1. Applicability of a Screening Model at motorway and roundabout sites in Ireland. Rajiv Ganguly Una Budd Brian M. Broderick Bruce D. Misstear. Department of Civil Engineering University of Dublin, Trinity College

2. Overview v Objectives v Screening Model (DMRB) v Application of DMRB at motorway and roundabout v Comparison of two versions of DMRB (1999 & 2003) v Modification of roundabout as per DMRB-2003 v Speed versus concentration characteristics. v Conclusions 3. Overall Research Objectives To predict vehicular pollution by using a variety of atmospheric dispersion models. To perform studies by applying a variety of dispersion models to different road configurations to ascertain the applicability of each model. 4. Overall Research Objectives To carry out inter-comparison of modelled data obtained by using a variety of dispersion models by performing statistical and graphical analysis. To recommend suitable atmospheric dispersion models for vehicular pollution prediction in Ireland. To compare the monitored and predicted data sets obtained by using a variety of dispersion models by performing statistical and graphical analysis. 5. Background Information. n Road traffic is one of the major sources of air pollution and technological and transport policy measures have been developed for reduction of its impacts. n Ambient air quality standards have been set to keep pollution levels in check. n Transport sector is responsible for 50% of NOx emissions and 80% of total CO emissions in Ireland. n Pollutants considered in study were CO, Benzene, NOx and PM10. NOx and particulates have severe health impacts. 6. DMRB Screening Model Developed by UK Transport Research Laboratory. Used for initial assessment of any existing or planned road programmes. Estimates vehicular emissions from light and heavy duty vehicles upto 2020. 7. DMRB Screening Model. Primary objective is to determine whether further air quality assessments required. Model was primarily designed for CO and assumes that dispersion characteristics of other pollutants equivalent to those of CO The model in its simplest forms uses a series of look up tables based on outputs from Gaussian Dispersion model. A spreadsheet version of the model is used. 8. DMRB Screening Model. Input data for DMRB model (1999) for each link. Hourly vehicle flow. Proportion of light and heavy duty vehicles. Vehicular Speed Year Distance to Receptor. Background Concentrations. 9. DMRB Screening Model. Input data for DMRB model (2003) for each link. The new version of DMRB model (version 1.02, Nov 2003) uses the AADT values as vehicles per day rather than vehicles per year. Introduces a new concept of road type parameter. 10. DMRB applied on motorway. Criteria for site selection. High traffic flows for monitoring purposes. Traffic flow should be quantifiable. Site should allow placement of monitoring equipment near road and in downwind direction of prevailing wind. No obstruction between road and monitoring unit. Continuous power supply. 11. DMRB applied on motorway. Other Practical Criteria for site selection. Proper security arrangements Permission from the site owners. Easy accessibility to the site. The average vehicle speed was assumed to be 100km/hr at the motorway site. 12. Motorway Site Monitoring Unit M4 Carriageways (Leixlip) 13. Monitoring Location - Motorway TO DUBLIN TO WEST MONITORING LOCATION HEDGE BUILDING 25m N 14. Monitoring at Motorway Site 15. DMRB results on motorway (annual averages). Measured concentrations DMRB model Prediction Actual (2) Calculated from annual mean 1999 version (2) 2003 version CO annual average (mg/m3) 0.32 0.32 0.37 0.39 benzene annual mean (g/m3) - - 0.99 0.54 NOx annual mean (g/m3) 32.29 32.29 142.05 80.13 PM10 annual mean (g/m3) 15.50 15.50 15.83 17.99 16. DMRB results on motorway. . Salient Features. No substantial difference in CO concentration by applying both the versions of the model. Large reduction in Benzene and NOx concentration by applying 2003 version of DMRB Slight increase in Particulate concentration using 2003 version of DMRB. 17. DMRB results on motorway. n Statistical equivalents of Pollutants CO 8 hr mean=10 x CO annual average PM10(90th percentile of daily mean)=1.79 x PM10 annual average. Maximum annual running mean (benzene) = 1.102 benzene annual mean - 0.004 . 18. DMRB results on motorway (statistical equivalents). Measured concentrations DMRB model Prediction Actual (2) Calculated from annual mean 1999 version(2) 2003 version CO 8 hr mean (mg/ m3) 2.56 3.20 3.69 3.90 benzene maximum running annual mean (g/m3) 0.53 - 1.09 0.59 NO2 annual mean (g/m3) 19.37 17.09 58.27 15.86 PM10 90th percentile of annual mean. (g/m3) 22.83 27.75 28.34 32.2 19. DMRB results on motorway. finding NO2 background from NOx background concentrations 1. Obtain annual mean background NO2 (background) and NOx (background) concentrations 2. Calculate the annual mean contribution due to the road, NOx (road), at the location of interest 3. Convert the NOx (road) to NO2 (road) using the equation. 20. DMRB results on motorway. NO2 (road) = ((-0.068 x Ln (NOx (total))) +0.53) x NOx (road), where NOx (total) =NOx (background) + NOx (road), and Ln is log to the base e 4. Add the NO2 (road) to the NO2 (background) to get the NO2 (total) at the location of interest. 21. Roundabout Site Monitoring Unit N6 (Galway) 22. N6/N84 Roundabout 23. Monitoring Location - Roundabout N84/Headford Rd. N6 Sandy Road N6/Headford Rd. Menlo Rd. N 25m 15m Monitoring Unit 24. Roundabout Monitoring Unit 25. DMRB application on Roundabout. Comparison of DMRB results obtained by using 1999 and 2003 versions. Modification of 5 link problem to 3 link problem is done on basis of traffic flows. The average vehicle speed assumed was 15km/hr. Road links combined are (N84 N6) and (Menlo and Sandy road) . N6 Dublin road is third link. For the combined road links average of the traffic flows is considered. 26. DMRB model results at roundabout site (annual averages). Pollutant DMRB model results Measured Concentration 1999 5 links 2003 5 links 2003 3 links Actual Calculation from annual mean CO annual average (mg/m3) 2.09 2.25 1.36 0.54 0.54 benzene annual mean (g/m3) 12.54 4.39 2.53 - - NOx annual mean (g/m3) 774.95 283.2 165.04 39.42 39.42 PM10 annual mean (g/m3) 44.91 54.68 36.49 25.50 25.50 27. DMRB results on Roundabout. . Salient Features. No substantial difference in CO concentration by applying both the versions of the model. Large reduction in Benzene and NOx concentration by applying 2003 version of DMRB Slight increase in Particulate concentration using 2003 version of DMRB. 28. DMRB results on Roundabout. . Modification of 5 arm junction to 3 arm junction. Reduction in CO concentration by 40%. (2003 version) Reduction in benzene concentration is 42%. (2003 version) Reduction in Particulate concentration by 33%.(2003 version) Reduction in NOx concentration by 79%(1999 version) and 41% (2003 version) 29. DMRB results on Roundabout. n Statistical equivalents of Pollutants As in the motorway similar statistical equivalents of pollutants were computed also for the roundabout. Trends were the same as for annual averages for all the pollutants except benzene where no monitoring data was available for the roundabout site. 30. Pollutant DMRB model results Measured Concentration 1999 5 links 2003 5 links 2003 3 links Actual Calculation from annual mean CO 8 hr mean (mg/ m3) 20.93 3.9 13.6 2.86 5.4 benzene maximum running annual mean (g/ m3) 13.79 4.83 2.78 - - NO2 annual mean (g/ m3) 193.95 39.65 31.84 19.79 13.09 PM10 90percentile daily mean (g/m3) 80.38 97.88 65.32 39.61 45.62 DMRB model results at roundabout site (statistical equivalents). 31. Study of speed versus emission characteristics for new version of DMRB model (5 links and 3 links). n Figure 1. Comparison of speed versus concentration for CO for 5 link and 3 links model. 0 0.5 1 1.5 2 2.5 0 50 100 150 speed in km/hr concinmg/m3 from 5 link from 3 link 32. Study of speed versus emission characteristics for new version of DMRB model (5 links and 3 links). n Figure 2.Comparison of speed versus concentration for benzene for 5 link and 3 links model. 0 1 2 3 4 5 0 50 100 150 speed in km/hr concinmicrogram/m3 from 5 link from 3 link 33. Study of speed versus emission characteristics for new version of DMRB model (5 links and 3 links). n Figure 3. Comparison of speed versus concentration for NOx for 5 link and 3 links model. 0 50 100 150 200 250 300 0 50 100 150 speed in km/hr concinmicrogram/m3 from 5 link from 3 link 34. Study of speed versus emission characteristics for new version of DMRB model (5 links and 3 links). n Figure 4. Comparison of speed versus concentration for PM10 for 5 link and 3 links model 0 10 20 30 40 50 60 0 50 100 150 speed in km/hr concinmicrograms/m3 from5 link from3 link 35. For both the motorway and roundabout site the DMRB model (version 2003) gives a very reduced concentration for benzene and NOx whereas no substantial difference for CO or particulates when compared with 1999 version. At the motorway site model predictions agreed reasonably well with measured values. Conclusions For the roundabout site transforming the 5 link problem to 3 link problem as per the DMRB manual results in large reduction of concentration for all the pollutants. A screening model, DMRB has been discussed and has been applied at two different road configurations.. 36. Conclusions Irrespective of the modelling approach (3 or 5 links) or model version (1999 or 2003) employed the predicted values heavily overpredict the measured concentration. With the use of 2003 version the level of overprediction has decreased considerably . Study of the speed vs. emission characteristics show that for an average vehicle speed of 30km/hr in a 3 link model with the 2003 DMRB version leads to very good agreement between modelled and measured annual average concentrations of CO and PM10 . 37. Acknowledgement. n This work has been completed under the Environment Transport Interface (ETI) project funded by the ERTDI Research Programme which is managed by the Irish EPA and forms part of the National Development Plan. 38. Thank You