But if my family of four wants to take an outing to S.F. then the same trip costs about $10 roundrip to drive, versus $46 to buy four full-fare roundtrip caltrain tickets.
Is it reasonable then to deduce that public transit is not an economical alternative for more than two people commuting the same route? I have a friend who lives in S.F. and works in P.A. and for this reason he carpools rather than take the train; that and the fact that it would take him much longer to get to the 4th & King Station and then get to work (by bike) from the P.A. caltrain stop; than to take his car eve in HWY 101 traffic!
Since caltrain engines run on diesel, they are probably subject to the same fuel costs as cars so higher oil prices will drive up caltrain prices.
Bottom line: Available public transit is not an alternative to driving between S.F. and P.A; not economical nor practical.