Those a mucky definitions. Roads are excludable in just the same way as trains... you don't have a car, you can't get on roads. That's economic exclusion, and a bigger excluder than transit fares in most urban settings (not to mention requiring a license, no DUIs, etc).
A good transit system has very low fares, as they try to include everyone even the poorest people. A good transit system also has very rarely full trains, and more coming along in 5min if that one's full.
If you're arguing that roads are a public good, then you absolutely must accept that transit is one... and any rational person would agree that they are a far greater good than roads and highways (at least, within the urban centers).
There was exactly one definition in my comment: that of a public good. The remainder was my reasoning for why roads and trains do not fit that definition of a public good. With which part(s) do you disagree?
"If you're arguing that roads are a public good..."
I'm not arguing that. That's why I started my comment with "No, they're not".
I'm not sure how to respond to the rest of your comment, as your main point (that public transit is good) is orthogonal to mine.
A good transit system has very low fares, as they try to include everyone even the poorest people. A good transit system also has very rarely full trains, and more coming along in 5min if that one's full.
If you're arguing that roads are a public good, then you absolutely must accept that transit is one... and any rational person would agree that they are a far greater good than roads and highways (at least, within the urban centers).