The Mount Victoria tunnel in Wellington is to be upgraded to a cost of about $50 million.
The Transport Agency says work on the 80-year old tunnel, including earthquake strengthening and upgrading firefighting systems, will begin next month and be completed early next year.
The agency's acting highways and network operations manager, Mark Owen, says the upgrade will bring the tunnel's systems up to modern standards and extend its life.
Mr Owen says there will be some disruption to the public, with the tunnel closed five nights a week while the work is done.
Work will halt prior to the Rugby World Cup and resume shortly afterwards.
