The Asian Infrastructure Investment Bank (AIIB) will provide funding of up to USD 1.5 billion for the construction of a new railway line between the Asian and European sides of Istanbul. The corridor will cross the Bosphorus via the Yavuz Sultan Selim Bridge and link the city’s two major airports.

Asian Infrastructure Investment Bank – AIIB and the Government of Turkiye have signed the first phase of a financing package of up to USD 1.5 billion for the Istanbul North Rail Crossing – INRAIL project.

The investment involves the construction of a new, double-track, electrified railway line, equipped with modern signalling systems, between Çayırova, on the Asian side of Istanbul, and Çatalca, on the European side.

Trains will cross the Bosphorus Strait via the Yavuz Sultan Selim Bridge, which opened to road traffic in 2016 and was designed from the outset with space reserved for a future rail link.

The project documentation indicates a length of approximately 122 km, whilst the AIIB press release refers to a corridor of approximately 127 km.

The line will allow passenger trains to travel at speeds of up to 160 km/h, whilst freight trains will be able to travel at 80–120 km/h.

The project will directly link:

The new main line will bypass the congested central areas of Istanbul and complement the existing Marmaray rail crossing, which runs through the tunnel under the Bosphorus.

One of the project’s main objectives is to eliminate the bottleneck affecting rail transport between the two parts of Istanbul.

At present, freight trains’ passage through the metropolis is limited by the capacity of the Marmaray corridor and the need to share infrastructure with busy passenger services.

Following the opening of the new line, the time taken by freight trains to travel the Çayırova–Çatalca route is expected to fall from approximately 13 hours to 3.6 hours.

Separating part of the freight traffic from suburban and inter-city services should increase both the capacity and reliability of Istanbul’s rail network.

The new infrastructure will also create a direct rail link between Istanbul’s main airports.

The journey time by public transport between Istanbul Airport, located on the European side, and Sabiha Gökçen, on the Asian side, is expected to fall from approximately 120 minutes to 65 minutes.

The line will integrate the two airports into the national rail network and facilitate connections with Turkiye’s intercity and high-speed trains.

The total cost of the investment is estimated at approximately USD 8.27 billion, making INRAIL one of the largest rail projects currently in the pipeline in Turkiye.

The AIIB will finance the project alongside:

The project will be carried out under a design-and-build contract, and the selected contractor will finalise the technical solution and environmental documentation.

The route will largely follow the corridor of the existing motorway, but the works will include tunnels, viaducts and railway sections built from scratch.

The World Bank has classified the project as one with substantial social and environmental risks.

The corridor passes close to sensitive areas, including the Sariyer–Feneryolu wildlife protection area, the Ömerli reservoir and several nature reserves.

Potential impacts include land acquisition, the resettlement of some residents, loss of vegetation, noise, vibrations and disruption to communities during the construction period.

The project will affect 53 localities in the provinces of Istanbul and Kocaeli, and the authorities must draw up plans for compensation, resettlement and the protection of the livelihoods of those affected.

Once operational, the new railway crossing over the Bosphorus is expected to reduce emissions by approximately 16 million tonnes of CO₂ equivalent over the entire operational period analysed by the funders.