Construction work on a long-awaited road tunnel below the Bosporus in Istanbul is a step closer to reality as the tunnel boring machine (TBM) is about to be delivered to the construction site in Istanbul.
The 13.6m diameter mixshield TBM was dispatched from Herrenknecht’s factory in Germany early last month and work on building the machine on site is expected to start soon to ensure tunnelling work gets underway by the end of the year.
Work on the 5.4km long tunnel will start on the Asian side of the Turkish city and create two lane carriageway in either direction with traffic carried on two decks within the bore.
The route of the Istanbul Strait Road Tube Crossing Project runs around 100m below sea level at its deepest point and water pressures of up to 12bar are expected as the TBM passes through the geology which is predominantly sand and gravel with limestone and mudstone layers. “The project is certainly one of the most challenging tunnelling operations currently being addressed in the world,” said Herrenknecht project manager Georg Schleer.
The tunnel is being built by Turkish-South Korean construction consortium YMSK, consisting of Yapı Merkezi İnşaat ve Sanayi and SK Engineering & Construction Co.