The Trans-Australian Railway crosses the Nullarbor Plain from Port Augusta in South Australia to Kalgoorlie in Western Australia. It includes the world's longest stretch of dead-straight railway track, a 478 kilometre length between the 797 km post west of Ooldea and the 1275 km post west of Loongana. The line forms an important freight route between Western Australia and the eastern states. Currently two passenger services also use the line, the Indian Pacific for its entire length and The Ghan between Port Augusta and Tarcoola.