mtbc | Hidden mysteries of the Clockwork Orange (Reply)

I sometimes wonder about quite how they organize Glasgow's subway system. For example, I had guessed from service frequency that they often have as many as four trains running on each circular line. Is one train allowed to leave a station until the train ahead has arrived two stations ahead? Or, maybe it need only depart the next. I don't know how they guarantee separation. I have also wondered how they manage various situations, for example, what if a train breaks down? I suppose maintenance is centred partly on ensuring that they don't in a manner that unexpectedly blocks the line and strands the passengers. It's hardly a wide tunnel.

I have noticed that it's not uncommon for the outer line to pause at St Enoch while the driver pops out for a minute. There's also talk of a depot, one morning (last month, I think) the subway wasn't running because the line from the depot was icy, suggesting some track that isn't underground. Recently, I happened to spy an exciting clue: travelling on the outer line from, I think it was, Ibrox to Govan, I glimpsed a line branching off along another tunnel then rejoining a little later. I wonder what other side tunnels there are.

A bit of googling suggests that they can have as many as six trains running per circular line, though I wonder how typically that actually happens. It also suggests that the tunnel I saw may be a branch to the not-submerged depot so perhaps the inner line also has a branch in the same segment.

Incidentally, Glasgow has an excellent transportation museum which includes a couple of older subway carriages and is packed high with exhibits. Last time we visited, it even had Imperial military folks from Star Wars happy to pose for selfies with visitors. Dundee's transportation museum is funnier in offering modest but quite random mystery tours on an old bus.