Wellington's bus drivers are on a winning streak.

The Employment Relations Authority has ruled in their favour, defining a 'work period' as from when drivers first sign on, to their last sign off, irrespective of split shift arrangements.

It means the time used to calculate their break entitlements now includes the time splitting the shift.

Tramways Union Secretary Kevin O’Sullivan says often it will mean drivers will get another rest break, which makes a massive difference.

He says fatigue is a significant problem in the industry especially for people working up to 14 hours.

It comes after union members accepted a pay and entitlement deal with NZ Bus last week.