Pusher Service! A 2-8-0 pushes a mixed freight westbound up the 1.5% grade.
Interestingly, the Curve was built on a series of wooden bridges, which were then "back-filled with dirt," taken from the digging of nearby Brush Tunnel. At one time the Curve was double track. Details taken from http://www.american-rails.com/helmstetters-curve.html and supplemented by Jason Vance.
For other shots from the WMSR Foundation/Lerro Productions WMSR photo charter, go here.