It’s been some time since we last heard anything official about the Additional Waitemata Harbour Crossing project but that all changed a few days ago with the NZTA updating the project page for it along with publishing two briefings on it to the Minister of Transport last year. More on them soon but first it’s worth noting they’ve now referring to the project as Additional Waitematā Harbour Connections and the narrative appears to be changing to one that moves away from a focus on route protection of a road crossing and more towards investigating whether it makes sense to build additional crossings of the Waitemata Harbour.

The first briefing is from February 2018 and has quite a traditional NZTA ‘road focused’ feel to it, seeking to push ahead on protecting the route with urgency. What is interesting from it though is that the plan now appears to be a tunnel from Esmonde Rd/Akoranga Station all the way to the Central Motorway Junction. This is to avoid having to do any more reclamation along the foreshore and would mean tunnels about 6km long, almost twice as long as previously planned. However, given the plans would see the existing bridge effectively become ramps only connected to Fanshawe and Cook streets, those from the western North Shore heading past the city would need to use the tunnel and this would likely mean first needing to head north on the motorway to Esmonde or Northcote roads and then doubling back to access the tunnel.

The second of the briefings is far more interesting and is likely responsible for the change in tone of the project. It confirms, with a lot of data, what we have suspected for a long time – that another road crossing is a complete waste of money that either undermines the goals for the city centre or doesn’t actually achieve much. I suspect this is related to the change in purpose noted earlier.

The briefing starts with some of the background information, including historic demands. The graph below is perhaps the most interesting of these, showing what’s happened in car and public transport trips over the past few decades:

It confirms that over a third (11,000) of the 31,000 people travelling over the harbour bridge in the morning peak are doing so on a bus and increased bus use accounts all of the growth in travel over the bridge during the AM peak since the early 1990s. This also confirms that it’s the approaches to the bridge that are the constraint, not the bridge itself. The paper goes on to highlight that of the 31,000 people crossing the bridge in the morning peak, 14,000 are heading to the city centre while the other 17,000 are heading past it. Delving deeper, of the 14,000 to the city, around 6,000 (42%) are travelling by car with 8,000 (58%) on buses. The other 3,000 on public transport were likely travelling via Ponsonby Rd or on a bus that passed through the city, say to Newmarket (these numbers will be from before the new network launched).

The key part of the briefing are the results of some really interesting transport modelling on a variety of crossing options. The modelling seeks to help answer the following questions

What if you don’t do anything?

What if you just built a light-rail crossing?

What if you build both a light-rail and road crossing?

What impact does introducing road pricing have on all these options?

What impact does widening (or not widening) the northern motorway from Esmonde Road to Constellation Drive have on all these options? It is noted in the briefing that widening the motorway would almost certainly be required.

The graph below shows the current numbers and how they are expected to change over time under the possible different scenarios.

There’s a lot going on in the graph above, but some of the key take-outs for me are:

Even if you introduce road pricing, building a road crossing still induces around 6,000-8,000 more morning peak car trips.

If you don’t do road pricing, build a road crossing induces around 10,000-15,000 more morning peak car trips

Light-rail seems to add around 3,000 morning peak PT trips. This seems quite low and reflects how transport models continue to struggle to simulate public transport capacity issues. It simply isn’t practical that we could more than double the number of buses in the “do nothing” scenario given the constraints on our city streets and that adding that many buses wouldn’t also impact on capacity on the bridge for cars. The NZTA acknowledge this fact in the briefing.

Building a road crossing doesn’t seem to reduce light-rail ridership.

A future with pricing and light-rail gives the highest “mode share” for public transport – with over half of morning peak trips being made by PT. Even without pricing and a light-rail only crossing you just get over half of trips being made via PT.

The next graph is perhaps the most telling of all, as it compares travel speeds and total vehicle kilometres travelled (VKT) of the different options:

Once again there’s a lot going on here, but let’s focus on the “with pricing” options – given that by the mid-2040s it’s pretty much certain we will have some form of road pricing in place (as a replacement for fuel taxes, if not for anything else). The other thing to remember here is that these vehicle speeds and VKT are across the whole Auckland region, meaning that what looks like relatively small differences between the options are actually likely to be quite noticeable.

Of the four scenarios, the best-performing in terms of average speed across the transport network seems to be the “road pricing and light-rail only” option.

This is closely followed by the “do everything option”

The third best scenario has a road crossing, light-rail and pricing but no widening north of Esmonde Rd

Thinking about this further, I came to the realisation that this is actually a pretty amazing finding – when you compare the first green bar and the third/fourth green bar. Comparing these highlights that basically the roading project does nothing over and above light-rail and road pricing. Those billions of dollars of spend on a massive new motorway tunnel and gigantic widening don’t even speed up traffic at all. In fact it seems that traffic goes slightly slower with the project in place than it does without it. This is not just a project that would have a cost-benefit ratio that struggles to reach 1 (i.e. does it generate enough benefit to justify the investment in it) but rather a cost-benefit ratio that would struggle to reach 0 (does it create any benefit at all?). This is also a point made by the NZTA

The next graph looks at impacts on the city centre, which highlight once again what a disastrous project the road crossing would be:

Looking first at a situation where there is road pricing, the road crossing induces around 3,500 extra car trips into the city at peak times. Without pricing the result is even worse, with the road crossing inducing 3,000-5,000 more peak car trips into the city centre. Not only is there probably nowhere for these cars to go in the city centre, anything that increases car volumes is completely contradictory to what the Council (and I’m guessing the Government) are trying to achieve.

Overall I think this briefing should put the final nail in the coffin of a road crossing of any form. For a long time we have been saying the crossing is too expensive, will create horrible environmental impacts, will ruin the city centre and won’t even fix congestion, and that we should build a light rail only bridge. The fact that including a road crossing actually makes car travel around all of Auckland slower than a “light-rail only plus road pricing” scenario is just staggering. This project will literally makes things worse for the very people it’s aimed at helping. The current investigation is due to be reported back in the middle of the year, it will be very interesting to see the results of this work.

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