CeNEM-2007

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CeNEM-2007

  1. 1. Application of the General Finite Line Source Model to the prediction of Benzene concentrations adjacent to a motorway in Ireland. Rajiv Ganguly Brian M. Broderick Department of Civil, Structural and Environmental Engineering Trinity College Dublin
  2. 2. Overview v  Objectives v  General Finite Line Source Model (GFLSM) v  Comparison of Monitored and GFLSM data (M50) v  Comparison of GFLSM with CALINE4 (M50) v  Conclusions
  3. 3. Overall Research Objectives Ø  To identify suitable modelling techniques for motorway and urban street canyon. Ø  To develop models suitable for implementation in integrated transport environmental modelling.
  4. 4. Overall Research Objectives Ø  To investigate the sensitivity of model outputs to meteorological, traffic and background concentration inputs. Ø  To recommend best practice for air quality modelling of traffic emissions in Ireland. Ø  To determine the accuracy of the models through comparison of predicted and ambient air quality data .
  5. 5. Expression for GFLSM (Luhar and Patil) ( ) ( ) ( ) ( ) ( ) ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ ++ + ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ −− ⎥ ⎥ ⎦ ⎤ ⎢ ⎢ ⎣ ⎡ ⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ + −+⎟ ⎟ ⎠ ⎞ ⎜ ⎜ ⎝ ⎛ − − + = yy zzz xyp erf xyp erfx HzHz uu Q C σ θθ σ θθ σσθσπ 2 cossin 2 cossin , 2 exp 2 exp sin22 2 2 2 2 0 1
  6. 6. Schematic representation of GFLSM L x y R θ Road.
  7. 7. Study on M50 motorway. Schematic Diagram of Sampling Location. Receptors Receptors Secondary road -240m -120m -25m 25m 120m 240m NM50 Motorway Inner suburbs and city centre
  8. 8. Input Data l  Traffic volume l  Meteorological Conditions (wind speed, wind direction) l  Emission factors l  Briggs Horizontal and Vertical dispersion coefficients. Output Data. § Traffic source related concentration estimates for hydrocarbons were obtained at the receptor locations. § Results for benzene are shown below as they are more relevant for traffic emissions.
  9. 9. Results on M50 Motorway for Benzene. Variation of monitored and predicted data at 25m 0 0.1 0.2 0.3 0.4 0 5 10 15 20 sampling days concentration(ppb) monitored data CALINE4 GFLSM
  10. 10. Results on M50 Motorway for Benzene. variation of monitored and predicted data at 120m 0 0.1 0.2 0.3 0.4 0 5 10 15 20 sampling days concentration(ppb) monitored data CALINE4 GFLSM
  11. 11. Results on M50 Motorway for Benzene. variation of monitored and predicted data at 240m 0 0.03 0.06 0.09 0.12 0.15 0 5 10 15 20 sampling days concentration(ppb) monitored data CALINE4 GFLSM
  12. 12. Results on M50 Motorway for Benzene. variation of mean concentration with receptor distance (benzene) 0 0.05 0.1 0.15 0.2 0 50 100 150 200 250 distance from road(m) meanconcentration (ppb) monitored data CALINE4 GFLSM
  13. 13. Results on M50 motorway for Benzene. scatter plots for measured and predicted data at 25m 0 0.1 0.2 0.3 0.4 0.5 0 0.1 0.2 0.3 0.4 0.5 measured data (ppb) predicteddata(ppb) CALINE4 GFLSM M=P M=2P M=0.5P
  14. 14. Results on M50 motorway for Benzene. scatter plots of measured and predicted data at 120m 0 0.02 0.04 0.06 0.08 0.1 0 0.02 0.04 0.06 0.08 0.1 measured data (ppb) predicteddata(ppb) CALINE4 GFLSM M=P M=2P M=0.5P
  15. 15. Results on M50 motorway for Benzene. scatter plots of predicted data at 25m 0 0.1 0.2 0.3 0.4 0.5 0 0.1 0.2 0.3 0.4 0.5 CALINE4 GFLSM
  16. 16. Results on M50 motorway for Benzene. scatter plots of predicted data at 120m 0 0.02 0.04 0.06 0.08 0.1 0 0.02 0.04 0.06 0.08 0.1 CALINE4 GFLSM
  17. 17. Results on M50 motorway for Benzene. § Statistical Analysis of Monitored and Predicted data (a) At 25 meters. Monitored CALINE GFLSM Mean 0.15 0.19 0.19 IA 1.00 0.43 0.57 R 1.00 0.11 0.31 F2 100% 65% 95% FB 0.00 0.3 0.3 NMSE 0.00 0.43 0.44
  18. 18. Results on M50 motorway for Benzene. variation of IAwith receptor distance 0 0.2 0.4 0.6 0.8 1 0 100 200 300 receptor distance(m) IAvalues Monitored data CALINE4 GFLSM
  19. 19. Results on M50 motorway for Benzene. variation of F2 with receptor distance 0 20 40 60 80 100 0 100 200 300 receptor distance(m) F2values Monitored data CALINE4 GFLSM
  20. 20. Results on M50 motorway for Benzene. variation of NMSE with receptor distance 0 0.5 1 1.5 2 2.5 0 100 200 300 receptor distance(m) NMSEvalues Monitored data CALINE4 GFLSM
  21. 21. Ø For the M50 motorway site the performance of GFLSM has been found to be quite satisfactory when compared with CALINE4, an USEPA reference model Conclusions Ø  Further studies have been conducted for in depth evaluation of GFLSM model and it has been found that it can be readily incorporated within integrated environment transport modelling. Ø An analytical model, GFLSM has been discussed and has been applied at motorway conditions.
  22. 22. Acknowledgement. l  This work is a part of the Environment Transport Interface (ETI) project funded by the ERTDI Research Programme.
  23. 23. Thank You

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