I went down into the archives last night and pulled the original photo of Ralph P. Merritt, head of the Metropolitan Transit Authority, and our 1958 rapid transit plan. The map is labeled "Mass Rapid Transit Projection for Los Angeles Metropolitan Area."
I made a large scan of the map so everyone can try to read it. The original isn't terribly clear (after all, this photo was only a graphic element and never meant to be used as a map) so I'll interpret the labeling:
This map is broken down into "Major Radial Service" and "Major Circumferal Service." In other words, the entire transportation plan is seen as a wheel with spokes radiating from a central hub, which is--as you might expect for 1958--downtown Los Angeles. The circumferal route describes the rim of the wheel and the radial routes constitute the spokes. This design, by the way, is how the origin and growth of the city's streetcar system was described in 1923: Spokes of a wheel radiating from downtown Los Angeles. The only difference then was that the "wheel" had no rim.
The radial routes are:
1. Hollywood and the San Fernando Valley
2. Pasadena, Pomona, San Bernardino and Riverside
3. Fullerton, Santa Ana and Whittier
4. Long Beach and San Pedro
5. Santa Monica
The circumferal routes are:
A. Airport, Coliseum and Beach Cities
B. Burbank and Glendale
C. Lakewood and Santa Ana
D. Santa Ana and San Bernardino
E. Downtown Los Angeles / Central Transit System
F. Fullerton and Santa Ana
Comments, insights? Let me know. Surely there must be some transportation experts who'd like to venture an opinion.