The Tunnel is a short underground railway line in Istanbul, Turkey. It is an underground funicular with two stations, connecting the quarters of Karaköy and Beyo?lu. Located at the northern shore of the Golden Horn, the underground railway tunnel goes uphill from close to sea level and is about 573 metres long. Inaugurated on January 17, 1875, the Tünel is the second-oldest subterranean urban rail line in the World after the London Underground (1863), and the first subterranean urban rail line in continental Europe; though the first full subway line with multiple underground stations in continental Europe was Line 1 of the Budapest Metro (1896).
The Tünel was originally conceived by the French engineer Eugène-Henri Gavand in 1867. Its purpose was to provide an easy ride between the neighbourhoods of Pera (Beyo?lu) and Galata (Karaköy), both of which were in the relatively newer part of Istanbul, on the northern shore of the Golden Horn. Many people used to work in Galata close to sea level, and live uphill in Pera, about 60 metres higher. The only direct street connecting the two, Yüksek Kald?r?m, is steep and narrow; at the time of the construction of the Tunnel, it was crowded with 40,000 pedestrians a day. Gavand conceived of the Tünel as "a kind of elevator ascending and descending" that would greatly ease the journey.
Two years later, on June 10, 1869, Gavand received permission from the Ottoman sultan Abdülaziz to start the project with a forty-two year concession to operate it. After finding foreign funding, Gavand established a company called the Metropolitan Railway of Constantinople to carry out the project. Construction began on July 30, 1871 but was delayed significantly by conflicts between landowners and the company. The tunnel was not completed until December 1874 and was finally opened for service on January 17, 1875.
The Metropolitan Railway company gained a fresh 75-year concession in 1904 but the Tünel was nationalised in 1923 when the Turkish Republic was proclaimed. In 1939 it was absorbed into the new IETT (?stanbul Elektrik Tramvay ve Tünel) transportation organization. It was modernised and electrified in 1971. Today, the short line is no longer as vital for Istanbul's inner city traffic as it used to be back in the 19th century, but it is still a part of the municipal transport network and integrated tickets are valid.
The Tunnel consists of a single brick-lined tunnel measuring 554.8 metres (1,820 ft) long, 6.7 metres (22 ft) wide and 4.9 metres (16 ft) high. It has one station at either end. The lower station is named Karaköy (located on the eastern end of Tersane Avenue at 41.0229°N 28.9749°ECoordinates: 41.0229°N 28.9749°E), and the upper station Tünel Meydan? Tünel Square (located on the southern end of Istiklal Avenue at 41.0278°N 28.9719°E). The upper station stands 61.55 metres (201.9 ft) higher than the lower one. The slope of the tunnel varies along its length from 2 percent to 15 percent. It was originally built with two parallel lines, but now has a single track with a short duplex section in the middle, where two trains pass side by side.
The original rolling stock on the Tünel consisted of two wooden two-car trains. One car was reserved for passengers, with two classes provided, each of which had separate compartments for men and women. The other car was used to transport goods, animals and even horse-drawn carriages. Motive power was provided by steam engines.
The wooden carriages were replaced in 1971 with two electrified steel cars running on pneumatic tires. Their cruising speed is roughly 25 km/h. A trip between the two stations takes about 1.5 minutes, with an extra two minutes of waiting between operations to allow passengers to board the train.