Thanks Tim McDaniels for supplying this photo showing the service road bridge being placed as construction on Glen Canyon Dam nears completion in 1964. The back of the photo reads:
“Glen Canyon Unit: Girders for the right abutment service road bridge being lowered into place by the two 50-ton high lines.”
The concrete batch plant is still standing on the left side of the picture, but its days are numbered. Click on the photo and zoom in to see the details. These old black & white USBR photos have incredible resolution. Click the photo for a closer view.