M7 metro line The M7 Kabataş-Mahmutbey metro line is under construction. On December 20, 2013, the line was commissioned to Kalyon Group for construction.[40] The groundbreaking ceremony was held on February 9, 2014. The line will be 24.5 km (15.2 mi) long with 19 stations, and is expected to go into service in 2018.