Work will include the addition of steel beams to the bridge's structure to make it suitable for use by heavier vehicles, including 50-tonne trucks.
New Zealand Transport Agency (NZTA) Otago senior network manager John Jarvis said that there were no present safety or strength issues with the bridge, and 50-tonne trucks did not use the bridge at the moment.
''Tenders close on February 10. It will take probably a couple of weeks before we award it [the contract]. We would hope to have work under way early March and completed by the end of June.''
Most of the work would be done beneath the bridge.
There would be some disruption to traffic during work, Mr Jarvis said.
''Large steel beams have to be put in underneath and will have to be welded, and while that is being done there is likely to be single-lane traffic,'' he said.
During the reinforcing work separate work to clean up damage caused by pigeons would be carried out, if possible.
The NZTA would work closely with the Central Otago District Council when conducting the bridge strengthening, Mr Jarvis said.
Because the bridge was on State Highway 8, it was the responsibility of the agency, rather than of the council.
Work on two other bridges in the Kawarau Gorge was also about to start, he said.
They were the Gentle Annie and Kawarau Victoria Bridges, on State Highway 6 between Cromwell and Queenstown.
