The author offers a number of reasonsfor separating rail infrastructure from operations: toreduce unit costs, to create intrarail competition, tobetter focus on the services to be provided, to clarifypublic policy, and to strike a better balance between theroles of the public and private sectors. Moreover, recentexperience with "negative" concessions, in whichthe private sector provides public services (based oncompetition to provide the service and in return forcompensation), is adding another dimension to the"public vs. private" debate. In this senseseparating infrastructure allows new approaches to theproblem of meeting public responsibilities. Concessioningprograms in Argentina, Sweden, and the United Kingdom definethe broad alternatives in rail infrastructure separation.The two main challenges for separation are capacitymanagement and pricing policies. While it is true thatinfrastructure separation is messy and expensive, it will bea small price to pay if "fragmentation" offers abetter fit for consumers.