I slightly jumped the gun with yesterday’s post about the launch of the ANZAC Centenary Bridge website – as it’s only live today. There’s quite a bit of information on the site, including a number of images – and also a feasibility study. Here are a few of the images from the site:
This image looks from around Little Shoal Bay towards the CBD. I must say I’m not a huge fan of that proposed design (which is based on the Erasmus Bridge in Rotterdam) as it comes across a bit, well, unbalanced. I would much prefer, if we were to go mad and build this bridge, to follow a design more similar to the bridge’s potential namesake in Sydney.
This is perhaps the most interesting image/map. It shows that the proposed alignment would cut through Tank Farm (although seemingly as a tunnel, if that’s what the dotted line means), before travelling along a rather longer bridge span, and eventually linking up with the current motorway around the Onewa Road interchange. All the area highlighted in orange is currently used for motorway purposes and could (theoretically at least) be redeveloped to help fund the bridge project.
Perhaps the most interesting thing on the website is the feasibility study. There are a couple of things mentioned in that feasibility study that I just have to make comment on, because they’re completely and utterly wrong. The first is this claim:
Traffic flows across the Auckland Harbour Bridge have increased rapidly in recent years, and are predicted to increase still more rapidly in the future. The annual average daily traffic figure for the Bridge has risen by around 30 percent in the last 20 years (from 125,000 to 165,000). The figure is expected to rise by another 40 percent by 2025, with passenger transport figures increasing disproportionately quickly.
Now according to NZTA traffic count data, we can see the trends in traffic flows over the harbour bridge during the past few years. The data is:
2004 – 161,990 vehicles per day
2005 – 166,126 vehicles per day
2006 – 168,754 vehicles per day
2007 – 165,747 vehicles per day
2008 – 154,925 vehicles per day
Hmmmm…. yeah well I would hardly call that a “rapid increase in recent years”. And with traffic levels having trended downwards over the past two years I would be pretty hesitant to expect them to increase particularly dramatically in the future.
The other thing that the feasibility study gets completely wrong is the long-term future of the current bridge:
As mentioned above, a key argument made against a stand-alone bridge option is that it would limit network resilience. However, the tunnel option would only provide additional network resilience for as long as the existing bridge remained operational – i.e., for another 30-40 years. In the longer term, therefore, the net gain in network resilience would be zero, and inadequate carrying capacity would mean yet another harbour crossing would be required.
Furthermore, with a new bridge it would be possible to future proof against most of the factors that are likely to cause a threat to network connectivity. Issues such as physical impact from ships and other watercraft, wind damage, and seismic activity could be adequately and appropriately addressed in the design of a new bridge, through briefing on and achievement of international best practices. In general, bridges are at less risk than tunnels of being closed to traffic as a result of vehicle accidents, fire, flooding, failure of mechanical systems, and acts of malevolence.
Now that is complete rubbish. It is only the clip-ons of the current bridge which have a limited lifespan. NZTA have clearly stated in the past that the main span of the bridge, with a proper level of maintenance, will be able to be used for potentially centuries to come in the future. Furthermore, the clip-ons can theoretically be replaced, it’s just a matter of finding a way to manage traffic flows whilst replacing them (a rail tunnel would come in handy there!)
I think the “network resilience” argument is the one that will kill off this “replacement bridge” idea. One of the main reasons for doing another harbour crossing would be improved network resilience – so why on earth would you spend around $2.5-3 billion to not actually achieve that goal?