[WS:] We seem to be talking past each other. I agree with your answer A, since more people drive than fly. However, my comments about flying was a response to Joanna's posting about opportunity costs of flying and taking the train. The idea I argued was that opportunity cost of flying would become higher if the train alternative became viable and that would change the behavior of some air travelers. That was it. I did not say that it was the main reason for building HSR in CA. The only reason I actually gave was that it is an "environmentally correct" solution - which may or may not be factually correct - but it is at least consistent with your A answer.
I also gather that you do not dispute my argument that changing the opportunity cost structure of flying will lead to some behavioral changes, but what you do dispute is whether the number of people changing their behavior this way is sufficient to justify capital intensive projects such as HSR. I do not disagree with your position. Given that the ratio of air miles to driving miles is about to 7:1 http://www.bts.gov/publications/national_transportation_statistics/html/table_01_40.html, it is obvious that much greater returns can be obtained by providing alternatives to driving than to flying. However, I still think that short distance flying is a bad idea for environmental reasons (it is more polluting per mile than long distance flying) and for that reason alternatives should be provided even if the number of people involved is not that great.
Moving beyond cost/benefit considerations - I think that our economy is sufficiently productive to provide many good and beneficial things, regardless of what their cost benefit ratio is. We do this in some areas. We provide health care to terminally ill patients or retrieve bodies of soldiers KIA because these are the right things to do, not because of utilitarian considerations. In fact, doing those things makes little sense from the utilitarian perspective, yet most people would find if extremely offensive if utilitarian reasons were cited to cut these activities. My wishful thinking is that we use the same logic to other services, such as transportation, education, environmental protection, housing etc. Using utilitarian rhetoric to deny or cut these services is a part of neoliberal propaganda to frame the public debate, which I find offensive and I believe it should be vigorously opposed.
Wojtek