Amtrak No. 5, the California Zephyr, finishes encircling Big 10 Curve and approaches the east switch of Clay siding on the afternoon of October 23, 2011. This long 10° curve uses a mesa and 2 percent grade to allow the railroad to continually gain enough elevation so to eventually enter the Flatirons and South Boulder Canyon at a proper height and gradient. Remarkable engineering! That hopper car windbreak has worked so well over the years that it is almost completely obscured by trees from this angle, and is located directly above the train. The few trees and grasses in this area of Colorado’s front range are showing the last colors of autumn and we will soon be entering another season.