Considering the vintage of the original photo (around the same time that the Cabrillo Freeway was being built), this would make Route 94 and Route 15's freeway presences in the area a lot older than I had ever suspected...
http://www.johnfry.com/pages/PhotoRozelle03.html
when did they reconstruct the interchange away from the clovers? When they doubled the width of 94, is my guess, and what year was that?
here I had thought that 15 freeway dated back to 1950... perhaps it's earlier than that?
Looking at the bridge log...
http://www.dot.ca.gov/hq/structur/strmaint/brlog/logpdf/logd11.pdf
The basic crossing of the two freeways was completed in 1951, while the interchange there today dates back to 1959 (but reconstructed in the mid-1990s somewhat).