(Yesterday, 5:13 pm)Adrian wrote I think you may be reading it too literally. To me, they're suggesting that one train would start from Monkseaton, run round the loop via Washington, Sunderland and all the way back round on to the Airport. The train starting at the Airport would do the opposite, round the loop via Sunderland, Washington and then on to Monkseaton. It's marked in red because that bit doesn't exist; it presently goes back and forth between South Hylton and the Airport.
Even if you looked at it rationally, it'd make no sense to have a train that has travelled through Washington to terminate at South Hylton, then the trains from Sunderland to also terminate at South Hylton. Why would it be called the Washington Metro Loop in all official papers, if it's not a loop? It'd be a pointless level crossing (which NR hate and try to avoid), if it was never going to be used. You'd just build another platform at the other side of the road.
Plus, if the intention was to terminate everything at South Hylton, they'd use the existing curve alignment and terminate at Penshaw instead. It'd be a huge saving, as they they wouldn't need to build a new curve alignment and a couple of mile of track with no station - it may even become the longest section without a station on the system?
Aye no arguments about South Hylton.
But I personally read it as
3TPH | Airport - Sunderland - Heworth (Terminate)
3TPH | Airport - Sunderland - Heworth - Monkseaton
Why it's like that I don't know but the line from Monkseaton to Heworth on the red line is definitely only 3 TPH (narrow line), well and is says it on the side.