I would argue that high speed regional rail would address this as well. How many flights from regional airports to major hubs could be eliminated with a decent train?
For example: Spokane to Seattle is about 230 miles in a straight line, or 280 miles driving. A flight takes less than an hour (not even 40 minutes of which is spent in the air) and costs $80-130 one way. A train traveling 200mph nonstop would take 1 hour 24 minutes. Building high speed rail costs $20-$200 million per mile (the upper end of that is California HSR). If we optimistically assume $20m/mile, constructing the line will cost $5.6b. If all SEA-GEG passengers (677k per year) choose to take rail instead of flying, and we want the project to pay for itself after 50 years, then each ticket will need to cost $165. This also assumes no cost to maintain or operate the rail line.
I wonder if we could not get most of the benefit by doing substantially cheaper options like separating freight from rail on major routes, electrifying parts of it where feasible. And maybe taking specific segments in areas where the track conditions are already favorable and increasing the maximum speeds on those segments. Probably two-thirds of the route between Portland and Salem, for example, is already suitable with modest upgrades to hit 125 mph. And basically all modern trains are capable of that speed already.
whyfor? I guess I don't know how I would price "get there faster" in a reasonable way.
> separating freight from rail on major routes
that does seem to often be the limiter in North American passenger rail, but I don't know how economically feasabile it is to separate the two. I assume railroads are moderately expensive to maintain.
Trains, even HSR have essentially zero hijacking risk relative to airplanes, and proper safety interlocks make them very difficult to use the vehicle as a weapon.
At that point, your terrorism risk is approximately on level with any other dense transportation interconnect.