An empty Comanche coal train is lead by a rebuilt SD70MAC as it heads north towards Denver on UP's Main 2 track along Colorado's BNSF/UP Joint Line. In the foreground, a BNSF locomotive sits in the spur track of Spruce where it staged incase of a southbound train needs an extra motor to help it get over the hill of Palmer Lake. Generally, there are three "rescue motors" staged along the hill. Big Lift, Castle Rock, and Spruce are the locations where these motors are position to keep operations working smoothly on the 1.4% grade.