Making good progress on Istanbul Metro 01 Jun 2017

Two Terratec 6.56m diameter EPBMs are making good progress on the latest expansion of the Istanbul Metro system, with both machines now fully up and running and achieving good advance rates for the project.

Fig 1. Latest expansion of Istanbul Metro system

The new TBMs are being used by the Şenbay Madencilik-Kolin-Kalyon JV, along with two other machines, on the €1.4 billion Dudullu-Bostancı Metro Line project, which runs approximately north to south under the densely-populated Anatolian side of the city (Fig 1). The 14.2km-long line, along with its 13 new stations, will be located entirely underground at an average depth of 30m.

Assembly of the Terratec machines began at a central shaft site at Kayışdağı Station in early February 2017 and by early March the first machine had already been launched south-west toward Içerenköy Station. Three weeks later, the second machine also began mining north-east on its journey towards Türk-iş Blokları Station.

“We were impressed with the speed and efficiency of the TBM assembly. From clearing customs to being ready to bore so quickly was a great achievement”, said Enver Koc, Chief Tunnel Mechanical Engineer for the Şenbay Madencilik-Kolin-Kalyon JV.

The first machine excavated 4,585m towards the coast passing through stations on its way and terminating at an intermediate shaft located to the north of Ayşekadın Station. The balance of the running tunnel to Bostancı will be completed using NATM work. By the second week of May, the conveyor system for the TBM had been fully installed and it had advanced 524m.

Meanwhile, the second machine is due to complete a total distance of 5,135m to Yukarı Dudullu with another section of NATM works completing the line to Depo. Having been launched a few weeks later than the first machine, this TBM had advanced 202m by mid-May and, with all its systems fully installed, was rapidly picking up speed.

The customized Terratec TBMs have versatile mixed-face cutterheads with an opening ratio of about 35%, designed to manage the geology of Istanbul which includes low-strength sandstones, siltstones, limestones and shales. The machines also have VFD electric cutterhead drives, soft ground cutting tools that are interchangeable with 17in disc cutters, high torque screw conveyors, and active articulation systems.

The tunnel linings will consist of reinforced concrete trapezoidal segments (5+1), with an outer diameter of 6.3m, an inner diameter of 5.7m and a width of 1.4m. These are currently being produced by SKK JV at its factory in Ferhafpasa, which is located about 10km from the central project worksite.

The fully automated Dudullu-Bostancı Metro Line with driverless trains and platform screen doors at stations will provide numerous connections to other Istanbul transportation systems including the Bosphorus ferry at Bostancı Harbour, the Marmaray railway under the Bosphorus, the Kadıköy-Kartal metro line and the Üsküdar-Çekmeköy metro line.

Tunnelling is expected to be complete by spring 2018, with the project due to open to the public in mid-2019.