Doesn't make sense. Switching the road to steel increases cost when the road is not in use because you're building a single-use roadway. Predominant costs here are land acquisition costs. If you can't split land use among multiple users, you're hosed.

Just think about it. You're starting a company and the first thing you need to do is spend a few billion dollars before you move your first ton? Doomed company.

This is the classic problem with rail: you need to plan the route so you have sufficient participants willing to fund development, you need to acquire land (which you can't safely do piecemeal because the guy down the line will extort you).

I take your point, but that requires long-term planning and alignment of a lot more people and organisations, all of whom have their own messy incentives.

I'm trying to think of solutions that can be mostly built by the private sector and deployed with only modest legislative changes.