-ROM), Infras AG, Bern; HBEFA, 2004. Umweltbundesamt Berlin, Umweltbundesamt Wien, Bundesamt fur Umwelt, Wald und Landschaft Bern (published as software on CD-ROM), Infras AG, Bern). The results of both techniques are processed and if enough information on the vehicle fleet is available, a comparable standard is achieved, which allows the validation of the road Traffic Emission model. Since two HBEFA versions are being used the improvement of the model can be shown nicely. The results demonstrate good agreement for the trends of the time series measurements. However, a deviation for the absolute EFs of NO x is observed for light- and heavy-duty vehicles (LDV and HDV, respectively). The HBEFA, 2004 derived estimates are larger than 50% for LDV and 15% for HDV compared to the EF derived from the tunnel study. The deviation is even more prominent for the CO Emissions (75% overestimation for LDV and 130% overestimation for HDV). The VOC Emissions could only be compared for LDV. There the deviation is within the confidence interval of the measurements. The strengths and weaknesses of both techniques are revealed by this study.

  • comparison of Emission factors for road Traffic from a tunnel study gubrist tunnel switzerland and from Emission modeling
    Atmospheric Environment, 1999
    Co-Authors: Christian John, J Staehelin, Rainer Friedrich, Kurt Schlapfer, Werner A Stahel
    Abstract:

    Abstract The Emission factors of NOx, VOC and CO of a road tunnel study performed in September 1993 in the Gubrist tunnel, close to Zurich (Switzerland) are compared with results of Emission calculations based on recent results of dynamometric test measurements. The Emission calculations are carried out with a Traffic Emission model taking into account the detailed composition of the vehicle fleet in the tunnel, the average speed and the gradient of the road and the special aerodynamics in a tunnel. With the exception of NOx Emission factors for heavy duty vehicles no evidence for a discrepancy between the results of the tunnel study and the Emission modeling was found. The measured Emission factors of individual hydrocarbons of light duty vehicles were in good agreement with the expectations for most components.

J. Eichhorn - One of the best experts on this subject based on the ideXlab platform.

  • An evaluation of the estimation of road Traffic Emission factors from tracer studies
    Atmospheric Environment, 2010
    Co-Authors: Luis Carlos Belalcazar, Alain Clappier, Nadège Blond, Thomas Flassak, J. Eichhorn
    Abstract:

    Road Traffic Emission factors (EFs) are one of the main sources of uncertainties in Emission inventories; it is necessary to develop methods to reduce these uncertainties to manage air quality more efficiently. Recently an alternative method has been proposed to estimate the EFs. In that work the Emission factors were estimated from a long term tracer study developed in Ho Chi Minh City (HCMC) Vietnam. A passive tracer was continuously emitted from a finite line source placed in one side of an urban street canyon. Simultaneously, the resulting tracer concentrations were monitored at the other side of the street. The results of this experiment were used to calculate the dispersion factors and afterwards, these dispersion factors were used to estimate the EFs. In this paper we use the Computational Fluids Dynamics (CFD) model WinMISKAM to critically evaluate the proposed methodology. In a first step, we use the results of the tracer study to validate the CFD model. Results show that the model is able to simulate quite well the tracer dispersion in most of the cases. The model is then used to evaluate the effect of varying the source configuration and to correct the EFs. A comparison with available studies shows that the corrected EFs are within the range of the EFs reported in other studies. Finally, the CFD model is used to find a source configuration that better represents the vehicle Emissions and that may be used in future studies to estimate the EFs more accurately. Results show that a 200 m line placed in the center of the street would represent very well the vehicle Emissions. This work shows that it is possible to accurately estimate the EFs from tracer studies.

  • An evaluation of the estimation of road Traffic Emission factors from tracer studies
    Atmospheric environment, 2010
    Co-Authors: Luis Carlos Belalcazar, Alain Clappier, Nadège Blond, Thomas Flassak, J. Eichhorn
    Abstract:

    Road Traffic Emission factors (EFs) are one of the main sources of uncertainties in Emission inventories; it is necessary to develop methods to reduce these uncertainties to manage air quality more efficiently