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Martina’s roto-translation

The 180-degree roto-translation of the approximately 4500 tons of the TBM Martina, an operation never attempted before and even considered impossible by its manufacturers, was carried out in record time using a brilliant expedient: inspired by the “Hovercraft”, the engineers of the Toto Costruzioni Generali Group and the Palmieri company, created the AIRMOVER 3000. No crane in the world would have been able to move a mass like Martina’s in a single solution and in such a short time. Thanks to AIRMOVER it was possible. The platform was made of reinforced concrete flooring of approximately 2400 square metres of laser levelled surface, then coated with thick metal lamination, which allowed the giant Martina milling cutter to be moved in blocks. The Airmover 3000 is in fact composed of 10 metal modules, each equipped with 8 compressed air cushions, which can be assembled in two different “cradle” configurations: one to move the shield, which alone weighs 3000 tons; the other for the remaining components of the TBM, 130 meters long.  The maximum pressure of each cushion is 4.2 bar, which corresponds to a lifting capacity of 43.5 tons per module. Compressed air cushions create an air layer capable of overcoming the friction exerted by the metal cradles on the platform. The system of 80 compressed air cushions at the base of the special cradle allowed the gigantic components of the TBM to slide over a thin layer of air. Once the roto-translation was completed, Martina was assembled again to proceed with the excavation of the second barrel of the Sparvo Tunnel towards Florence. The entire operation took just 15 days, a record time.

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