The politics is hotly contested but what about the practicalities of tunneling not once, but potentially three times under Auckland's Waitemata harbour. The government's unveiled a mega project to future proof Auckland's Harbour Bridge, with plans for two underground vehicle tunnels stretching up to six kilometres from the CBD to Akoranga. There will also be a 21km light rail tunnel all the way to Albany. And reallocation of lanes on the existing bridge, with some dedicated exclusively to buses and cyclists and walkers. The staged construction is currently costed at $45 billion dollars. Nic Brooke is president of the Structural Engineering Society of New Zealand. [embed] https://players.brightcove.net/6093072280001/default_default/index.html?videoId=6332547312112