Trains are more fuel efficient than air travel. This is true for freight as well as passengers. This article shows in charts who high-speed trains are taking market share from air travel by being virtually as fast but less expensive. That sends a market signal to choose the more sustainable option. Not to mention they are a lot more comfortable than the sardine cans we call airplanes these days.
Watch Out, Airlines. High Speed Rail Now Rivals Flying on Key Routes - Bloomberg