The OPEC Fund for International Development has approved a $250 million loan for the Istanbul North Rail Crossing project, marking the largest single financing commitment in the institution’s history.

According to a statement from the fund, the loan is part of a broader approved financing package of up to $500 million for the construction of a new railway bypassing the Istanbul metropolitan area, The Caspian Post reports, citing Anadolu Agency.

The 127-kilometer (79-mile) double-track, electrified railway will run between Cayirova on Istanbul’s Asian side and Catalca on its European side, crossing the Bosphorus via the Yavuz Sultan Selim Bridge.

Designed to carry both passengers and freight, the line will address a major bottleneck in rail traffic between Asia and Europe. Currently, freight trains can use the Marmaray tunnel only during limited nighttime hours, restricting annual freight capacity to 3 million tons.

The new railway will increase that capacity to 50 million tons annually and reduce freight travel time between Cayirova and Catalca from 13 hours to 3.6 hours.

The project will also connect Istanbul Airport and Sabiha Gokcen Airport to the national railway network, cutting transit time between the two airports from two hours to 65 minutes.