The tunnel runs uphill from near the confluence of the Golden Horn with the Bosphorus and is about 573 metres (1,880 feet) long.
Foreign embassies, hotels and commercial markets in Pera were located at the top of a steep hill while the stock exchange, banks and ports in Galata were at the bottom.
The main street between these two areas, Yüksek Kaldırım (High Pavement) Avenue, saw an average of 40,000 people walking up and down it daily.
Gavand came up with the idea of building a funicular railway that would ascend and descend the hill and went back to France shortly after to prepare his project.
During the war, Gavand went to the United Kingdom and formed the Metropolitan Railway of Constantinople to develop the line.
In 1911, after some alterations, the rights to the Tünel were transferred to the new multinational consortium, Union Ottoman Société d'Intrepises Electriques à Constantinople.
[5] In 1939 it was absorbed into the new IETT (İstanbul Elektrik Tramvay ve Tünel) transport organisation.
One car was reserved for passengers, with its two classes provided divided into separate sections for men and women.