Australasia Railway Project: "Darwin's position as a transport and logistics hub, supporting the mining, oil and gas, tourism, agribusiness and Defence industries. The Northern Territory Government sees the AustralAsia Railway as fundamental to the Territory's future development, as outlined in its Foundations For Our Future strategy released in 1999.
The railway will also complete a landbridge linking Adelaide and Melbourne with North Asia, providing an efficient and competitive link from Asian markets to the south of Australia."

a couple of good outline maps of the project