Work to extend the life of Wellington's 80-year-old Mt Victoria Tunnel will close the tunnel for five nights a week until early 2012.
From May 9, the tunnel's firefighting systems will be upgraded and earthquake strengthening will be carried out between 8pm and 6am, Sunday to Thursday.
"It's essential the upgrade is done efficiently. Closing the tunnel five nights a week is the best way to do this without affecting peak time traffic flows in and out of the city," NZ Transport Agency (NZTA) acting highways and network operations manager Mark Owen said.
The tunnel will remain open during Rugby World Cup games played in Wellington, he said.
Two alternative routes will be available, one through the suburb of Newtown and another around the bays. Pedestrians will need a specially issued bus card to access transport on free buses.
The Terrace Tunnel on the other side of the city will also be closed overnight in conjunction with the Mt Victoria work.
The upgrade will be carried out by the Wellington Tunnels Alliance, a consortium including the NZTA, Leighton Contractors, AECOM and SKM.
