What a wonderful layout! I have only just discovered your blog, and thoroughly enjoyed catching up with it.
I have often thought that Kelvinbridge would make an excellent prototype for a layout. Tunnels at both ends, and the sort of intensive train service that many models of rural branch lines seem to enjoy! As part of my undergraduate studies, I wrote a dissertation about the history of The Glasgow Central Railway, and have often wondered whether it could be expanded into a book. I doubt that it would interest many people, and I'm a lazy so-and-so, so I very much doubt that it will happen. Whilst at uni, my girlfriend (now wife) and I had a flat in Kensington Gate, and we often used to walk the old GCR lines, particularly around Maryhill. Happy days! As you say, there was a large amount of coal for domestic consumption handled at the various (above ground) stations. Though I haven't seen any photographic evidence, one very elderly chap that I made contact with assured me that during the summer months, as the coal was stockpile in readiness for winter, the piles were whitewashed in order to prevent, or at least show, any pilferage. He also said the he remembered, during WW1, the Royal train being berthed in the tunnel between Kelvinbridge and Botanic Gardens, with soldiers posted at each end in order to protect King George. The Royal Train running through Partick - that would be something different!
As a point of interest, how big is your layout? I am almost tempted to divert my modelling interests from the Southern Railway to the Caley!
Keep up the superb work,
Xavier Onassis