Auckland's $340 million Victoria Park Tunnel will open to some traffic today.
Transport Minister Steven Joyce says the development will remove the last remaining major bottleneck in central Auckland's motorway junction.
Two lanes will open to traffic today while the third lane will open to northbound traffic in March next year.
Mr Joyce said the tunnel would greatly ease congestion for the 150,000-plus vehicles that use the route each day and would eventually reduce journey times by to 20 minutes.
