Ankara–Istanbul high-speed railway is expected to extend to Istanbul New Airport by overpassing Bosporus strait. But, will this route pass through Marmaray suburban rail corridor?
According to the web page on Wikipedia, we can see the sentence "Along with commuter trains, high-speed and intercity trains will also use the tunnel along with limited freight service."
In addition to the fact that it's making a detour, local trains are running at 8 minutes interval. Under this condition, it will be difficult to operate freight trains and high speed trains.