That depends why units are underutilized, though. If the train + bus system doesn't get you close to where you need to go, it might not be worth your time to us

That depends why units are underutilized, though. If the train + bus system doesn't get you close to where you need to go, it might not be worth your time to use. If it takes too long, again, won't be worth the time. If they can't get you to work on time or stop running before you are off work? Again, not worth your time to use them. In all of these cases, a good answer is to have more convenient public transport - and that usually means adding more units. Other problems have other solutions, like adding tolls to congested areas, subsidizing public transportation so the fares are low enough for people to afford or choose it over driving, or increasing private vehicle ownership costs.