When a bridge is designed, we start from the basis that it is visible in all its parts. In actual fact, due to the position and speed of the observer, the bridge can be perceived partially and for a limited period of time. The area and time within which the bridge can be perceived are entities that can be quantified and, therefore, measured (Perceptive quantity). Italian legislation about infrastructures distinguishes between two forms of quality: internal, also referred to as technical performance and, more general, work function apply; and external, namely connected with the social-economic, environmental and landscape impact of the work. Footbridges make it possible to create closer relations between the user and the work, as walking on them implies moving at a slower pace. The aim of this paper was to understand how the perception of a footbridge can prove to be an effective knowledge base for planning, and an instrument for urban rehabilitation. This paper will also explore the ways in which existing footbridges can change the perception and the meaning of a place. It will also investigate the connection between the design of footbridges and planning tools. The results involve the study of the effects that a footbridge may have on the urban landscape, taking the relationship between the internal and external quality of the work into consideration.