Robbins Crossover TBM breaks world records twice over
At Turkey's Eşme-Salihli Railway Tunnel, a 13.77 metre (45.18 foot) diameter Robbins Crossover XRE TBM has set new records for best day, week, and month in the 13 to 14 metre (42.6 to 46 foot) diameter range, according to the company.
The machine broke all three records first in May with 25.3 metres (83 feet) in one day, 117 metres (383.8 feet) in one week, and 345.6 metres (1,134 feet) in one month, then again in June with 28.5 metres (93.5 feet), 133.2 metres (437 feet), and 455.4 metres (1,494 feet) respectively.
The Crossover TBM has outperformed previous performance rates by a machine in its size range. The closest another 13 to 14 metre (42.6 to 46 foot) machine has come to these numbers was a 13.7 metre (45 foot) diameter mixed ground TBM that achieved a 7 metre (23 foot) average per day and a best day of 12 metres (39 feet) at the Eurasia Tunnel project.
Onur Kansu, TBM Manager for project contractor Kolin Construction, attributes the machine's success to the team operating it: "The most important reason for achieving fast advance rates is that we have an experienced and qualified team. If we open it up even further, such a team allows us to anticipate the malfunctions and to go to the solution in a very short time. In addition, all necessary maintenance is carried out on time, and the appropriate consumables are selected to increase the performance."
The machine launched on its 3.05 kilometre (1.90 miles) bore at the end of March 2021 as part of the Ankara-İzmir High Speed Railway Project for the Turkish State Railways (TCDD). Thus far, the machine has encountered a mix of mainly mudstone with gneiss.
To get through the challenging conditions, the large diameter XRE has a number of unique features. The large diameter design enables both a screw conveyor and belt conveyor to remain in place, enabling swift conversion between modes, and operation in full EPB and hard rock modes.
Regarding the future of the Turkish tunneling industry, Kansu is optimistic about the effects these new records will have: "It has been seen how well the engineers and application teams in Turkey have excelled in complex geologies and the large-scale tunneling industry. At the same time, it has shown to the whole world, especially Turkey, that with the right choices, it is possible to carry out excavations of this scale and complex geology without any problems and quickly. This project will be a pioneer in the Turkish tunneling industry, showing that faster and more economical tunnels can be built."
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