Comment by solatic

> capacity constraints make it difficult to have significant competition

Thirty years ago, you would be correct. In the modern day, you could tie switch signalling to real-time auctions and let private rail's command centers decide how much to bid and thus whether or not they win the slot for putting their cars onto the shared rails. The public rail owner likely needs to set rules allowing passenger rail to pay a premium to secure slots in advance (say, a week) so that a timetable can be guaranteed to passengers during peak rush hour, but off-peak slots can and should be auctioned to naturally handle the difference between off-peak passenger rail and not-time-sensitive, more-cost-averse freight rail.