up to 18,000 tons. The tube was placed below sea level, beneath of water and of earth. It is accessed via tunnels bored from Kazlıçeşme on the European side and Ayrılıkçeşmesi on the Asian side of Istanbul and represents the world's deepest undersea immersed tube tunnel. Fire-resistant concrete developed in Norway was essential for the safety of the project. Construction started in May 2004 and the Marmaray tunnel was completed on September 23, 2008, with a formal ceremony to mark its completion on October 13. Second phase The second phase of the project involved the renewal of the old suburban railway that ran between Halkalı and Kazlıçeşme on the European side of Istanbul and between Ayrılıkçeşmesi and Gebze on the Asian side. The work was meant to be completed at the same time as the first phase ( the tunnel and underground sections), but was delayed until March, 2019. A third line was added to enable the electric multiple unit (EMU) cars and other railway carriages to move separately. Thirty-six above-ground stations along the line were rebuilt or completely refurbished. Signalling was also modernised to allow trains to travel as close as two minutes apart (although in reality far fewer trains than that actually run). The suburban-rail upgrade part of the project, known originally as CR1, was first awarded to the AMD Rail Consortium, comprising Marubeni of Japan, Dogus Insaat of Turkey and Alstom of France. However, they were unable to complete the work and it was re-tendered as contract CR3 in early 2011. The replacement contract worth €932.8 million was awarded to a joint venture between OHL and Invensys Rail. Freight In February 2010, Railway Gazette International reported that the tunnel's administrators were hiring consultants to analyse options for carrying freight traffic. The Prime Minister and other officials have suggested that the Marmaray will help to create a modern "Iron Silk Road" by allowing freight trains to travel between Europe and China. Freight trains not carrying dangerous goods will be able to use the tunnel when commuter services are not operating (between 1:00 a.m. and 5:00 a.m.). Financing The Japan International Cooperation Agency (JICA) and the European Investment Bank (EBI) provided much of the financing for the project. By April 2006, the JICA had lent 111 billion yen and the EIB 1.05 billion euro for the work. The original cost was estimated at $4.5 billion although it finally cost