Footbridge design in Viale Regione Siciliana in Palermo

The paper investigates some solutions designed by the author, as structural consulting engineer of the municipal administration of Palermo, to build a footbridge over Viale Regione Siciliana, in the section between Via Perpignano and Viale Leonardo Da Vinci. The pedestrian underpass put in place in the 1990s, during the construction of the new road, was considered to be unsatisfactory for pedestrian safety due to possible robberies. In the last few years the administration has been oriented towards the creation of footbridges, designed to be accessible to the differently abled too. This is possible in relationship to the definitive abandonment of the project of a flyover. The paper shows some designs for the footbridges from Piazza John Lennon to Piazza Einstein developed by D. Perroult and refers to other structures in line with Via Palmerino and Via Santa Maria di Ges\uf9. All the bridges have steel structures, usually with reticular configuration. With reference to the Perpignano footbridge we describe the problems connected to the localization of the footbridge for which two solutions were considered: i) near Via Perpignano, passing over the new traffic circle ii) near Via Nazario Sauro, almost halfway along the section between the two consecutive subways. Both solutions used structural steel. Specifically, the two definitive versions utilized cable-stayed systems. In the first case the cables are attached to a central tower; while in the second case, which was approved, the cables are anchored to an asymmetrical tower situated below the road. The system used is a tubular steel structure having a hexagonal transversal section, sustained by 4 couples of cables. The paper discusses some design questions of a general character and shows the executive project of the footbridge. Keywords: steel structures, cable-stayed systems, footbridges, wind load