Crossing(s) over the Bosporus Strait

Located on the Bosporus Strait and the Black Sea as well as in close proximity to Eastern Europe, the Caucasus and the Near East, Türkiye is of exceptional geostrategic significance. This was recognized early by the merchants of the Far East, who have been transporting their goods over the Silk Road since ancient times. Countless stories are told of this oldest trade route in the world, which included a route passing through Constantinople, now known as Istanbul, on its way to Europe. Istanbul itself is the fifteenth-largest city in the world with its population of 15.9 million, a cultural and economic metropolis that can be considered the “true center” of the country.

Trans-Caspian branch of the Silk Road

In accordance with tradition, the “New Silk Road” is still used as a trade route between Asia and Europe. The most important connection currently runs from China through Kazakhstan and Russia to Europe, but the transported volumes recently declined in the wake of the COVID19-pandemic and the Russian attack on Ukraine.
Long underestimated, but still significant, is the trans-Caspian route, which crosses Central Asia and the Caspian Sea, from Azerbaijan through Georgia and into Türkiye. One critical component in the success of this route lies in the expansion of Eurasian railway capacity. The first steps to promote rail transport along this path are already bearing fruit. Traffic here has significantly grown in the last decade: in 2014, only about 300 trains traveled this route, while in 2019 it was nearly 7,000 and after the recent geopolitical challenges the numbers reached even higher levels. At times the capacities reached their limits, which resulted in delays and longer transit times. Nonetheless plans for further expansion are still relevant as the route via the “middle branch” of the Silk Road remain a very promising trade connection for Türkiye.

Middle Silk Road as alternative

Despite the turbulent history of the region, Türkiye still sees itself as an important bridge between Asia and Europe, a potential recognized not only by merchants of the ancient world. The current government is also well aware of this economic significance and the associated demands on the country’s infrastructure. As a result, urgently needed modernization work and a staged expansion of the Turkish railway network are being driven forward at a rapid pace. One beneficial side effect: this is reducing Türkiye’s dependence on Russia and Iran with regard to transport routes, positioning the country as a new regional logistics hub.

Therefore, the previously mentioned route section from Baku (Azerbaijan) – Tiflis (Georgia) – Kars (Türkiye) is considered of great importance and investments are urgently needed: for example, the regional railway network must be expanded and electrified and modern control and safety equipment must be installed. It also goes without saying that none of this will succeed without logistics centers and the associated terminals. A high-capacity connection to the European railway network is also required since the route definitely does not end at the Bosporus. 

Crossing the Bosporus – a challenge no more!

The Bosporus Strait, which has been open to international commercial shipping since the 1920s, is one of the most important maritime shipping routes in the world. But while ships move freely in the north-south direction, the strait poses a geographic obstacle to traffic moving in the east-west direction. Plans for massive bridges were frequently discussed, but it took a long time before the first proper construction project was completed. It was in 1973 that the first of now three massive suspension bridges was opened. This was followed in 1988 by the Fatih Sultan Mehmed Bridge and in 2018 by the Yavuz Sultan Selim Bridge. Each of these is a technical marvel in its own right, with each design more brilliant than the last. But by the time the third bridge was opened, there had already been a tunnel under the Bosporus for some time. Yes, you read that correctly. A tunnel.

Marmaray Tunnel with the first freight train from China

In the meantime, another tunnel has even been added for car traffic, but it all started with the Marmaray Tunnel, which is the actual heart of the completely new Marmaray route. Since 2013, this rail connection has been the first direct connection between the continents with a standard track gauge. Hard as it may be to imagine, prior to this wagons had to be carried across by ferry.
A 1,387-meter long immersed tube tunnel now passes under the strait, 56 m below sea level. Eleven tunnel elements were preassembled and submerged at the site into a ditch previously excavated in the sea floor. After the segments were connected, the ditch was refilled. As the region is at high risk to earthquakes, the greatest attention was paid to safety, including the development of a custom concrete mixture. The construction costs of the project, which was started in 2004, were expected to be roughly €2.5 billion. As so frequently occurs with large construction projects, however, the tunnel went over budget, and the actual figures have been kept confidential. Nevertheless, the project is a great success story: due to the high level of local and long-distance traffic, the freight trains only operate at night. The first freight train from Xi’an to Prague passed through the 13-kilometer tunnel below the Bosporus in November 2019. The train was traveling on the trans-Caspian route, and it was followed by many more.

A new strait and an underwater tunnel with 3 levels?

Meanwhile the next gigantic prestige projects are building steam: For one, the government has announced to great fanfare the construction of a new ship crossing – a second canal alongside the Bosporus. This will be a project of the century in many respects but also receives a lot of criticism due to its expected high costs and terrific environmental impact. In the past years it already got postponed a few times.

On the other hand another tunnel is also to be added: 6.5 kilometers long, 110 meters below sea level, the “Great Istanbul Tunnel” will connect two continents and consist of three (!) levels. Two levels will be dedicated to automobile traffic, and the level between them will carry two railway tracks. The tunnel is planned to integrate the highways between Istanbul’s three airports: Istanbul Atatürk Airport, Sabiha Gökçen Airport and the new Istanbul Airport.
The travel times across the Bosporus are promised to be just over 40 minutes – a much needed relief according to data calculations from Istanbul’s transportation authorities, that the number of crossings between the European and Asian sides of the strait will exceed 3 million people per day in the future (current figures show a little over 2 million people a day).

In addition to the crossing between the two sides of the Bosporus, a high-capacity rail system is also being planned that will run from the west to the east of Istanbul. One of the world’s largest tunnel machines (“TBM”) will be used to excavate the Great Istanbul Tunnel project, with the giant drill measuring 83 meters in length with a 20 meter diameter.

In consideration of the current global situation and Türkiye’s tense economical state, it is hard to say at the moment whether these are anything more than just “daydreams” but it’s still worth to peen an eye open for those exciting projects.