The park to park comparison is the opposite of what's being discussed. That's comparing the value of apple to another from the same tree - there are many subjective elements to compare but given that they're both nearly identical it's quite easy. Still doesn't fit on a spreadsheet e.g. bitterness, likelihood of having a worm inside, prettiness, whatever.

What is being suggested is comparing a train subsidy to... Unknown. Other modes of transportation? The money being spent on other carbon reduction efforts?

I don't understand why carbon reduction is the primary topic for discussion when trying to put a dollar value on the thing. Two apples are still a little difficult to compare but you at least can agree that the bigger tastier one is probably better value (unless the smaller is cheaper and you need to do gram for dollar value, idk, good luck). A train vs other things though is imo essentially impossible to compare, a genuine apples to oranges comparison.

For carbon reduction, I challenge the OP estimate. It assumes everyone drives if no train, as I understand it. So that's the carbon reduction comparison - wow great so many people not driving. But it's not just that. Less parking lots need to be constructed. Less concrete, less carbon. Less roads need re paving every 10 years or whatever - let's compare the carbon of rail maintenance to an asphalt road. Less car accidents, less cars needing to be recycled at plants. Maybe city designs start accommodating the train subsidy, less car centric design, more vertical and dense, less car travel that wouldn't have been served by the train but is now served by walking. On and on and on.

You can't compare these two on carbon alone, and that's not even considering the fact that I find it kinda ridiculous to focus on just carbon as a measure of worth-to-humans. There's so many other factors at play that I genuinely think it's impossible to put a dollar value on. Reduction in road noise for people near the highway. Reduction in smog and thus a reduction in lung cancer and related medical costs. Reduction in human deaths from car accidents. Increase in psychological happiness in commuters not exposed to daily road rage and also suddenly having more time to read or play games. Endless, endless comparisons.

Dollars are a bad way to measure value. We either need a new way to describe value-for-dollars or a new way to describe actual value. Conflating the two was capitalism's ultimate coup and this thread is a great example of why.

This analogy simply doesn't work because transit isn't fungible. Trains and air travel or cars simply aren't "the same park". The benefit of trains is objectively not just the carbon footprint. The money spent by the government benefits the public in other ways, not just environmentally. Ignoring the wear on (and cost of ownership of) personal vehicles, for instance, dismisses a huge amount of savings for folks who can take trains instead. Rail travel is safer and results in fewer deaths. The list goes on. Even "having a train that takes me to work so I can relax on my commute" is an important one. And many of those things are almost impossible to truly quantify the monetary value of and jam into a spreadsheet.

I didn't say that. The OP argued "Actually this is bad because the cost per ton of carbon saved is higher than some other way to save carbon."

The original replyer pointed out that "ways to save carbon" are not necessarily fungible and there are other benefits to subsidized rail travel. The followon dismissal was to throw back and come up with a way to "price" those other benefits.

What I am objecting to is the entire chain of thinking that starts with trying to do simplistic, reductionist price comparisons and then refusing to consider other factors that don't fit in the pricing exercise.

Yes, because that is exactly how American cities are currently built today -- expensive carbon-intensive roads paved out to sprawling suburbs, the independent financial upkeep of which is not sustainable long-term. [0]

The costs for car-based infrastructure are also sky high: $1+ million per mile of new road, excluding constant maintenance in repavings, potholes, and drainage systems. [1]

From an economic lens, transportation infrastructure is a net gain to the economy. To me, there is no reason why public transit subsidies should be scrutinized on financials above and beyond how public roads are scrutinized.

If we recognize roads are useful, then public transit should be an even more efficient use of taxpayer dollars on mobility per infrastructure footprint costs alone -- even before carbon reductions are considered at all.

---

[0] https://www.strongtowns.org/journal/2021/5/12/6-principles-f...

[1] https://www.strongtowns.org/journal/2020/1/27/how-much-does-...

Here's an alternative proposition then: try those things and if there's demand - stick to them.

No need for estimations, especially that they're typically wildly off, as the world is too complicated to summarise it on a spreadsheet.

The cost of something is not related to what it is worth to life. In any case the real measure is what someone is willing to pay. I'm driving a 25 year old car because I choose to buy a more expensive house, and put my kids in various activities - as a result I don't have enough money left over to pay for a new car. I do have enough money to pay for a used car when the current one breaks and is unfixable, but I have choosen to spend elsewhere - those used cars provide exactly as much value to me as a new car and save me money. (I save even more money by riding my bike where possible so I rarely drive)