> Where there is enough population density and 'right of way' for trains, trains almost always make sense. You will come really close to that if you build a ro

> Where there is enough population density and 'right of way' for trains, trains almost always make sense. You will come really close to that if you build a road that has the same level of right of way, and drive buses. The benefit of (expensive) bridges and tunnels are not unique for trains. Some of the subway trains in Paris run on rubber tires.