The Big Istanbul Tunnel

Big Istanbul Tunnel in 10 Questions

Turkey is getting prepared for the big tunnel project which will connect two sides of Istanbul by rail and road. Here are frequently asked questions about the project:

Where it’s going to be constructed?

Big Istanbul Tunnel is planned to be constructed between first and second Bosphorus bridges, under Bosphorus.

The Big Istanbul Tunnel Route
The Big Istanbul Tunnel Route. Map: Transportation Ministry

Why “big”?

One of the other tunnels under Bosphorus, Marmaray Tunnel, where railway is passing through has a diameter of 7.89 m. The other one, Avrasya Tunnel, has two storeys only for cars, and a diameter of 13.7 m. Big Istanbul Tunnel is planned to have a diameter of 16.8 m. The reason is that the tunnel will have 3 storeys.

What’s the difference between tunnels?

Marmaray Tunnel has only railway pass connecting Sirkeci to Uskudar. The railway is connected to national rail network which allows not only suburban trains, but also freight and passenger trains.

Avrasya Tunnel is now under construction, connecting Harem to Yenikapi. It’ll only for car traffic.

Big Istanbul Tunnel will be both for car traffic and metro line. The top and the bottom is for one-way car traffic and middle storey for double-track metro line.

Big Istanbul Tunnel
Big Istanbul Tunnel. Picture: Transportation Ministry

Why is there a need of new tunnel?

The other tunnels are connecting the transport corridors next to Marmara Sea. However, the main transport corridor of Istanbul connecting denser residential and commercial areas is in the north. Thus, the new tunnel is expected to lighten both the metrobus traffic and the car traffic of both bridges.

What’ll be the route of metro line?

The metro line passing through the Big Istanbul Tunnel will start from Incirli (Bakirkoy), go along E5 under metrobus line, change direction towards Arnavutkoy from Meciyekoy, pass under Bosphorus, cross Cengelkoy towards Altunizade, and follow again metrobus line reaching to Sogutlucesme.

Why metro under metrobus line?

Metrobus rapidly becomes the best solution on main transport corridor of Istanbul, and is running over capacity. This metro will run on the busiest section of metrobus line.

What’s the cost of project?

The project is expected to cost USD 3.5 bn.

Avrasya Tunnel, with 5.4-km-long 2-storeys tunnel and 9-km-long connection roads costs about USD 1.3 bn. Big Istanbul Tunnel has 6.5-km-long 3-storeys tunnel and 9-km-long connection roads and tunnels. And there’s also a 31-km-long metro, but it’s not clear if this cost is included in this amount.

Is this amount already included in investment budget?

No, there’s only budget for preliminary analysis. It’s expected to be constructed by “build-operate-transfer” method. It’s not clear if the metro will be constructed with the same method or not. If done, it’ll be the first private metro of Istanbul.

Is there a contractor which can afford build-operate-transfer?

Daily usage of Avrasya Tunnel is expected to be between 90-120k, and could find a contractor for build-operate-transfer method. The capacity of Big Istanbul Tunnel will be the same. But cost is 2.5 times more. And financing is harder nowadays. These may cause problems in tender. State support/share would not be suprising.

But many companies already appiled for the tender on 23rd of December?

Since the tender on 23rd of December is for preliminary analysis. This works will be paid by state for preparing the project after analysing the route and ground. Terms of conditions of the tender for construction will be defined after this analysis. The preliminary analysis is expected to last at least one year.

Related Articles:
Will Big Istanbul Tunnel Help Traffic Congestion?
The Big Istanbul Tunnel Project
13 New Rail Lines for Istanbul
Urban Transport by Rail in Istanbul
Completely False Facts About Marmaray

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