Proposal: Railways and Railroads
I would think that railways must be in professional section of topics rather than in recreational.
Looking at the description and example questions, this proposal seems geared more towards a hobbyist/enthusiast community than something being built by a professional organization or society.
I am a professional in railway signalling software, and have tried to post example questions that would be interesting to enthusiasts and other professionals.
I don't believe it really matters whether the site is marked as professional or recreational. Both groups of people will find the site wherever it is put, if they want to find it. Given that there are likely to be more enthusiasts than professionals joining the site, it might as well be left where it is.