Auckland harbour bridge is not on a list of 300 bridges throughout New Zealand that are to undergo strengthening work.
The bridge's absence from the list has come to light as officials weigh a proposal to allow bigger trucks on highways, which would require bridge upgrades costing $85 million.
The Transport Agency says Auckland harbour bridge was left off the list because consultants qualified to carry out specialised engineering assessments were not available.
The agency says a detailed analysis will be carried out later in the year as part of a process of assessing state highway routes suitable for heavier vehicles.
It is possible these vehicles may be restricted to using the Auckland upper harbour route, via State Highways 16 and 18.