Reversed limes: Palermo Ringroad. Cataloguing the urban potential of neglected liminary spaces

Since the second half of the 20th century, the theme of liminal or in-between spaces has attracted the recurring interest of many researchers in architecture. In contemporary European cities, liminal spaces have mainly emerged through the design of major infrastructures of the last century. They are usually linear in shape and are connected to or located along the urban edges of major highways. The hypothesis we propose is that recycling heavy urban infrastructures can serve as a tool for the regeneration of contemporary cities, identifying their spaces as liminal urban places. This catalogue refers to the Ringroad that surrounds the city of Palermo and recognises the potential of the empty liminal areas along the infrastructure as new public spaces. These areas — Perpignano, Giotto, and Lazio — are large, entirely public, and municipally owned. They suggest the layout of a true linear city, where the limen (door, entrance, passage) can be found through the limes (border, barrier). The proposed design solutions include the removal of asphalt — replaced by piezoelectric paving — the addition of new trees and urban furniture to create shaded areas and mitigate perceived temperatures, and the construction of small, low-density pavilions to provide the surrounding neighbourhoods with multifunctional and multi-temporal facilities.