I’ve always loved horse racing terminology, this word in particular. Whenever a commentator mentions how happy all the ‘connections’ will be when their horse wins, I like to think that the punters form part of those too, not just the trainers, grooms and owners etc. Public transport is what gets most of us to the racecourses so this is a fun play on words. Plus, the coloured arteries of the tube lines made great equine veins!