(5 hours ago)DodgepotMcDougal wrote It coped as it had capacity. That capacity no longer exists

I'm glad you have clarified it coped with more passengers than it does now with fewer. 

Quite how it won't cope now, with an increase that won't be to the level it was then, is open to debate.

Class 555.
Total capacity of 544 (336 seats and 752 standing. 

Class 599.
Total capacity of 504 (128 seats 376 standing). 

40 more people on the new stock vs old stock. 

The core frequency during de-reg was a headway of 10mins.
With the new stock, the headway is supposed to be 10mins.

During the 1985–86 financial year, the Tyne and Wear Metro carried a total of 59.1 million passengers.
During 2023/24, 30.7 million passengers used the metro.
Larger trains with scope to cope with another 30million passengers.

Im quietly optimistic it will cope. Just like it did 40 years ago.