Amtrak Acela, Boston - NYC is $173 one-way and takes 3 hours and 30 minutes. That quickly adds up.
It might not be rational, but we pay a lot more in taxes to make it seem like traveling is far less expensive than it actually is.
Several states impose a fuel tax that's below their sales tax limit. They still need to pay for road maintenance.
"U.S. annual gasoline consumption is 140 billion gallons and growing." The federal tax is 18.4 cents per gallon that's 25.76 billion a year but you need to subtract out the oil company subsidy's, NHTSA's billion a year for safety, federal reconstruction aid after a disaster etc, and not just the new federal construction costs.
While 'free parking' is available in large sections of the country it still takes land and someone needs to maintain it. However, it's vary unusual for federal, state, or local governments to pay for such parking as part of a gas tax, it's generally taken from the budget of the agency providing that parking space.
Anyway, I responded to someone making a very specific claim about federal spending so I responded to that, state spending is a far more complex issue so here are some numbers:
http://www.taxadmin.org/fta/rate/mf.pdf
Do you really think Alaska magically get's by on 8 cents a gallon or are the diverting funds for somewhere else to pay for roads? They don't have a sales tax so the math is easy on that one.
But, now let's look at Wyoming it has a nice 4% general tax on everything and charges 14 cents a gallon for gas. Let's say gas is around 3.25 a gallon before taxes and at 4% would wait for it be 13 cents. Do you think that single extra cent is going to pay to maintain all their roads? Because if the tax was 12 cents a gallon clearly they would be subsidizing that relative to you buying say cheeseburgers and they don't exactly have a lot of toll roads. Then again, if they spent close to the same percentage on road maintenance as people did on gas then the numbers would work out just fine. But wait for it, they don't.
If you happen to live by Omiya's station (about 30mi closer to Sendai), you'd be there in under 2 hours.
If even the English can do public projects better than you, you have a problem!
NYC always has several big tunnel projects going on. The problem here is the very hard granite and the depth of existing infrastructure. New tunnels have to be very deep. At the moment I believe there is a large east-side subway project and a water main project. There was supposed to be a new west side tunnel for Amtrak and NJ Transit trains coming into Penn Station from NJ, but unfortunately NJ's ahole governor killed the project.
I'm not familiar with tunnelling projects in Philly and DC, or the areas between them. I suspect the terrain is a lot more varied than below the Channel though. It'd be challenging to tunnel the whole way.
Beijing to Shanghai, for example, is currently averaging 186mph, and if they get back to initial goals, they'll average over 200mph.
http://en.wikipedia.org/wiki/Beijing%E2%80%93Shanghai_High-S...
In short, NYC to Boston should be 90 minutes by train.
Taking into account travel time to and from the airports, plus time spent in security, you might be looking at longer than 3.5 hours.
Still, travel along the Northeast corridor would be a lot cheaper if those fares didn't have to subside ridiculous cross-country routes. A one-way ticket from New York to Los Angeles (changing trains in Chicago) costs $266 and takes 62 hours, not including the 5 hour layover. Why are these trains still running?
There are also strong network effects in play. NYP to BOS is great if you're just going from NYP to BOS. But if you're going from NYP up to Portland, or BOS to Trenton or Pittsburgh or something, the cheap NYP-BOS connection is useless to you unless there are also not-extremely-expensive links from NYP or BOS to your actual endpoints. Part of what makes NYP-BOS so cost-effective as a route is that it's also fed by other lines that A) exist and B) aren't prohibitively expensive.
A political reason is that the keep-Amtrak-alive coalition is basically a mixture of urban transit advocates and representatives from rural areas who want to keep their town's train stop. A system that only served the major cities wouldn't have broad enough support, especially if it were only the major coastal cities (e.g. if you cut the Chicago, St. Louis, Pittsburgh, etc. services).