Work to strengthen the Auckland Harbour Bridge was due to start on Sunday.
The New Zealand Transport Agency, which has replaced Land Transport and Transit, says work on the clip-on lanes on either side of the bridge, will take 2½ years.
About 760 tonnes of steel will be welded and bolted onto the box girders.
The northbound lanes are being strengthened first, with closures of the clip-on lanes and Curran Street on-ramp at night, and restrictions on heavy vehicles.
