Saw this on another forum… the Wallah Gorge Spiral on the 2’ gauge Namtu Bawdin BCL mine railway. Steam powered trains narrow gauge trains, with a tight helix that makes 1.5 turns. The pics are copyrighted so I’ll just post the link to the page they’re on:
http://www.freerails.com/view_topic.php?id=6209&forum_id=43&jump_to=68264#p68264
There’s also a shot of a neat little rail truck going over the stone arch bridge on the helix.