New Zealand Transport Agency media manager Frances Adank said on Wednesday the bridge was undergoing a "major strengthening and maintenance programme" unrelated to the flooding issues in the South.
The work is expected to continue until the end of April.
"For the first three weeks, there will be closures of up to 30 minutes at a time.
"These will be every hour, on the hour between 8am and 5pm weekdays.
"As the work programme progresses so will the closure types, including some overnight full road closures."
Ms Adank said the work was "heavily weather dependent" and more specific details about the effect of the work on traffic would be released weekly.
Pictured is one of the entries in the 2015 vintage and veteran car rally, that marked the 50th anniversary of the Vintage Car Club of New Zealand’s first international rally in 1965.
