Evaluation of composite noise measurement methods in land transportation systems in Taiwan

In recent years, there have been frequent public complaints about noise disturbance from land transportation systems in metropolitan areas, particularly regarding the composite noise impact from different transportation systems. To clarify the contributions of different land transportation system noise sources, this study selected three locations with different composite land transportation system noise complaints. Three methods including Class 1 sound level meters, microphone arrays, and computer model simulation were employed to investigate the noise source contribution proportions and separation. Field measurements revealed that the primary noise source was from ground-level highway sections, with contribution levels consistently exceeding 70%. Furthermore, comparison between Class 1 sound level meter measurements and Cadna A computer model simulations showed that the simulated values were within ±3dB(A) of measured values, with consistent overall trends. These findings provide a methodology for determining noise source responsibility and serve as a reference for environmental protection agencies in handling public complaints about composite transportation system noise.