http://www.pirate4x4.com/forum/showthread.php?t=931711 
As some of you may or may not know, the USFS has made a couple decisions on the Route Designation. 1) Rattlesnake Road will be now OHV legal. That's good. 2) The "Switchback" or "Billy Goat" trail, which is the oldest trail on the mountain, has been deemed after 100 years...as unsustainable.
Here's some facts regarding the trail and signal house: (Thanks to Hemingray)
The purpose of the lookout was to watch for fires in the snowsheds. The spark-belching wood-burning steam engines would cause fires and with so much wooden snowshed-covered track (it was nearly continuous from Emigrant Gap to Truckee), there was a lot at stake in catching fires early.
The Central Pacific built the first lookout in 1876, built of wood. In 1877, a telephone line was installed, from the lookout down to the agent at Cisco. In 1909, the stone structure we see now was built. It was only staffed in the spring through the fall as that was the primary fire season.
The lookout was abandoned in 1934 – and according to the USFS, the last man to staff the lookout was killed while talking on the telephone when lightning struck the lookout. It was abandoned as all of the locomotives were by then oil-fired (far less sparks), and improved snowfighting techniques allowed the removal of substantial amounts of timber snowsheds.
