I'm currently making in the Nether a two lane railway between my portal and (0,0) it is at a depth of 100 for the rail height. Problem is the amount of Nether rack required to make bricks then blocks... approximately 7 blocks/fences a m means 28 blocks of nether rack.

The track will be 200m square when it is finished. So to complete just one side requires about 2800 cubes of netherack (I only create fire resistant blocks for air zones with ghasts... which is about half the track length).

I've got a nether rack brick maker with a charcoal maker attached to the side... all I need to do is feed in wood and nether rack and then empty out the nether bricks.