The head end of the Zephyr is just about to duck in Tunnel 1, having gained a few hundred feet since crossing Blue Mountain Road just out of the frame to the left. CO-72 heads up Coal Creek Canyon to the top-right.
Interestingly, when David Moffat was building the line in 1902, one of the possible routes surveyors considered would have taken the tracks straight up Coal Creek Canyon, where CO-72 disappears in the background. This would have necessitated a long tunnel (to get from present day Crescent Village to Pinecliff). It was largely due to this the railroad opted to instead take the current alignment along the Front Range to South Boulder Creek.
