The 45.18ft XRE TBM set world records three times over, beating its own records in May and June with a set of records over the summer, including a best day of 106ft, a best week of 584.6ft, and a best month of 2,368ft.
Launched in March 2021, the machine bored 1.9 miles on the Esme-Salihli Railway Tunnel as part of the Ankara-İzmir High-Speed Railway Project for the TCDD.
"When the strength, force and torque generated by our Crossover TBM are taken into account, we consider it to be a beast. It has performed extremely well in this tunnel," said Onur Kansu, TBM manager for project contractor Kolin Construction. He added: "We are proud we have accomplished such high performance."
The machine began its bore in altered gneiss, then passed through mélange consisting of gneiss, sandstone, claystone, mudstone, quartz, and silt. By the end of the bore the machine was excavating in mainly mudstone.
Core drillings were taken every 200m prior to boring so the crew felt confident with the geology—just one of several factors that contributed to the record rates.
"A proper geological analysis, choosing the right TBM, a professional crew and a contractor who believes that they can break records are all key," said Kansu. "Scheduled maintenance periods, an expert team, availability of sufficient spare parts, and good logistics also made it possible for us to reach our targeted advance rates."
The project is particularly important for the Turkish tunnelling industry, showing what is possible at larger TBM diameters. "We have disproved the idea that it is difficult to reach high advance rates while boring in EPB mode with large diameter TBM. Crossover TBM enable us to find quick solutions in changing ground, so we believe they will be the preference for future projects," added Kansu.
With tunnel excavation finished, work will continue on the 508km (316-mile) line that will connect Polatlı in Ankara Province to Izmir, the third most populous city in Turkey. Once complete, the Ankara-İzmir High Speed Railway will be the longest rail line in the country, conveying passengers at top speeds of 160mph in a railway journey of about 3.5 hours.
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