This Union Pacific eastbound led by no. 9507 is about to enter the Aspen Tunnel located east of Evanston, Wyoming. The parallel Altamont Tunnel is just out of sight at right on the far track. Although this and the preceding slide might imply that the Aspen Tunnel was used for eastbounds and the Altamont Tunnel for westbounds, both tunnels were signaled for bi-directional traffic.
