A high-speed train is about 40% the speed of an airplane.
So a 1 hour flight is comparable to a 2.5 hour train ride. However a quick check shows that, on average, it takes over 2 hours (133 minutes) to get on the plane after you've arrived at the airport. Then of course you've got to get off the plane, but we'll be generous and not count that time.
In summary, taking the train is about 30 minutes faster than flying. As for cost, well, the emissions from flying make the cost somewhat irrelevant. Any reasonable government would tax flying so it's more expensive than rail travel.
So a 1 hour flight is comparable to a 2.5 hour train ride. However a quick check shows that, on average, it takes over 2 hours (133 minutes) to get on the plane after you've arrived at the airport. Then of course you've got to get off the plane, but we'll be generous and not count that time.
In summary, taking the train is about 30 minutes faster than flying. As for cost, well, the emissions from flying make the cost somewhat irrelevant. Any reasonable government would tax flying so it's more expensive than rail travel.