In my experience, the vast majority of HOV/carpool lanes are single lanes, although some stretches like the 110 and the 91 are doubled up and are a much better

In my experience, the vast majority of HOV/carpool lanes are single lanes, although some stretches like the 110 and the 91 are doubled up and are a much better experience. It's hard to believe the 405, of all places, is a single HOV lane and it bunches up pretty much continuously. Although, on the 91, I don't know that it uses transponder settings since there's a dedicated "3+" lane when you approach reading areas, which are situated right in front of CHP buildings (so they can see if you're really 3+?)