The project concerns the works planned at the boundary between two towns, namely San Gimignano and Barberino Val D’Elsa, and between the provinces of Siena and Florence, where it is formed by the River Elsa. The new link road between the former SRT 429 regional road and the corresponding new thoroughfare fits into the more extensive plan for the “S.R.T. 429 bypass for the urban areas of Poggibonsi and Certaldo”.
The Zambra Link Project stems from the need to complete the link connecting the old SRT 429 regional road and the new one and is intended to provide a permanent solution to the issues surrounding access to the Zambra industrial area from both road axes. Starting with the intersection between the new SRT 429 regional road and the access roads around the Cusona industrial area (issues solved by the introduction of a roundabout intersection), the project involves the adaptation of a stretch of the existing roadway that runs through to the Cusona industrial area car park, where the new Zambra roundabout will regulate flows on the existing roads and on the new connection to the old SRT 429 regional road.
At the end of the parking area, work has begun on a new cable-stayed bridge, with a road underpass to be added, in line with the existing roads in the industrial area.
The bridge crosses the River Elsa and the volumetric compensation area of the parcel known as the “Molina della Zambra”. The plan involves the creation of a stretch of elevated roadway with a reinforced earth structure in order to limit the size of the new road structure, which – in this stretch – is considerably higher than the ground level. Next, the new roadway will run over the Empoli Poggibonsi railway with a single-span overpass and then run down to the new 429 roundabout, which connects with the former SRT 429 regional road.
The design activity also involved improvement of the environmental impact of the road and the design of lighting systems, safety barriers, and signposts for the link.