As the design team leader of the SkyPath project and originator of the SeaPath, I've researched the costs and benefits of the various alternative harbour crossings over 10 years.
The most feasible and cost-effective solution is simply to build a new bridge.
Rather than locations east of the Auckland Harbour Bridge, I suggest that a new bridge would be best extending on the western side for northward traffic, keeping well away from Wynyard Quarter, whilst retaining the Auckland Harbour Bridge for southward traffic giving the two eastern lanes 7m wide for walking, cycling and lookouts (adding wind and rain protection) continuing seaward all the way to Esmond Rd.
Going on recent examples, such as the 2.5km long Gordie Howe bridge in Detroit due to be finished in 2024, the cost of a new bridge will be significantly less than the tandem currently being concocted, and it would be a more worthwhile addition to the Waitematā.
Since picking up the Labour Government's pledge to build the popularly backed Skypath/Seapath,the smart lightweight composite design that had been thoroughly peer reviewed, costed at $50m and achieved resource consent in 2016, the NZTA has embarked upon a strange odyssey with its delivery.
Four years later, the plans for Seapath now follow a convoluted inland route at $250m, and, in the place of SkyPath, we have a new concept visualisation design of a standalone boxy-looking steel bridge for pedestrians and cyclists, with an estimated cost of $685m and very little else.
Little wonder organised storming of the Auckland Harbour Bridge by cyclists and walkers is back in the news, creating all sorts of divisive controversy.
To future-proof and provide a backup crossing, the NZTA earlier ambitiously proposed a tunnel under the Waitematā. This would be a massive project, somehow entering through the regenerating Wynyard Quarter and daylighting somewhere around Esmond Rd to then merge with traffic coming off the Auckland Harbour Bridge which would be retained.
Back in 2012, the cost estimate for the tunnel crossing was $4 to $5 billion. Last heard, that had spiralled upwards to $10 billion.
A new state-of-the-art bridge would head westwards from Pt Erin/Westhaven, stepping across Curran St and the reef, then beginning to curve before Watchman Island and sweeping out to acknowledge the channel before hooking back into the stem of Northcote Pt, with a short 250m surgically inserted tunnel through to the east to emerge seamlessly into the northern motorway past Sulphur Beach.
As it would be longer than the Auckland Harbour Bridge the gradient would be less of a
climb. Passage for trams, walkers and cyclists could be alongside or perhaps sheltered better beneath.
The actual form of the bridge could be quite simple, the curved form with a series of long legs would be restrained and elegant enough to fit the outstanding surroundings.
A good example of such a curving bridge is the pre-stressed concrete and steel girder Coronado Bridge in San Diego, which is five lanes wide and high enough at 61m to allow the US Navy Pacific Fleet to pass under.
As to figuring what NZTA's endgame of all of this is, my guess is that if we accept the new pedestrian bridge, then the ground will be cleared for the underwater tunnel to get the green light.
Do the taxpayers want to be saddled with a $10 billion invoice?
Perhaps now, with all the public stress around on how best to cross the harbour, the time has come for this to be reviewed and something more fitting proposed for crossing the uniquely lyrical coastline and central water body we call the Waitematā.
• Garth Falconer is an urban designer, director of Reset Urban Design and author of Living in Paradox:a history of urban design across kaianga, towns and cities in New Zealand.