About the Hejaz railway:The Hejaz railway was a narrow-gauge railway (1,050 mm , about ( 3 ft- 6″) in track gauge) that ran from Damascus to Medina, through the Hejaz region of modern-day Saudi Arabia, with a branch line to Haifa on the Mediterranean Sea. The current global standard railway track gauge is 4 feet 8.5 inches (1,435 mm) , used by about 60% of the world’s tracks. The completed Damascus to Medina section was 1,300 kilometres (810 mi). It was the only railway completely built and operated by the Ottoman Empire. Complete rebuilding estimates for the historical 1,300-kilometer Hejaz railway from Damascus to Medina range extensively depending on the scope, with broader regional revival initiatives cited at over $200 billion