THE southbound Teven bridge on the Ballina bypass opened on Tuesday, but the northbound bridge won't be open until January.
This means southbound Pacific Highway traffic won't use the Teven interchange roundabout, but travel over the bridge and merge to a single lane about 200m north of the Bruxner Hwy intersection.
Ballina Bypass Ready Taskforce chairman Glenn Costello said it was disappointing both bridges couldn't be opened before Christmas.
Motorists travelling north from Grafton will continue to use the existing road and then access the Ballina bypass at the Teven Rd interchange.
The speed limit will be cut to 60kmh on the newly-opened section while the road surface settles.
This will be reviewed as part of the next phase of the upgrade early next year.
Electronic signs will be in place to warn motorists of the speed limit change and guide motorists through traffic changes.
Ballina MP Don Page warned motorists could still expect queues over the Christmas/New Year break at Ballina's northern and southern entrances despite the bypass.