An amazing amount of elevation is gained as the railroad climbs the front range of the Rockies west of Denver on a two percent climb to the Moffat Tunnel. With the rear of a Union Pacific coal empty far below, the head end is about to knock down the signal at East Eisele, Colorado, on June 2, 2013. All of this height gain is due to the remarkable engineering exploit of Big 10 Curve, which the train is climbing through.