Jumping in here, this would be the "Northern Line" on the Merseyrail network. https://en.wikipedia.org/wiki/Northern_line_(Merseyrail) If the current fad of stop/start commuter lines continues this would be an excellent contender as it is at least rather scenic running from Southport through Liverpool (including an underground section) and then out to Hunts Cross. It would also be an excellent opportunity to chuck out another PEP variant with little effort needed converting the 313/314 to a 507/508. With the 507/508 fleets being retired now after 40 years of service it would be a great send-off to them and also give the devs an opportunity to introduce the new 777 rolling stock (for the modern player).
So I am late by a long time but the route has 36 stops I think and it's the class 777 and 507 what are not gona the peps but I think these 507/8 will be good for it riding up and down the Southport line or head bolt lane it will be amazing
