An Auditor-General's report on the performance of the NZ Transport Agency says it needs to know more about the state of all its bridges and tunnels.
The state highway network is valued at $29 billion.
The report is critical of the agency's long-term road network planning and makes recommendations for doing the job better.
It says NZTA needs to improve the quality of the information it holds on its assets.
It also says the agency needs to be more focussed and systematic in its planning for maintenance and renewal work.
NZTA says it has now updated its asset management plan and expects to have fully addressed all of the recommendations by the end of the financial year.