There are two basic ways to determine the height of a bridge: the absolute height of the structure, meaning the distance between the lowest point and the highest point; or the maximum height measured by the distance covered by a falling object, or rather the distance to the lowest point on the ground below the bridge. In many cases, the difference between these two values is minimal, while at other times the gap is considerable.
The Millau Viaduct in France, for example, is known as the tallest viaduct in the world. This bridge, which crosses the Tarn Valley near Millau, boasts an absolute height of 341 metres.
The viaduct, however, loses its primacy when considering the maximum height of fall: in this case, first place goes to China’s Beipanjiang viaduct that connects the provinces of Yunnan and Guizhou, soaring over the Beipan River. Inaugurated in 2016, the bridge is 565 metres from the river deep down in the canyon. With its 1,341 metres in length, this viaduct was built in three years at a cost of around €130 million.
Even in Italy, however, we can boast very high bridges. Which is the tallest viaduct in the country?
Before discovering the tallest viaduct in Italy, it is perhaps appropriate to underline what is the difference between a bridge and a viaduct. If all viaducts are bridges, it cannot be said that all bridges are viaducts.
The viaduct is a particular type of bridge: it is a work of engineering composed of a succession of spans that cross wide valleys or, in urbanised environments, other underlying structures, such as busy roads, metro lines and so on.
So the term “bridge” should be used specifically to describe a structure that stands almost exclusively over a river, a lake or a stretch of a larger body of water. The term “viaduct” indicates instead a structure that crosses a place where water is absent, or constitutes only a small part of the width of the structure. In this sense, an overpass is a particular and restricted example of a viaduct, used to easily overcome a road situated below it.
In the “Bel Paese” there is certainly no lack of tall bridges, capable of causing vertigo with their very tall pillars. Looking at the total height of the pylons, or the absolute height of the structure, the tallest viaduct in Italy is the Sente Viaduct at 185 metres. This bridge, which rises on the border between Molise and Abruzzo, was built in steel and concrete between 1974 and 1977. It crosses the narrow valley formed by the river of the same name. It is one of the most impressive structural works in the country, with spans of 200 metres. It should be emphasised that, as of May 2, 2011, the official name of the tallest viaduct in Italy is "Sente Longo", in honour of a worker - Francesco Paolo Longo - who lost his life during the excavation work for the bridge.
Currently the Sente Longo viaduct is closed to traffic: a decision taken following in-depth checks carried out immediately after the dramatic events in Genoa. It was found that a pylon (Number 3) rotated on its axis, decreasing the support base with which it keeps the viaduct up. So there is a wait for work to secure the third pile (to be carried out presumably by drawing on funds made available with the Genoa Decree). The start date has not yet been decided.
According to the same measurement standard, the second tallest viaduct in Italy is the Cadore Bridge, which measures only one metre less in height than the Sente Longo. The viaduct that soars over the gorge of the Piave River, between Pieve di Cadore and Perarolo di Cadore, is 184 metres high and a little over a kilometre long. This work was fundamental to improve the viability of the area between Cadore and Cortina d'Ampezzo.
Looking instead at the height of the nave, and therefore the maximum distance covered by a falling object, the tallest viaduct in Italy is the Italy Viaduct, located along the Salerno-Reggio Calabria motorway that crosses the valley of the river Lao. The central span rises 259 metres from the bottom of the valley: this height made the Viadotto Italia the tallest bridge in Europe until 2004, the year in which the aforementioned viaduct of Millau in France was completed. However, it remains the second tallest viaduct in Europe.
The Italy Viaduct was built between 1966 and 1969, based on a preliminary project by Fabrizio de Miranda, Carlo Cestelli Guidi and Carmelo Pellegrino Gallo, and on a subsequent one by Enzo Bedeschi and Lucio Casciati, of the Lodigiani company (which would later become part of Salini Impregilo).
Still keeping in mind the maximum distance of a falling object, the second tallest viaduct in Italy - and the third at European level - is the Sfalassà Viaduct. Also known as Ponte di Bagnara, this viaduct is part of the Mediterranean motorway, and boasts a height of 253 metres. Designed by Silvano Zorzi, Luciano Lonardo and Sabatino Procaccia and inaugurated in 1972, it is the highest span frame bridge in the world.