The purpose of this paper is investigating the privatization feasibility for construction of infrastructures in railway network. The private sector into two different domain, can take action to resolve capacity in the Railway networks.The first domain with participation of the private sector in projects of improvements capacity of existing railway network infrastructure. The second domain is with participation of the private sector in projects of construction of new railway infrastructure. In this study, in order to determine the feasibility of the project devolving problems capacity to private sector peresent new methodology. The proposed methodology based on problem solving capacity with two different point of view. The aim of two point of view (local and network performance) is resolving capacity problems in railway network. But, Tactics used in two point of view is different. In the present study three basic questions answered. Question one: Which of the two Point of view of local and network performance are more appropriate to resolve capacity problems? Question two: Is it possible regardless of construction of new railway infrastructure only by improving capacity of existing railway network infrastructure, capacity problems that will resolve in railway networks? Question three: If a country's policies upstream rail system, construction of new railway infrastructure is considered essential in country's policies about railway system. Which the construction of new railway infrastructure is a higher priority and feasibility to be devolving private sector? The proposed methodology in capacity problem solving feasibility based on economic analysis. Economic analysis is performed taking into account the direct and indirect interests. Evaluate the proposed methodology done with considering that Iranian railway network. Railway demand matrix and railway network as input parameters were considered the proposed methodology. Capacity bottieneck were found according to incremental assignment and all or nothing assignment. Identify capacity bottlenecks done according to bottleneck intensity index and concept of fundamental Bottleneck that proposed in this study. In consequence peresent concepts, resolving capacity problems divided into two part. The first part considering construction of new railway infrastructure. Construction of new railway include building Esfahan-Azna, Esfahan-Ahvaz, Garmsar- badrood, Yazd-Aghlid, Gorgan-Mashhad. The second part considering improving capacity of existing railway network infrastructure. Improving capacity of existing infrastructure include double-track railway, Fix blocking system in railway, railway electrification system, reopen closed stations, increased axial load, send long train.