Before the UP 150 Express Train was backed into the California State Railroad Museum for the 150th Anniversary Celebration event, two of the three auxiliary locomotives, #8715 and #8775 (seen here on the bridge), were repositioned to the rear of the train during a series of switching operations at the wye located just south of the American River Bridge.
This photo shows UP 844 and #7947 moving towards the wye as they initiate the switching sequence.
