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Atmospheric dispersion of air pollutants carbon monoxide and particulate matter around road intersections in Singapore
Author
Ye, Jing
Supervisor
Teo, Khay Chuan
Koh, Thiam Seng
Abstract
The established CAL3QHC model for air pollution modeling of carbon monoxide (CO) and particulate matter (PM) is studied to examine its applicability for use under Singapore envirom~ental settings. To date, the CAL3QHC model is the best one to predict air pollutant CO concentration and is able to predict PM concentration in the atmosphere at road intersections under North American settings. However, the model has not been applied to predict CO and PM concentrations in a metropolitan country that is near the equator such as Singapore, which has predominantly unstable tropical climatic conditions, with high humidity level, high rainfall, warm weather and variable wind directions throughout the year.
In our study, we tested the model's suitability for used in four separate road intersections in Singapore. The first location was a "T-shape" road intersection. The second location was a cross road intersection that was close to an industrial area. The third location was a complex road intersection where an expressway, several main and minor roads converged. The last location was also a complex intersection that included a circus and fly-over road.
In order to improve the predicted values, certain assumptions and modifications of input parameters for the model were made. The air pollutant concentrations at a "Tshape" intersection were calculated by using a standard cross road intersection to model the "T-shape" intersection where the input parameters for the traffic flux of the imaginary fourth road leading to this "T-shape" intersection were set to relatively low values. The mathematical axiom of superposition was a road intersection that included a fly-over road. The application of the mathematical axiom allowed roads at the intersection that were not on the same plane to be treated as if they were on one imaginary plane for the purpose of pollutant concentration calculations.
After the appropriate revisions, the Cal3QHC model was able to predict the CO concentrations as the four locations satisfactorily but the calculated PM concentrations at these locations suffered from gross error. Generally, the predicted concentrations for CO from the revised model deviated on an average of *l 5% from the monitored values.
In our study, we tested the model's suitability for used in four separate road intersections in Singapore. The first location was a "T-shape" road intersection. The second location was a cross road intersection that was close to an industrial area. The third location was a complex road intersection where an expressway, several main and minor roads converged. The last location was also a complex intersection that included a circus and fly-over road.
In order to improve the predicted values, certain assumptions and modifications of input parameters for the model were made. The air pollutant concentrations at a "Tshape" intersection were calculated by using a standard cross road intersection to model the "T-shape" intersection where the input parameters for the traffic flux of the imaginary fourth road leading to this "T-shape" intersection were set to relatively low values. The mathematical axiom of superposition was a road intersection that included a fly-over road. The application of the mathematical axiom allowed roads at the intersection that were not on the same plane to be treated as if they were on one imaginary plane for the purpose of pollutant concentration calculations.
After the appropriate revisions, the Cal3QHC model was able to predict the CO concentrations as the four locations satisfactorily but the calculated PM concentrations at these locations suffered from gross error. Generally, the predicted concentrations for CO from the revised model deviated on an average of *l 5% from the monitored values.
Date Issued
1998
Call Number
TD886.5 Ye
Date Submitted
1998