13 - Marmaray tunnel - WikimediaRailway Infrastructure

Can freight trains pass through Marmaray tunnel?


In a couple of months, Turkish national network in Europe and Asia will be connected through Marmaray tunnel.

The motto of the project is “connecting China to UK” and official statements involved passing of freight trains throught the tunnel. Despite those, many still hesitate.

Here are the main reasons of hesitation:

Limited time

Marmaray suburban trains run between 06:00-24:00. The third line on surface that freight trains will use, will be used by high speed trains and passenger trains during day. Thus freight trains can only run between Gebze and Halkali within that 6 hours. That hours are also for inspection of the line. Freight trains will cross 76-km-long stretch in about one hour.

Curve is too sharp

There’s a sharp curve in the tunnel between Uskudar and Ayrilikcesme. Radius is 301.5 meters. However this is not extra ordinary for freight trains. 20% of the rail curves in Turkey are between 200-500 meters.

Gradient is steep

The gradient between Sirkeci and Uskudar is 17.7‰. Freight trains can overcome that. Turkish network has gradients over 20‰.

Marmaray is not built considering freight trains

The idea was crossing the freight trains from the beginning. The 3rd line is built based on this idea.

Dangerous goods should not be transported through city and tunnel

Dangerous goods will not be allowed in Marmaray route. Uncovered goods are also not expected to pass. For those kind of goods, ferry will continue to operate.

Freight trains should not run on high speed lines

Technically it’s possible. Bursa HST line is also being constructed accordingly. All further HST projects in Turkey is planned to allow freight trains. The main difference of HST lines is the cant to decrease centripetal force on curves. However curves are not many on Marmaray stretch and speed of HSTs and freight trains will be similar. The lines that are being used by freight trains should be inspected carefully.

Marmaray tunnel is not suitable for freight trains

There are other rail tunnels in world where freight trains can pass through. However unlike others, Marmaray is an immersed tunnel. Thus some think that vibration of freight trains can be dangerous for such a tunnel. A freight train has a gross weight between 1000-1300 tons. The axle load is up to 22.5 tons. Marmaray suburban trains weigh 723 tons when full, axle load is 18 tons. HSTs weigh between 400-550 tons, axle load is 17 to.

Cover photo: Wikimedia CC BY-SA 4.0 ©

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