At km 129, the canyon becomes narrow. The next tunnel uphill is the #34 whose exit is dug in the face of a vertical cliff, right in front of the famous "Puente Infiernillo" bridge.
It was always great to see color on a train as this southbound had. I like those red lights too.
Back and forth
This is the double switchback called Zig-zag Abajo and Zig-Zag Arriba. Abajo means down or below, and Arriba means up or above. These switchbacks are the only ones... (more)