I know I don't understand the domain at all , but I'm surprised that in this day and age you'd want a distributed system to do railway design. What aspect of the problem makes it unsuitable for running in a single process?
Additionally, the UI contains complicated elements such as custom maps with the railway network and custom graphs to visualize trains. There is a large ecosystem to implement this kind of stuff via Web technologies. A webapp also removes the need to distribute an installable binary on many different platforms (some may be quite restricted due to company policies) and many different machines (there are many users, see above).
Note that the system uses a client-server architecture but isn't really distributed.