Second Harbour Crossing, Auckland

In 2019, about 170,000 vehicles were crossing the bridge each day, including 11,000 trucks and more than 1,000 buses.[15] The following statistics were for the 7–9am morning peak period:[15]

• 38% of all bridge users were bus passengers
• 58% of bridge users bound for Auckland CBD (not to the south or west) were bus passengers
• 20,000 people travelled in cars to the CBD (unchanged for 25 years)
• 53% of car users were travelling past the CBD to southern or western destinations
• 11,000 truck crossings rising rapidly and expected to reach 26,000 in 2046

A paper published by the New Zealand Transport Agency said that with private vehicle crossings static due to congestion on feeder roads and with the rise in public transport crossings, it would make more sense to drop the road-plus-rail proposal and build a rail crossing only. With freight volume and number of trucks rising, heavy rail might be justifiable, rather than a light rail passenger service.[15]

Several solutions have been proposed in the past, including building another bridge alongside the existing one, a tunnel, or combinations of both. Following a detailed scoping study undertaken in 1996, Transit New Zealand identified its preferred options for a new crossing - either a new bridge approximately 500 m west of the bridge connecting to the North-Western Motorway (SH16) via a tunnel underneath Ponsonby and Grey Lynn, or a tunnel slightly to the east of the bridge connecting to the Central Motorway Junction via twin cut-and-cover tunnels under the western CBD / Victoria Park.[16]

In 2006, Transit New Zealand noted that its 10-year plan, at that time being consulted on, would include funding for another study into a second harbour crossing.[17] This study was declared to include the possibility of landing a future tunnel underneath the Tank Farm, with a connecting tunnel to south of Victoria Park. Costs are estimated at NZ$3 billion.[18] Some commentators like Brian Rudman have noted that it would make the most sense to keep the new crossing for public transport only, possibly to connect with a rail tunnel to Britomart Transport Centre.[19] This statement was largely supported by North Shore City mayor George Wood, who noted that public transport provision on the new crossing (including the possibility for light rail or heavy rail to connect to Britomart) had been part of North Shore City Council's plans for many years.[20]

A possible tunnel between Mechanics Bay and Northcote was also to be considered in the feasibility studies, but faced increasing criticism from local groups, as well as problems due to the denser residential zones and geographic difficulties faced on such an alignment.[21]

In December 2007, Transit New Zealand noted that the more than 160 options had been narrowed down to only two alignments. The first possible alignment (of approximately 4.5 km length) would be a parallel link several hundred meters directly to the east of the existing bridge (either as a bridge or a tunnel), while the second alignment (of approximately 6.5 km length) would start in the same general environs in North Shore City, but travel diagonally southeastwards to link up with the motorway at Grafton Gully, east of the Auckland CBD. The second option, due to the need to cross shipping lanes, would need to be a tunnel. It could also possibly be connected to the CBD via a side branch tunnel (for use by public transport only).[22] North Shore City has noted that it would prefer a tunnel option for aesthetic reasons, and to potentially emplace light rail within the tunnel at a future stage.[23]

A tunnel had been proposed as early as 1920, during discussions about extension of Auckland's rail network.[8]

In mid-2008, the Waitematā Harbour Crossing study group released their recommended option (2C), which would connect from the existing Esmonde and Onewa motorway interchanges on the North Shore City side to Auckland City, reaching land in the southwestern part of the Western Reclamation (though the links may continue as tunnels for some further distance, likely going under Victoria Park). The option selected from several hundred considered alignments foresees four separate tunnels, two for motor vehicles and two for public transport.[1] Due to the reduced costs of narrow-diameter tunnels driven by modern tunneling methods compared to providing similar capacity in one or more large tunnels, this option was considered the most economic. The characteristics of the recommended options are:[1]

• two motorway tunnels (three lanes northbound in one tunnel, three lanes southbound in the other), carrying State Highway 1
• two public transport tunnels (rail in the recommended option), connecting Britomart with a new North Shore City rail system
• demolition of the Victoria Park Viaduct and deemphasising of the Auckland Harbour Bridge for some through routes
• provision of a new rail station for the future Wynyard Quarter at the southern edge of the new development
• an estimated cost of NZ$3.7 to NZ$4.1 billion, though the links could be built in stages, reducing immediate costs

The study also assumes that by 2041, the volume of trips over the harbour will increase by 80% from current (2000s) levels, and estimate that the public transport share on the link would rise from a current 15% to then 30%.[1]

In mid 2009, NZTA was reported to be preparing land designations for the tunnel option, to safeguard the route and ensure progress on the Western Reclamation did not negatively affect the future tunnel and vice versa.[8] Transport and Associate Infrastructure Minister Steven Joyce also noted that a decision would be made in 2009 as to whether the crossing would be included in NZTA's new 20-year plan.[24] On 2 December 2009, NZTA announced that designations would be protected for the four-tube tunnel option, though funding to build them was not currently allocated in the budgets, and no future date for construction was announced.[25]

During the public discussions in 2007, an interest group put forward a proposal to build a new, much larger bridge to the east of the existing harbour bridge, and demolish the latter. They argued that the new bridge, which would be about 50% longer than the existing one, could be constructed to provide for dedicated public transport (including light rail, which they claimed would allow a tripling of the total capacity in people then being moved over the existing bridge), as well as for cyclists and pedestrians. Significantly, they argued that the new bridge would more or less pay for itself, by freeing up new residential land occupied by several kilometres of motorway approaches in some of the most sought-after Auckland locations like Saint Marys Bay. The proponents claimed that the bridge would free up more than 35 hectares and open up 3.3 km of shoreline, a prize which would more than make up for the fact that the plans for the Western Reclamation redevelopment would in this case find themselves partly compromised by a major motorway in its area. The proposed bridge would also be cheaper to operate, and unlike a tunnel, would not need emission vents.[26][27]

The proposed bridge design, a cantilever spar cable-stayed bridge, was put forward by the Jasmax architectural firm, which noted that the 'Anzac Centenary Bridge' would be buildable in time for the 100-year memorial of the Gallipoli landings in 1915.[26]

Some attendees at a 2009 bridge conference held by the NZ Transport Agency in Auckland remarked that a bridge would be more beneficial to Auckland in some ways, and would have reduced operating costs compared to a tunnel solution.[28]

In October 2009, the bridge option again surfaced in the public eye, with a group of backers again suggesting that a bridge would be a better option from an urban design, and even from a transport point of view. Critics noted that the proposal would delay other transport plans in the region due to the funding required for it, especially for a 2015 target.[29] The then mayor of North Shore City, Andrew Williams, and the then Chairman of the Auckland Regional Council, Mike Lee, both opposed the reconsideration of existing decisions that had been in favour of a tunnel. The then mayor of Auckland City, John Banks, also favoured the tunnel option, though he did not outright oppose the bridge idea, while the then mayor of Manukau City, Len Brown, considered the bridge proposal worthy of consideration.[30]

The more detailed concept the bridge group proposed in late 2009 included eight traffic lanes (including separate truck and bus lanes), two light rail tracks (in the bridge deck) as well as walking and cycling paths, possibly with travelators. Backers claimed that the bridge, estimated by them at NZ$2–3 billion, would be significantly cheaper than a tunnel for approximately NZ$4 billion.[31]

In December 2009, it was announced by NZTA that designations would be sought for the tunnel options, though it was noted that this did not have to preclude a future bridge option, but was solely an exercise to protect the tunnel possibilities against conflict with future development in the Western Reclamation area.[25] The lobby group for the bridge option regarded as a success the fact that the transport minister did not preclude it, though their original timeframe was also modified, now aiming for a construction start by 2015.[5] In March 2010, tendering for a new study was announced, after Minister of Transport Steven Joyce apparently instructed NZTA to reopen the bridge/tunnel debate. The decision of the minister was criticised in an editorial in The New Zealand Herald for wasting time and money, since the previous study had already, at cost of over $1 million, conclusively ruled out a bridge as a good solution.[32]