Turkey started a test run for a 13.6-km tunnel under the Bosphorous strait linking the Asian and European sides of Istanbul on Sunday.

Turkish Prime Minister Recep Tayyip Erdogan attended the ceremony for the Marmaray tunnel, which is due to open on October 29, the 90th anniversary of the founding of the Republic of Turkey.

The services will initially operate between Kazilicesme, Yenikapi and Sirkeci on the European side and Uskudar on the Asian side until the rest of the project is completed. The line will ultimately run for 76.3 km from Halkali in the west to Gebze in the east.

The construction of the tunnel began in August 2004 and $2.7 billion has been invested in the project so far. The total cost is expected to be $5 billion.

The transport capacity for both directions will be 1.2 million passengers per day.

After commissioning of the tunnel, the volume of railway transport in Istanbul will increase by about 20 percent.