Record advance for the Istanbul Metro 29 Mar 2018

During excavation of the Dudullu-Bostancı Metro Line in Istanbul, Turkey the Senbay Madencilik-Kolin-Kalyon JV has achieved an advance of 19 rings in a single shift on 3 March, equating to 26.6m of excavation in just 12-hours using a 6.56m diameter Terratec EPBM.

19 rings installed in just 12 hours

The TBM worked non-stop, alternating between 20-minute excavating and ring building cycles, to accomplish a new production record for a TBM of this size and class in Istanbul.

Two Terratec TBMs are being used on the metro line, which runs approximately north to south under the densely-populated Anatolian side of the city. The 14.2km-long line, along with its 13 new stations, is located entirely underground at an average depth of 30m.

The versatile mixed-face dome-style cutterheads of the Terratec TBMs with an opening ratio of about 35% have proven to work extremely effectively in Istanbul’s mixed geology – which includes sandstones, siltstones, limestones and shales. The TBM also has VFD electric cutterhead drives, tungsten carbide soft ground cutting tools that are interchangeable with 17’’ roller disc cutters, high torque screw conveyors and active articulation systems.

Assembly of the Terratec machines took place at the project’s central shaft site at Kayışdağıstation, in February 2017. By early March, the first machine had been launched on its 3,980m journey south-west to Içerenköy station and shortly thereafter the second machine began excavating north-east on its 4,377m drive towards Türk-işBlokları station.

The TBMs have maintained consistent advance rates as they have installed a tunnel lining consisting of reinforced concrete trapezoidal segments (5+1), with a 6.3m o.d., a 5.7m i.d. and a width of 1.4m. These are being produced by SKK JV at its factory in Ferhafpasa, which is located about 10km from the project worksite.

Terratec mixed face cutterhead

The achievement of such successful TBM production rates in such a densely-populated area of the city, with minimal room on site for segment or muck storage, is testament to the project team and on-site logistics,

“While planning the logistics and TBM supply, we had to consider the traffic in Istanbul,”said Enver Koc, Chief Tunnel Mechanical Engineer for SKK JV. “Traffic jams are inevitable in a city of 17 million people. So, with the need for on-time segment delivery and muck removal from site, 70% of our operations are performed during the night shift.”

The 19-ring shift was completed by the second Terratec machine, which is about 75% through its drive and due to reach its final destination this June. The first machine is due to complete its final drive for the project in the next two weeks.

“This is our first experience of working with Terratec,” said Koc. “Our TBM operators adapted to the machines very quickly and Terratec has been on hand to provide quick solutions whenever we need them. We would choose Terratec machines again in the future.”

The Dudullu-Bostancı Metro project is one of five new metro lines currently being built by the Istanbul Metropolitan Municipality (IMM). Five other Terratec machines are currently at work on these projects, including the Mecidiyeköy-Mahmutbey Metro Line –which is being built by the Gulermak, Kolin & Kalyon Joint Venture – and the Ümraniye-Ataşehir-GöztepeMetro Line, which is being built by the Gulermak, Nurol & Makyol JV. Due for completion in 2019, the new lines will increase the city’s current 145km Metro network to more than 480km.