Morning peak 10s, 47s and X45s bound for Newcastle use the “Centrelink” to avoid the congestion on Redheugh Bridge, St. James Boulevard, Plummer St & Railway St. They’re able to serve Gateshead & Newcastle Quaysides as a result.

X66s bound for Gateshead Interchange can use the Centrelink which is especially helpful in the morning peak as it avoids the congestion on the approach to Redheugh roundabout.
(There was a period where the closure of Rabbit Banks Road (due an apartment development) prevented this however it reopened as soon as the scaffolding was able to be cleared from that narrow stretch of road). 
Since the Askew Road Bus Gate greatly reduced traffic congestion on Askew Rd, it’s been quicker for X66s bound for Metrocentre Interchange to use Askew Rd, rather than heading in the opposite direction to snake down to Pipewellgate to reach the Centrelink.

‘Centrelink’ presumably was named so as it helped buses LINK MetroCENTRE to Gateshead Town CENTRE.