This publication is a continuation of the work undertaken in Phase 1, and extends its analysis to the following areas: Technical and legislative aspects, Socioeconomic analysis, Conditions for the establishment of national and international networks, and Financial and planning elements of HSR. The development of an HSR network in the TER region would significantly improve the competitiveness of rail, increasing the sustainability of the transport sectors in TER countries. Currently, there are few railway lines in some TER member States that allow high-speed operation. This creates a unique opportunity for developing HSR systems in individual TER member States while ensuring that this development is integrated across the wider TER region through adequate international connectivity. This study aims to provide decision-makers with the necessary tools to define what, if any, HSR networks should be developed in their respective states.