Improvements in noise mitigation of a postal delivery service: a comparison among hybrid, electric and conventional vehicles

As urbanization increases, best practice of sustainable mobility is needed to improve environmental quality in city centres. Postal companies have a significant role regarding the reduction of road traffic noise and air pollution in urban areas. In order to mitigate environmental impact, Italian postmen conventional motorcycles are being replaced with silent ecological safe four-wheel vehicles, able to easily move in limited traffic zones to deliver mail at a city level. Methodologies recommended by EU regulations were applied and acoustic measurements were carried out to assess sound pressure levels due to single vehicle passages for different road and working conditions. Noise contributions of a hybrid quadricycle were measured and they were compared with the acoustic performances of a traditional two-wheel motorcycle and an electric four-wheel vehicle. As a result of frequency response analysis, noise due to electric and hybrid vehicles differs considerably from the one due to a combustion engine motorcycle.