Wellington's primary route into the city will be closed for 12 hours tonight for roadworks.
Both lanes of State Highway 1 between Thorndon and Ngauranga will be closed from 10pm today until 10am tomorrow while work is carried out to connect an old off-ramp to the Thorndon Overbridge.
The southbound lane will also be closed between 10pm tonight and 6am tomorrow.
It is part of the Transport Agency's $50 million Smart Motorway project due to be completed next year.
The agency's acting highways manager Mark Owen said the closure had not been taken lightly and it was being done overnight to minimise the impact on the public.
Motorists will be able to use the Hutt Road while the highway is shut.