As regular readers will know, we’re not exactly big fans of another road-based harbour crossing being a priority. We believe that after Skypath, the next crossing should be a rapid-transit-only crossing, providing those travelling to and from the North Shore with a complete and attractive alternative to the current bridge. It could be designed to leave space so that a future road crossing could be built if still needed.
Instead, the current most likely outcome is that we’ll spend $4-6 billion on a tunnel and massive interchanges at each end. And yet, because of changes they’ll make to how the existing bridge is used, it’s likely the extra crossing won’t even provide any additional capacity to the road network. About the best we’ll get is some bus lanes – AT and the NZTA have been suggesting that light rail could possibly go over the existing bridge, but my understanding based on conversations with various staff is that this is unlikely to be a realistic option.
So if we’re going to build a road crossing that doesn’t actually do much, perhaps it’s time to reconsider a cheaper bridge option. According to the last study by NZTA in 2010, a bridge option would be around $1.4 billion cheaper. That level of saving is nothing to be sneezed at, after all the entire cost of the Waterview tunnels project is $1.4 billion!
A bridge would also be considerably cheaper to operate and maintain – about $4m per year vs $20m per year (in 2010 $). Again $16m a year, every year, is significant. That’s roughly how much public subsidy is paid each year to top up fare revenue on the North Shore bus network.
The main reason for selecting a tunnel rather than a bridge was the result of public feedback around 5 years ago on the council’s Auckland Plan, and I’d say most of that feedback took place without considering the huge cost impact of their decision. One of the main reasons for this is the view it would obviously represent a dramatic visual change, which many people would be fearful of.
But would a bridge option be all that bad? Bridges all over the world can be some of the most stunning and iconic features of cities. Designed well they are more than just function.
Below are some of the renders from the NZTA study, so take a look for yourself. We were reminded of these when leafing through some of the obscure old reports so I wonder if most people even knew this was an option?
We quite like the design, the triangular cable towers are vaguely reminiscent of volcanic cones or perhaps sails on the harbour. In any case they have a monumental look. Cable stayed bridges are quite popular these days, as they are strong, stable and self-supporting during construction, which makes them fast and cheap to build. Of course there would be other types of bridges that could work: a grand suspension bridge like the famous Golden Gate, another steel arch bridge, a very simple concrete girder or maybe something wild and unusual.
Thinking about this, we think there are some other potential benefits of a second bridge, beyond the big construction cost saving and the cheaper operations and maintenance over time.
Firstly, it would be easy to provide road and rail on the same bridge, something that is difficult and expensive to do in a tunnel. We know that Auckland Transport are currently looking at rapid transit options to the North Shore. Given they are considering light rail across the isthmus and the airport, it wouldn’t be a stretch to imagine that they would consider it here too? And why not, light rail only takes up as much room as a traffic lane each way, and it can handle almost any grade you would want on a motorway bridge. So for the minimal cost of adding two lanes for light rail to the six lanes of motorway you could literally double the people carrying capacity of the crossing. It would also tie in nicely with the current plans for the isthmus which would see light rail along Fanshawe St to Wynyard.
There is also the possibility that you don’t need to add much at all. The NZTA designs below show a box section holding up the road deck. With a little tweaking to the design it could probably be big enough to run a rail line through each way. A rail deck inside the bridge structure is pretty common in bridges around the world, perhaps a double deck bridge is an efficient solution for Auckland?
Secondly, a new bridge would give a nice and more direct walking and cycling link, as we can see in the picture below. While we agree the Skypath is an excellent value retrofit and should proceed asap, having separate walking and cycling links on a more direct alignment would be even better in the long term. We would obviously expect walking and cycling connections to be a little wider than shown in the image below though.
Thirdly, bridges avoid a lot of the problems that tunnels can have with things like vehicle fires, water leaks and dangerous goods spills. Melbourne has had a pair of under-river tunnels since the early 2000s and it has experienced all three kinds of incidents, with many lives lost in one bad fire down in the tunnel.
So, could a relatively cheap and efficient new bridge with a mix of traffic lanes, light rail, walking and cycling be the right answer for the North Shore? Such a crossing might come in under $3 billion, less than half some of the recent estimates for doing motorway and rail in tunnels. But there might be some further savings to be had too. In the renders below we can see that the bridge itself is a fairly slender and graceful structure. But the real impact, and much of the cost, of the harbour crossing plans come from the connections either side, including what amounts to a new Spaghetti Junction in St Mary’s Bay complete with three additional tunnels under Victoria Park and a similar tangle of ramps and reclamation at Northcote Point though to Akoranga.
If the crazy plan to dump six lanes of bridge traffic onto Cook St was dropped, they could drop the duplicate Victoria Park tunnel and a mess of associated ramps and structures approaching it. The existing Victoria Park tunnel could be reconfigured into one lane each way to Cook St by adding a central fire wall, instead of building a second one next to it to get three lanes each way to the middle of town. This would improve connectivity to midtown while providing a reasonable, rather than insane, amount of vehicular capacity. Not only would this save the city from drowning in traffic that has nowhere to go from Cook St, it would also save a further half billion or so from the cost and reduce the amount of structures and reclamation on the waterfront.
A second advantage of new bridge with light rail would be the ability to drop the proposed busway additions on the old bridge. That sounds crazy coming from this blog, but you have to ask why you would need both a busway and railway next to each other when rail alone can do the job well. If you dig through the plans you can see NZTA have designed an elaborate series of busway lanes and flyovers either side of the harbour bridge, in addition to the rail designation (clearly they didn’t put much faith in rail ever actually happening). Dropping the busway links in favour of light rail only would likewise cut out a lot of concrete, and hundreds of millions of costs.
There are some further benefits of value engineering out the spurious ramps and links. With less linkages you need to reclaim less harbour and build fewer flyovers, but you’d also get to detune some of the worst bits we already have. Do the crossing right and St Marys Bay could be turned from eleven lanes of motorway into a six lane waterfront boulevard through to Fanshawe St and Cook St. It might have more in common with Tamaki Drive than Spaghetti Junction.
So what about it Auckland? Would we be happy with a new bridge if it meant traffic, rail and people could be accommodated together while saving billions of dollars and reducing the impacts on the waterfront areas? Is there a “lean and mean” road solution that could be funded and built earlier while also giving people the rapid transit crossing they want?
To finish we just have to ask, why was this option dropped so readily? Given the potential to save billions and get better outcomes shouldn’t we at least have a thorough discussion?