Traffic noise of 650 vehicles classified into 8 vehicle classes were measured in several locations within the Western Province of Sri Lanka in order to extract the necessary coefficients to develop a road traffic noise prediction model. The model was developed to predict the traffic noise generated from free-flowing vehicles in roadways. Traffic flow data used for constructing this model was limited to vehicle noise, vehicle class, vehicle speed and the distance from the traffic flow line. It is shown that the predictions can be made within ±11 dB(A) accuracy with respect to the actual experimental observations. Microsoft.Net (R)platform was used for the development of the traffic simulator based on the model parameters.