We have proposed a simple model to predict environmental noise in urban areas. In the model, the sound power level per unit area is estimated from the local traffic volume and the law of the conservation of energy is applied to derive the average value of LAeq in an area. In order to examine the actual relation between environmental noise and road traffic networks and verify the proposed model, field data on environmental noise and the distance traveled by vehicles in Nagoya City were analyzed statistically. The field data were converted into the grid square data by using GIS in 12 areas of the city. It has been found that a strong relation between LAeq and the distance traveled by vehicles is observed for each area. When the exceptional larger values of noise data are excluded and the observation time of LAeq becomes sufficiently large, the coefficients of determination exceed 0.8. The strong relation between them found to be consistent with that derived from the proposed simple model.