Have bus/rideshare "stops" on the side of freeways, where say I could drop off a rideshare who would then catch their employee shuttle, just like shuttles pick people up from train stations. You could also pick up your regular carpool at one. I had the idea on the way to work, remembering that some Samtrans buses have stops on the side of 101, and wishing I had a carpool buddy for the carpool lane.
Pro: easier picking up / dropping off of carpool buddies
Con: might well mess up traffic as you'd have people stopping and starting around there. Maybe a side road could exit off the freeway and re-enter right away to make it work better.
Back to taking Caltrain tomorrow.