Analyzing the railways network
Certainly it is possible. For example, in the following study the Indian railway network was analyzed. 

Small-world properties of the Indian railway network. 
Parongama Sen, Subinay Dasgupta, Arnab Chatterjee, P. A. Sreeram, G. Mukherjee, and S. S. Manna. Phys. Rev. E 67, 036106 – 2003

In another study, the Chinese railway network was considered. 

W. Li, X. Cai, Empirical analysis of a scale-free railway network in China. Physica A: Statistical Mechanics and its Applications, Volume 382, Issue 2, 2007, Pages 693-703. 

The main problem is probably obtaining good data sets. However, train time tables are public, so in principle you could use data from any available time tables to reconstruct the network topology. If you also want the spatial embedding (the geographical coordinates), those might be more difficult to obtain.