Tehachapi Loop

Built just before the turn of the century in 1878 by migrant Chinese workers, the Tehachapi Loop enables a 77 foot elevation gain in a small valley by snaking the line in a complete 360 loop – dramatically increasing the run over the rise in order to maintain no more than a 2 percent grade.

3000 workers carved this trail by hand out of solid granite.

Only freight trains run this line today. There’s a live Webcam on the loop with nice desert ambience sounds – when there’s no train passing thru, which happens about 36 times a day!

https://en.m.wikipedia.org/wiki/Tehachapi_Loop