A true technological jewel built
CASTIGLIONE DEI PEPOLI. The opening ceremony of the Variante di Valico on the A1 highway, the stretch between Sasso Marconi and Barberino del Mugello, took place on December 23 at the presence of the Prime Minister Matteo Renzi. Ideal stage of the ceremony, the gallery Sparvo carried out on behalf of Autostrade per l’Italia by Toto Costruzioni Generali.
With a total length of about 5,000 meters on two parallel tunnels, such work marks a series of records in the stretch of the A1 near the border between Toscana and Emilia Romagna, from the rate of excavation to the size of the machinery and to innovative technology.
For this excavation, in fact, Toto Costruzioni Generali has used the largest TBM in the world, Martina, a digging machine over a hundred meters long with a diameter of the cutter head of about 16 meters. The TBM “Martina” has allowed to dig and install the segmental lining of two tunnels in less than two years.
With this machine the men of the Sparvo tunnel reached peaks of production ever recorded before in this kind of work. In only one month, they dug and covered 400 meters of tunnel, compared to 6 months are required to tunnel through the traditional method.
An operation ever attempted before: the colossal machine has been rotated of 180 ° to allow it to excavate the second tunnel
“The ability of the structure and the inventiveness of the men of Toto GTC”, they say by the Toto company, “have allowed for another operation ever attempted before. After the first tunnel, this colossal machine has been rotated of 180 ° to allow it to excavate the second tunnel. Technicians of Palmieri, a company specialized in components, and those of Toto have created large metal cradles moved by air bearings to allow to move the gigantic components of the machine, for a total of 4500 tonnes, without dismantling most of them. This operation, never before attempted and also discouraged by German manufacturers of mega TBM, allowed to turn the machine in two weeks, saving months of work”.
Also the reinforced concrete lining is a record: the segments, of exceptional thickness and weight (70 cm to 17 tons each), were produced at the construction site by Toto, in one of the largest precast manufacturing plant ever built, capable of “churn” 80 segments per day. To ensure stability and allow the life durability of this infrastructure over time, the gallery was finally armed with a special coating steel, another innovative element.
For all these innovations, the Sparvo tunnel was awarded in London as a project of the year at the prestigious International Tunnelling Awards 2013, while Toto Costruzioni Generali has won the award for best contractor of the year.
“Among the challenges met there was only the Sparvo tunnel”, says the company, “Throughout the 25 km made by Toto there are 17 huge works, 8 tunnels and 9 viaducts. These include the viaduct Aglio, 600 meters of highway supported by piles up to 80 meters high, made of seismic isolation with innovative unbalanced cast in place cantilever. Moreover the viaduct Reno, which flows through the valley which flows the river of the same name, over 1000 meters of precast segments installed by jacking. Finally, the last in chronological order, the Val di Sambro tunnel, nearly 4 km long jointing the Toscana side with that of Emilia variant”.
“The experience of the Variante di Valico allowed us to put into practice all the skills acquired by Toto in the 50 years of activity in the field of the great works,” said Alfonso Toto, president and CEO of CG Toto. “Since 2007, here we fielded the best people and the most advanced technology in the construction of major works. We were able to meet deadlines. Elaborating and realizing also, in the course of business, technical solutions safeguard ever designed and built first. I want this to thank all the men and women of Toto that made it possible to achieve unique results in quality, technique and timing. ”