Victoria Park Viaduct
The Victoria Park Viaduct is a major motorway viaduct carrying the Auckland Northern Motorway (State Highway 1) over the Victoria Park area in Auckland City, New Zealand. Due to the high traffic volumes passing through on their way to and from North Shore City, and because the viaduct is only four lanes wide in total (while adjacent motorway stretches are at least six lanes), the bridge over the park is considered "one of the country's worst traffic bottlenecks", with around 200,000 vehicles a day. After improvements to the Central Motorway Junction directly to the south in the early 2000s, Transit New Zealand, the highways authority, initially proposed a widening of the viaduct, which met with opposition from locals as well as from the Auckland City Council and the Auckland Regional Council, because it would further burden the Victoria Park area with more traffic and a larger overpass structure. In 2004 the authority agreed that instead of a second viaduct, the Vic Park Tunnel should be built, carrying northbound traffic only west of the existing structure, freeing it for southbound traffic.

Tunnel plans

Capacity extension
The new tunnel is to reduce congestion on the Victoria Park section of State Highway 1, an area where delays are becoming more common even in the interpeak between morning and afternoon rush hours. By providing more capacity, it will also ensure that the Auckland Harbour Bridge can be used to its full capacity. Originally called the 'Harbour Bridge to City' project, the official name has now become 'Vic Park Tunnel'. The tunnel, to cost approximately NZ$ 440 million (2009 estimate), will be a northbound-traffic carrying structure only, entering the ground in the area of the existing 'Birdcage' heritage pub (which will be relocated to allow the tunnel portal to be built in the area), and will reemerge to the northwest of the park where it will feed into additional lanes provided alongside the St Marys Bay stretch of the motorway. The tunnel will provide three lanes of traffic, and will be 440 m long. Construction is to last four years, starting in January 2010, after the new National government fast-tracked further state highways investment. The works at the northern end of the tunnel will including a pedestrian bridge over the widened State Highway 1 connecting the eastern end of Westhaven Marina and the Western Reclamation with the ' Jacob's Ladder' stairway linking to St Mary's Bay. The bridge, to cost up to $5 million, will span the 10 traffic lanes with a length of 100m, and is to be a 3.5m wide roofed structure with translucent design. While Jacob's Ladder access will be restored in time for the Rugby World Cup 2011, the new bridge will only be completed some time later.

Full undergrounding option
A future option to also bury the traffic lanes of the remaining southbound viaduct at a later stage was not ruled out. It was initially desired by the local stakeholders but did not go forward as the estimates for a replacement of the existing viaduct with a second/wider two-way tunnel envisaged costs of almost 50% over the cost of a one-way structure. Transit has noted that the existing viaduct might remain in use for a further 30 years before being replaced with a two-way tunnel structure. Auckland City and Auckland Regional Council however continued to call for an earlier burial of the whole motorway. They have also called for the 'Birdcage' pub (in the meantime bought by Transit) to be moved over the tunnel entry instead of beside it, to achieve a more attractive gateway and public space for the Freemans Bay community.

Interaction with harbour tunnels
The layout of any further traffic changes in the area will also be heavily affected by the plans for a possible second harbour crossing, which some plans see emerging at the Western Reclamation north of the tunnel, which is itself being replanned as a new mixed use and public park area. In May 2008, Transit New Zealand decided to revisit parts of the already consented plans to ensure that the Vic Park Tunnel design would not conflict with future harbour-crossing tunnels which were now short-listed to possibly connect Auckland City's Spaghetti Junction to North Shore City and would likely start in the area or run through it. Critics have however raised the question of whether the project should still go ahead when a second harbour crossing might eventually remove the need for the capacity extension that the Vic Park Tunnel is to provide.

As of early 2010, preparatory work near the St Mary's Bay onramp has begun. NZTA provide a project website. NZTA have also announced that the Birdcage hotel (sitting over the site of the future tunnel portal) will now be shifted 40m away only temporarily - eventually returning to almost the same site as before, and to become integrated into a new plaza space. In July 2010, NZTA announced that all services (pipes and cables) in the path of the tunnel had been successfully relocated, freeing up the construction zone up for all further works (works not hindered by such services have been proceeding for some time, and construction of the tunnel walls was to finish around middle of July). Around 160,000 m3 of soil will be removed in the 700m long tunnel trench, with over 100,000 man hours of work/month invested in the project, believed to be the highest of any roading project. The project is expected to continue until mid 2012, though it is hoped that the general structure of the tunnel, and all work requiring impact on local streets can be completed by the Rugby World Cup 2011. The Rob Roy Hotel was shifted into its temporary position at the end of August 2010, jacked up on sliding teflon rails and moved in a two-day exercise jokingly referred to as the "slowest pub crawl ever". It will eventually return to be relocated above the tunnel portal.