At that time, the city did not have a mass transit rail system, except for a single 0.57 km (0.35 mi) funicular line known as Tünel – the last operating original tramline was closed in 1969.

Istanbul desperately needed a rapid transit rail system to help transport its large population.

[1] On December 18, 1989, the line was extended to Esenler,[1] but at that time the Otogar (Intercity Bus Station) was omitted.

Finally, the M1A branch line was completed on December 20, 2002, when the extension to the World Trade Center and Atatürk Airport in Yeşilköy opened.

[2][3] Using the M2 and Marmaray, passenger may travel north of the Golden Horn to Taksim, Mecidiyeköy, Levent and Maslak as well as across the Bosphorus to Üsküdar and Kadıköy.

İDO seabuses offer service to coastal districts of Istanbul as well as other cities and towns on the Sea of Marmara.

The connection station at Otogar in Esenler has two island platforms, which enable traffic on three tracks by the two different M1 branch lines.

The connection station at Otogar in Esenler has two island platforms, which enable traffic on three tracks by the two different M1 branch lines.