The Metro have a Network Rail track access agreement just like a TOC does. There’s also freight on the route. Network Rail set the timetables and their signallers control the route between South Hilton and Pelaw on a day to day basis just like any other. There is a location where Metro trains can be looped and overtaken, but I haven’t heard of it being regularly used.
Metro times at Sunderland seem to run at a fairly exact clockface 12 mins apart in both directions, I’d assume therefore that there must be a potential path in between each Metro path for any other possible users of the line? In other words an hourly Northern service will leave Sunderland a few minutes ahead of a Metro, but not catch up the previous Metro before it turns off at Pelaw Metro Junction.
Realtimetrains shows how freight & mainline passenger services fit in in terms of overall running times.
So it seems at first glance Metro doesn’t need to be flexed to make space for other operators, so that just leaves what happens if something is late...
PS, they aren’t trams...
