From prehistoric migration to science fiction teleportation, traveling has always been part of the human imagination, either as a challenge to face in reaching a destination or as an instrument applied toward the discovery of places outside of the geographical known. The act of traveling incorporates not only the physical component of movement through space and time but also other perceptual dimensions, from sensorial – such as hearing and seeing – to behavioral and psychological ones. Within the realm of daily commute in large cities, there is a rich component of visual and sonic perceptions. Different regions of a city and times of day provide unique experiences to a person on the move in the urban space. Public transport, understood as a multiplicity, is an important component in the commuter’s perception. The rail network of São Paulo’s metropolitan region presents distinctive attributes that lend themselves to an interesting study of its sound characteristics. This multiplicity of physical structures, environment, and utilization is the study object of this sound project.