sandiegoprestressedconcretecompany

I think believe this to be Rohr San Diego Prestressed Concrete. These appear to be the prefabricated concrete columns for the Pearlridge monorail in Hawaii. The logo on the tractor cab door says, "SDPC."

The flatbed trailer says, "Matson" and "intermodal system," suggesting it may be going on a ship.

Truckers call flatbed trailers, "skateboards," because they look sort of like a skateboard.

This is a good photographer as the clouds masked out the sunlit San Diego Prestressed Concrete location while the background is dark and under cloud cover.

The coordinates 32°52'40" N 117°10'28" W should plot to the bridge over the railroad track at lower right.

This aerial photo just happened to catch what looks like a northbound AmTrak passenger train going under the bridge. The track was still Santa Fe as the BNSF merger had not yet occurred. The Coaster commuter trains did not exist in 1974.

They still used conestoga wagons drawn by oxen in 1974. 😄 Kidding about the wagons.

This construction site appears to be on the north side of Imperial Avenue near 15th Street in San Diego. The pole line along the street in the background may be along Imperial Avenue. You can help by posting comments if this is wrong. You can also add tags if you see something in this scene that some guy using a search engine could be looking for.