Seven tunneling jumbos have been purchased by the Şenbay-Özgün Joint Venture, part of the Bayburt Group, from Sandvik for its Doğançay realignment project on the Istanbul–Ankara high-speed rail upgrade project in Turkey. A major part of the contract is excavation of a 10km tunnel and some 1.4 million m3 of rock.
Fig 1. Location of the Doğançay tunnel project
Turkish State Railway awarded the Doğançay project to the main contractor Şenbay-Özgün JV on 10 May 2013.
The new 10km long tunnel is being built in the city of Sakarya (Fig 1), with the purpose to cut down the distance between the Turkish capital Ankara and its principal city Istanbul. According to a Sandvik news release, excavation of the 1.4 million m3 of material is scheduled to take 180 days, and be completed in November 2013.
The Bayburt Group, as parent of the Şenbay-Özgün JV, purchased the seven Sandvik drill rigs for the project. Five units are Sandvik DD321-40 rigs and two are Sandvik DT820s. Excavation of the high speed railway project tunnel will be challenging due to fractured and weak rock types including siltstone, claystone and mudstone. The Bayburt Group are said to have chosen Sandvik underground drill rigs as they are trouble-free and easy to operate. Another key factor, according to Sandvik, is its high quality service and support network in Turkey.
According to Turkish State Railways, existing line between Ankara and İstanbul is a total 576km. Once the high speed line upgrade is completed, including the construction of a double track and realignments to accommodate speeds of up to 250km/hr, the rail distance between the two cities will decrease to 533km and the travel time will shorten from 7hr to 3hr (Fig 2). A major part of the new line is the immersed tube rail crossing of the Bosphorus, which is due to open this year (2013).
A DD321-40 jumbo at the face
Table 1. Technical data
8 - 49m2
12 - 110m2
43 - 64mm
43 - 64mm
2,830 - 4,660mm
up to 6,180mm
2 x SB40
2 x TB90
2 x TF500, 16ft
2 x RD520, 20kW
2 x HLX5T, 22kW
Length (with default feed)
For the most part, the new line follows the existing alignment except at the points of realignment need to either reduce gradients or widen alignment curves to meet high-speed rail requirements. The route was divided into seven project sections, the stage of which, between Esenkent, near Ankara, and Eskisehir, was completed and taken into operation in March 2009. For the Eskishehir-Köseköy section, three alternatives were considered for the Köseköy Section and of these the alternative that would be 33km shorter than the original line and included construction of the 10km long twin tube tunnel, for a total of about 23km of tunnelling, to conform to UID and EU criteria for emergency escape stations was selected as the resulting Doğançay Realignment. This realignment enables a wider radius of some 3,500m, which is suitable for high-speed rail where the current track included curves of tight 400m radii.
Fig 2. Full extent of the Ankara-Istanbul high-speed line
Bosphorus undersea rail crossing update
As construction of the upgraded route between Istanbul and Ankara progresses, the vision of a fixed rail link between London and Beijing takes closer steps to reality.
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