The Kadıköy – Kartal Rail Mass Transporation System construction works introduced by the General Directorate of İstanbul Electricity, Tram and Tunnel (İETT) is contracted on 28.01.2005 with the Doğuş İnşaat ve Ticaret A.Ş. – Yapı Merkezi İnşaat ve Sanayi A.Ş. – Yüksel İnşaat A.Ş. – Yenigün İnşaat Sanayi ve Ticaret A.Ş. and Belen Limited partnership. Due to conversion of the system to an underground metro, the revised contract amount of the system has reached USD 592.432.532.