There haven't been any new freeways constructed in metropolitan Los Angeles for about 25 years now - the last new corridor was I-105, which has offside shoulders and was at the time the most expensive road built in the USA. You are right that some freeways have had central reservations repurposed to accommodate HOV lanes, for example the elevated HOV route down the middle of the Harbor Freeway.jackal wrote: ↑Wed Oct 13, 2021 10:24Many D5+ Los Angeles freeways have no inner carriageway, interstates and state/US routes alike. I'm not up on the construction dates of relevant sections of the I-5 or I-405, for instance, but suspect the rules allow for some compromise with the reality of limited space and ever growing traffic - indeed I suspect offside shoulders may have been constructed and then reclaimed, often for HOV lanes.
Most of LA's freeway network predates the interstate system, the first length (the Pasadena Freeway, then US-66, now CA-110) opened in 1940, with southerly extensions opening in 1953 (south of US-101 is now signed as I-110) The Four Level in central Los Angeles (the world's first 4 level stack) opened here in the same year. These corridors are now looking very antiquated in comparison to recent routes.
However, LA is not a poster child for good highway design given the appalling weaving between junctions, overreliance on non-standard layouts with frequent 'wrong side' entry and exit slip roads, poor directional signage, and endemic congestion because LA is too big and uncomfortable to travel anywhere except by car given the near desert temperatures during the day.