The opening ceremony, which was held to coincide with the 90th anniversary of the founding of the Turkish Republic, was attended by Turkish President Mr Abdullah Gül and Prime Minister Mr Recep Tayyip Erdogan, Japanese Prime Minister Mr Shinzo Abe, Romanian Prime Minister Mr Victor Ponta, and Somali President Hasan Sheikh Mahmud.

The 13.3km tunnel between Üsküdar on the Asian side and Sirkeci on the European side includes a 1.4km section of immersed tube tunnel constructed at depths of up to 60m below sea level, making it the deepest tunnel of its type in the world.

Shuttle services will initially operate between Kazilicesme and Üsküdar until the rest of the project is completed. The line will ultimately run for 76.3km from Halkali in the west to Gebze in the east, reducing the journey time from 1h 45min (by train and ferry) to 1h 4min. The Marmaray line is expected to carry 1.5 million passengers per day by 2015.

The new railway is one of the first in the world to combine ERTMS and CBTC. On the surface, train detection is by jointless track circuits, and the two commuter tracks are fitted with both CBTC and ERTMS, while the third track will only have ERTMS. The tunnel will have both types of train control but train detection will be by axle counters. Fall-back lineside signalling will be installed throughout the Marmaray line.

Hyundai-Rotem is delivering a fleet of 34 10-car and 20 five-car emus for the line under a €580m contract signed in November 2008. Some of these trains are being assembled in Turkey by Eurotem a joint venture of Hyundai-Rotem and Turkish partner Tüvasaş.

The link was first proposed as long ago as 1860 by the Ottoman sultan Abdoul Medjid, but it was not until 2004 that the project was approved by Erdogan, then mayor of Istanbul.

A full description of the project can be viewed here.