Experimental Correlation Between the Road Roughness and the Comfort Perceived in Bus Cabins

Road safety is a crucial topic treated by several scientific domains: vehicles and safety components design, road infrastructure technology and vehiclehuman interaction analysis. When driving or riding on road, the vibration experienced by the driver and passengers inside the vehicle cabin is one of the aspects of vehicle-human interaction. The level of ridecomfort, which is strictly related to vibration levels, influences the quality of life on board and the sense of fatigue, especially during long distance travels. In the research area of vibration in vehicles, two major domains may be identified: the investigation of vibration transmission from sources to the vehicle cabin, and the study of the effects of such vibration on passengers discomfort. The first domain involves both vehicle and road technology, while the second one mainly concerns the human exposure to whole-body vibration. Within this framework, the present paper focuses on the relationship between the two domains. This study attempts to identify the correlation between the road roughness and the comfort perceived by the driver and passengers riding in buses. The correlation is analyzed by performing both experimental tests and numerical simulations. The International Roughness Index (IRI) and the Ride Number (RN) are used for quantifying the road roughness. The international standard ISO 2631-1 is applied to evaluate the comfort level on board.