@Edmund and
@IanBertram both have points about the Metro. Partly, it might be down to differing ages. My dad started using the Loop in 1970 when at college in Newcastle and living in Whitley Bay, and my brother still uses it to get to work now - including literally today, from Fellgate to Northumberland Park - so our familial memory covers some ground.
The diesel multis being used in the 1970s were pretty knackered, and not really suitable for the route. They didn't have the acceleration to get to speed between the closely packed stations. This made them slow, and caused reliability issues. Plus, the stations were falling to bits, especially the Tynemouth/Whitley Bay/Cullercoats trio on the coast. But all of them were grotty and run down. The Metro changed all of that. Services were faster, more frequent (every 8-10 minutes, rather than every 20-30), cleaner, and went to stations that weren't derelict. The whole thing was a vast improvement. Especially before bus deregulation, as the transfare system fed bus passengers into the system at places like Heworth and Gateshead in an integrated fashion.
But that's 40 years ago. During the later 90s, the bus system stopped working with the Metro for the greater good. The next blow was when the Sunderland/South Hylton extension opened in 2002(?), they had no new units, so service frequency went down. To every 12 minutes, on average. Which meant every 6 between South Gosforth and Pelaw, where both lines run. 5 an hour isn't really enough for "just turn up" on the bits outside that core stretch, so it's no longer as good as it once was in place like the North Tyneside loop or the South Shields branch.
However, I (just about) remember the service on Pelaw- Sunderland before the Metro. We'd either walk to Brockley Whins and get the train to town or drive to Jarrow and use the metro. I believe the trains were four an hour. But two of those only stopped at Heworth between Newcastle and Sunderland. Which means Brockley Whins, East Boldon and Seaburn got two an hour. Pacers, in the main. And good lord, if ever there was track not designed for pacers, it was the curves at the Gateshead end of the bridges over the Tyne. Noisy, smelly, scruffy, poor ride, bus seats (until a refurb in the early 2000s, I think, but even then the seats were crap). Plus, had they been running what were now Metro lines, they would have still had the poor acceleration issues that plagued the DMUs.They would not have been an improvement on anything the Metro was offering North of the river, or to Shields. Indeed, very few on the Sunderland line (even ignoring those who use the additional stations like Fellgate, St Peter's and SoL, or beyond Sunderland to Hylton) would say that it was better when it was heavy rail.
Of course, the Metro stock is now 40 years old, and struggling. As is some of the infrastructure. But 40 year old Metro stock is a better ride in pretty much every way than 20 year old pacers were. And those buggers lasted until forty elsewhere.
I believe there's infrastructure investment to accompany the new units arriving from Switzerland. Hopefully that will help to improve reliability and stop the fatal "all fall down" problems which seem to be ticking upwards.
