Traffic management restrictions are on the horizon for Auckland's Harbour Bridge

NZTA says it's been strengthened as much as it can be.

The addition of any more steel to add strength would be counter-productive, because of the additional weight it would bring.

Waka Kotahi general transport service manager Brett Gliddon has told a parliamentary select committee that vehicle management will have to be used.

He says there are multiple options, including restricting the movement of heavy vehicles.

Brett Gliddon says it won't be needed in the next 12 to 18 months, but will be required sooner than in 20 years, as stated in a briefing paper to the Transport Minister in November.