If you look at costs such as noise, just as monetary costs they will still exist, but be nearly an order of magnitude smaller. Take a single double-track train

If you look at costs such as noise, just as monetary costs they will still exist, but be nearly an order of magnitude smaller. Take a single double-track train route. Its capacity will be 3x or more a massive freeway, take up a tenth or less of space. If you were to put traditional freeway-style sound walls around it, it would probably be quieter than the freeway. Tire noise is massive.