If you go exploring the ECML - London to Peterborough the Hertford Loop branches off at Alexander Palace and rejoins back just before Stevenage. Looking at the 2D map the route is already included and it just needs signalling and the scenery adding to make it look like a railway - it's already drive able and it would add interest in the line as both a local passenger route and a diversion from the main line. Most of the work has already been done Peter
