Returning to West Boulevard Bridge, I believe this is one of the images that was used in
Engine54's videos. It shows the demolition of the original, temporary bridge. It doesn't look like there was much room for automobile traffic on the left. If you zoom in, you can seen the name "Vineyard" on the large pole in the center.
USC Digital Library
Like the picture above, this one is also dated vaguely at 1930-1960. I'd say that everything looks pretty new, and there's no moving traffic, so I'm guessing it's quite early. You have to look harder for the "Vineyard" sign in this picture - it's on the first pole after the bridge. It's a shame that the dividing wall, which matched the design of the bridge, has been replaced by a wire fence.
USC Digital Library