Our best estimate is that a single rail would cost about the same as a 2 lane paved road or about 2 million per mile for rural installations and about twice that for urban installations. The rail would only carry traffic in one direction but it would have about the same capacity as four lanes of freeway.
The real savings, however, comes with maintenance. The maintenance costs for a paved road accumulate so that by the time 40 years has passed the road has effectively been replaced with a new road. This gives paved roads a lifespan of 40 years. In contrast, the rails in our design would last for centuries and require little maintenance. The the reason is because the rails would be made out of magnesium oxide (MGO) based concrete rather than Portland cement based concrete. The Great Wall of China, the Coliseum in Rome, and the Pantheon also in Rome, all owe their longevity, at least in part, to MGO cement.