Ansco’s Rio Grande Ski Train approaches Big 10 Curve between Rocky and Clay, Colorado, on the morning of August 4, 2001. Summer editions of the passenger train operated to Winter Park for hikers... (more)

AMTK 76 (P42DC) rounds the Big Ten Curve as it leaves Denver and the Front Range behind. Soon the California Zephyr will be climbing through the Colorado Rocky Mountains on its way to Emeryville,... (more)

The Big Ten Curve enables UP 6049 (AC44CWCTE) to drop further in altitude, winding through the 270 degree switchback which keeps the grade change at 2%.

UP 6049 (AC44CWCTE) leads a coal train through Big Ten Curve as it drops in elevation towards Arvada, Colorado.

Union Pacific’s manifest freight from Salt Lake City to Denver drops fills “Little 10 Curve” at Rocky, Colorado, on the afternoon of February 13, 2016. In the foreground is the main line and... (more)

Union Pacific’s MRONY manifest freight from Salt Lake City to Denver drops downgrade through Big 10 Curve west of Rocky, Colorado, on the afternoon of February 13, 2016. In the foreground is the... (more)

BNSF 4978 (Dash944CW) leads an oil can train down Big Ten Curve as it heads to the BNSF yard in downtown Denver.

The cows pay no attention to the California Zephyr which is climbing through Big Ten Curve on its way to the Colorado Rocky Mountains.

The Rio Grande Heritage unit made its way back to the Moffat Sub. the first week of the new year. The previous day the train only made it from North Yard to Rocky before the lead units had mechani... (more)

Amtrak’s westbound California Zephyr climbs toward Big 10 Curve between Rocky and Eisele, Colorado, on June 2, 2013.

Union Pacific MRODV (Roper Yard in Salt Lake City to Denver) freight passes a coal train in the siding at Rocky, Colorado, as it departs for Denver on April 29, 2001.

The California Zephyr rounds Big Ten Curve as it heads to Denver.

UP 6720 (former Chicago & Northwestern AC4400CW) pulls a coal train through Rocky, Colorado. In the background is the National Wind Technology Center at the National Renewable Energy Laboratory i... (more)

AMTK 74 (P42DC) pulls the California Zephyr around the tight radius of Big Ten Curve. The row of trees you see are lined up against a row of hidden loaded coal cars, which have been placed there ... (more)

Union Pacific’s West local out of Denver climbs Rocky Spur at Rocky, Colorado, on January 18, 2001. Powering the local is a trio of Rio Grande GP40-2s—Nos. 3121, 3100 and 3111. Below is EMD SD... (more)