Like with roads rail requires a lot of maintenance if you put the heavy load on it. Having to shut down the transport periodically isn't good for business. Per

Like with roads rail requires a lot of maintenance if you put the heavy load on it. Having to shut down the transport periodically isn't good for business. Perhaps with containers on rollers it is possible to replace one without shutting everything down. Kinda interesting puzzle, the rollers should fit in the containers. A telescope would make them to weak, picking up the old roller, rotating 90 degrees, bringing the new one, rotate 90 degrees, drop it in place.