The work and the technique: Trans-Iranian Railway, Iran

In 1925, when the project was approved, no single construction company could build the entire railway route alone; this is why the work was divided into lots, five of which were awarded to Impresit, which then began part of the Group known today as Webuild. These were the most complex lots to carry out.

In 1927, works began. These had to consider the peculiar orography of Iran, with the need to cross geographical passes located at over 2,000 metres ASL, while also excavating 190 tunnels. 

Poor rock quality in the terrain prone to earth tremors, the climate, the great distances from the population and supply centres, and the technological limits available in the 1930s made carrying out this work a titanic effort for some 600-900 Italians, and the 12,000 local workers involved.

In the southern lot, characterized by the rugged mountains of the Khūzestān Province, more than 1,000 kilometres from the capital, the work was carried out only during the night hours of the summer season, because of the high daytime temperatures - between 40° and 50°C - that were not tolerated, even by local workers.

The northern lots foresaw building the works needed to overcome 1,000 metres of difference in level in less than 50 km of route, with serpentines and other solutions to allow the railway to function with an average slope of 2.6%. Works of this lot featured the presence of snow, which for 5 months every year covered the entire Talar valley, reaching 2 metres in height.

Works were carried out in 26 months: from the end of 1933 to 1936. In 1939, the entire railway route was completed, contributing to Iran's modernisation process.