It is now possible to cross the Bosphorus Strait – from Asia to Europe in just four minutes by the new Marmaray tunnel. It is the realisation of a project dreamt up by Ottoman sultans more than a century ago.
The tunnel is the world’s first connecting two continents and was inaugurated on the 90th anniversary of the Republic of Turkey.
The engineering feat spans 13 kilometres and will carry subway commuters in Istanbul, which is Europe’s biggest city with a population of 15 million people. An estimated two million cross the Bosphorus Strait daily.
Work began in 2004 on what is one of Turkish Prime Minister Recep Tayyip Erdogan pet projects designed to change the face of Turkey.Archaeological excavations delayed completion. Eventually the tunnel will serve high-speed and freight trains.
The idea for a rail tunnel below the Bosphorus dates back to 1860 while it is believed at one time one Sultan had French engineers draw up plans for a submerged tunnel which was never built and the peninsula remained intact.
Now the Marmaray tunnel, an immersed tube set in the seabed has joined the two continents.
One point four kilometres of its full length is fully immersed some 60 metres below the surface. It can carry around 1.5 million passengers per day. The total cost topped three point three billion euros and the government hopes it will develop into an important trading route.
Marmaray is set on a silty seabed and is 20 kilometres from the active North Anatolian Fault raising fears it could be at risk from a large earthquake.
But its free floating structure has been designed to withstand a quake with a magnitude of 9. Its interlocking construction means each section can be sealed off.
The Yenikapi station on the European side of Istanbul will showcase relics which were uncovered during the tunnel’s construction. Many date back as far a 8,500 years. The excavation site included a Byzantine port and 13 shipwrecks.
The finds nearly doubled the length of time it took to complete the project and prompted UNESCO to voice concerns about the threat to the peninsula, which is a World Heritage site.