Public transport and congestion in Wellington

Last week, I took a look at some new research from the Netherlands that estimated the benefits of public transport for car travel times based on data from 13 “natural experiments” – public transport strikes. The Dutch researchers found that PT provided significant congestion reduction benefits – around €95 million per annum, equal to 47% of PT fare subsidies.

While the data was specific to Rotterdam, I’d expect to find similar results in most other cities with half-decent public transport networks. The whole thing got me wondering: Is there any similar evidence from New Zealand?

Fortunately for PT users and drivers, but unfortunately for researchers, potential PT strikes have mostly been averted over the last few years. However, Wellington did experience a “natural experiment” of sorts back in June 2013, when a major storm washed out the Hutt Valley railway line:

Source: NZTA

Source: NZTA

The Hutt Valley rail line was out for six days, including four working days. During that period, things got pretty ugly on the roads, as the motorway into downtown Wellington didn’t have enough capacity to accommodate people who ordinarily commuted in by train.

The Ministry of Transport (among others) very cleverly observed that this was a great opportunity to learn something about the impact of PT networks on road congestion. During the rail outage, they surveyed around 1,000 Wellington commuters about their travel experiences. According to their report, they found that:

  • The closure of the Hutt Valley rail line put significant pressure on the road network. Delays for commuters were most severe on the Monday following the storm. Traffic on State Highway 2 was severely congested, with morning peak hour conditions lasting two hours longer than usual
    • 80 percent of Wellington commuters from the Hutt Valley and Wairarapa experienced a longer than usual trip
    • 32 percent of them experienced delays of over an hour
  • the severity of commuter delays lessened over the week, with the number of commuters from the Hutt Valley and Wairarapa experiencing delays of over an hour halving by Wednesday 26 June

Essentially, what happened was that a bunch of people who ordinarily caught the train from the Hutt Valley couldn’t do that due to the storm damage. A quick eyeballing of MoT’s graph of daily rail patronage suggests that around 4,000 people had to make other travel arrangements:

Wellington storm daily train patronage

Almost half of the rail commuters from the Hutt Valley opted to drive instead, while the remainder chose to take replacement buses or to stay at home instead. This had a serious impact on motorway traffic, as shown on this graph of hourly southbound traffic volumes. On a normal day (the green or blue lines), traffic volumes peak at around 7-8am, and fall off sharply after that.

By contrast, on Monday 24 June, when the rail line was out, people were still travelling in (slowly) until almost 11am. That’s some serious congestion:

Wellington storm hourly vehicle flows

Based on survey data, MoT estimated that the storm damage increased average travel times during the morning peak by 0.329 hours (20 minutes) on Friday 21 June, 0.309 hours (18.5 minutes) on Monday 24 June, and 0.230 hours (14 minutes) on Wednesday 26 June. It then used those estimates of average delay for people travelling at peak time to estimate the added cost of congestion that arose as a result of the Hutt Valley rail line outage:

Wellington storm cost of increased travel time

In short, a four-day breakdown in part of Wellington’s public transport network cost morning peak travellers around $2.66 million in lost time. If we assume that there was a similar level of delay during the afternoon peak, when people are commuting out of downtown Wellington, the total cost would be roughly double that – $5.32 million.

This can give us a rough estimate of the value of public transport for congestion relief in Wellington. Extrapolated out over a full year (i.e. 250 working days), these results suggest that the Hutt Valley rail line saves drivers the equivalent of around $330 million in travel time (i.e. $5.32m / 4 days * 250 working days).

That is a very large number. According to an Auckland Transport report comparing Auckland and Wellington rail performance, Wellington’s overall rail network only cost $81.2 million to operate in 2013. 56% of operating costs were covered by fares, meaning that the total public subsidy for the network is around $36 million per annum.

On the back of these figures, it looks like Wellington’s drivers are getting a fantastic return from using some fuel taxes to pay for PT rather than more roads. The travel time savings associated with the Hutt Valley line alone are nine times as large as the operating subsidy for the entire Wellington rail network.

There are two caveats worth applying to these figures, one practical and one methodological.

First, it’s likely that the value of rail for congestion relief is unusually high in Wellington due to the shape of the city. Here’s a map of Wellington’s population density and infrastructure in 2001 and 2013 (from my analysis of urban population density). Dormitory suburbs extend linearly up the Hutt Valley and towards Porirua and the Kapiti Coast. Everyone travelling from those places to downtown Wellington are funnelled through a single transport corridor running along the shoreline of the harbour:

Wellington density 01-13 v2

In Wellington, losing the rail line means pushing everyone onto a single road. (Unlike Rotterdam, cycling isn’t especially viable due to the lack of safe infrastructure on this route.) In other cities, there tend to be a greater range of alternative routes, which spreads around the traffic impacts.

Second, these results aren’t as robust as the Rotterdam study, due to their use of survey data rather than quantitative measures of traffic flow and speed. They’re not likely to be totally wrong, but it’s likely that people over- or under-estimated commute times, or that the survey wasn’t representative of all travellers (which could invalidate MoT’s extrapolation to all morning peak travellers).

However, the increasing availability of real-time data on traffic speeds from GPS devices means that the next time this happens, it will be possible to measure the impacts in much greater detail and with greater precision. The Rotterdam study offers some good methodological insight into how best to do that – it looks at transport outcomes at specific locations over a long period of time, and controls for seasonal and weekday effects that may influence transport outcomes.

Lastly, it would be really interesting to see some similar analysis done for Auckland. I’m sure that there have been a number of full or partial rail network outages, either due to bad weather or scheduled track upgrades. Perhaps it would be worth taking a look at congestion on those days.

Rail costs in Auckland and Wellington

Is Auckland getting ripped off when it comes to the cost of running rail services? Councillor Mike Lee has long thought so and has frequently raised the issue by way of comparing the costs of running the Auckland and Wellington rail networks – $125.6 million vs $85 million in the financial year to 30 June 2014. At that time rail patronage was also almost identical in each region. He has frequently blamed the way rail is set up saying:

A contributing factor may lay in the fact that in Wellington services are a matter between the Wellington Regional Council and KiwiRail. In contrast the Super City’s rail services management system is a complex, unwieldy ‘too many cooks’ arrangement of Transdev, KiwiRail, and of course Auckland Transport (AT) – which is demonstrably too expensive, inefficient, and allows too much room for dodging accountability.

Auckland Transport have looked at the differences in the past and come to the conclusion that the differences will largely iron out once electrification is finished however I don’t think Mike has ever been happy with that – and he seems to have an intense distrust of AT and Transdev in particular.

The Council’s Finance Committee tomorrow are presented with the outcome of that review which has found that when you account for the differences in the volume and nature of services provided, the costs aren’t all that different. Further it needs to be remembered that for FY14 Auckland had only had electric trains running on the Onehunga line for a few months. As such the efficiency of the Auckland network is only expected to improve – especially when combined with the growth in patronage expected. Here is what he found:

As mentioned above the costs in Auckland are much higher. The biggest single difference comes from labour costs – more on this soon – and train maintenance. The latter should have been reduced substantially with the arrival of the electrics.

Auckland vs Wellington Cost comparison Costs

So what causes the costs to be so much higher in Auckland. One major aspect is that there are considerable differences in both how many and how services are run. The report notes that in Auckland services are run stopping at all stations along the way. By comparison Wellington runs multiple short and long run service patterns on most of it’s lines. Boiling down the results they’ve been measured on the basis of how many full line services they equates to. Using that measure Auckland ran 2210 services per day while Wellington ran 1778. This highlights that one of the main reasons for the difference in cost is simply a difference in service provision.

Another factor identified was the level of dead running. Basically if services in Wellington terminate somewhere they can immediately go to a stabling yard nearby. In Auckland they often have a lot of travel some distance to get back to a stabling yard and all those trips add up to over 200,000 km per year. I suspect some of this has already been improved through the use of the newish stabling yard at the old railway station.

Auckland vs Wellington Cost comparison Dead Running

All up when adjusting for all of these factors the report says that the Auckland network is only approximately 7% more per hour to operate and that’s before taking into account the impact electrification will have.

On the other side of the ledger is the revenue from passengers. The report notes that the fare structures are fairly similar between the two cities however the average fares are quite different at $2.65 for Auckland vs $3.72 for Wellington. The main reason for the difference is that trips in Auckland are generally shorter. It had almost 1 million trips (9%) that were one or two stages while in Wellington the main lines of Kapiti and Hutt Valley most trips are a minimum of three stages due to the local geography and design of the system.

Overall it suggests that rail in Auckland isn’t as bad as the headlines often suggested which is good news

Auckland vs Wellington Cost comparison Recomendations

I’m sure this is a topic that will come up again and now the electrics are rolled out then for the future we should finally have more accurate figures to work with. One thing we do already know is that the subsidies are coming down with the subsidy per passenger km coming down.

2015-07 - Subsidy per PAX km

Congestion Charging in Wellington

Auckland may be the most prominent voice when it comes to discussing congestion charging in New Zealand but it appears other cities are keen to join in. Last week it emerged that Wellington are also wanting to look at congestion charging however unlike Auckland where it is being talked about primarily as another revenue source, Wellington say they need it to deal with the after effects of building new motorways.

The call for a toll on Wellington’s CBD is growing louder, with studies revealing the central city could be flooded with almost 12,000 more cars once its proposed new motorways are up and running.

Wellington recently joined forces with Auckland to lobby the Government for the law changes necessary to introduce user-pays charges as a means of reducing car use.

Some of the ideas being floated include a congestion charge, such as the one used in central London, and fees that ramp up the cost of long-stay commuter parking.

While Auckland’s chronic traffic congestion is already apparent, Wellington’s is expected to get worse once the Kapiti expressway, Transmission Gully motorway, and Petone-Grenada highway are all built, making journeys in and out of the capital by road significantly easier.

Recent studies by Greater Wellington Regional Council show that, even with continuing investment in public transport, there are expected to be 11,500 more cars entering Wellington during the morning rush in 2031.

This has prompted the council to also model how that scenario would change, with various user-pays charges in place, despite some of them currently being beyond the law.

It found a congestion charge would have by far the greatest impact on car use in 2031. Vehicles trips in and out of Wellington’s CBD would drop by about four million annually, while public transport trips would increase by the same amount.

Tolling the yet-to-be-built Transmission Gully motorway and Petone-Grenada highway, which is currently legal, would have a more “moderate” impact on car use, as would a levy on all-day parking, which is not currently legal.

A couple of thoughts immediately spring to mind.

  • So far from the RoNS addressing congestion as the government/road builders/lobbyists so often love to claim, they’ll actually be making it worse by encouraging more people to drive, some of which comes from people encouraging people off using public transport and into their cars – making both systems less efficient. Why then are we wasting well over $2 billion on the new Wellington RoNS which already had poor economic outcomes.
  • From memory the NZTA have already ruled out tolling Transmission Gully as their modelling suggested that very few would use it if they did so. My guess is that would rule out any individual road specific tolls.
  • Like Auckland it appears that Wellington is blighted by politicians who seem to have the attitude of not caring what gets built as long as the government are spending money in their neck of the woods. There also seems to be the general attitude that public transport is only viable a mode of last resort.

The last point is displayed very well at the start of this interview on Radio NZ with Paul Swain, the chairman of the Regional Transport Committee who seemed aghast at the slight possibility of not building some new roads. It is also appears to be the attitude that is taken by Wellington City Councillor Andy Foster later in the piece who appeared quite annoyed that the Basin Reserve Flyover was cancelled – and as per this excellent op-ed from Dave Armstrong it appears both were quite keen on it.

Or listen here

I also found Foster’s comments on public transport interesting. He’s obviously correct that Wellington has the highest use of public transport in the country however I’m not sure I would go as far as him in saying that Wellington has a good system. There certainly seems to be a lot more that could be done to make the system better and therefore increase patronage. Many of those are things that Auckland has done or are on the agenda such as integrated ticketing and fares and a better bus network and greater bus priority. I kind of get the feeling that Wellington won’t really wake up and realise how far behind it’s falling until in a few years (at current rates) when Auckland passes them.

Coming back to congestion charging, I was also amused by this press release yesterday by the Property Council which claims that reducing cars in to Wellington would have catastrophic effects.

Wellington Branch president Mike Cole says slowing down traffic flow into the centre of a city of only 191,000 and a region of 471,000 people is ridiculous.

“They are talking about methods used in central London; a city of 8.6 million people. London could use the drop in traffic-flow, while we are desperate to get our city centre thriving by getting more people in.

“I think the Council is totally oblivious to the catastrophic effect this would have on retail and employment. Why would we drive people away, when we are working so hard to get them in?”

Perhaps someone needs to tell them that it’s people that buy stuff, not cars. Flooding the CBD with cars will only make it a less attractive place for people to be and therefore they will be less inclined to work and shop there.

Who knows what the outcome will be on congestion charging in either Auckland or Wellington but it’s certainly interesting that both cities are now starting to talk about it much more openly. As has long been the case my personal position is that any form of congestion charging should be designed at least initially to be revenue neutral – substituting rates or fuel taxes. That would give the public a greater level of comfort that it isn’t just a revenue gathering exercise but rather a traffic demand tool. I also think it is something that should be implemented in advance of another wave of road building so we can see the real impact it has before committing billions to construction.

Basin Bridge Bowled again

Fantastic news out of Wellington yesterday with the High Court rejecting completely the NZTA’s appeal of the decision by the Board of Inquiry to decline consent for the Basin Reserve Flyover

Basin Bridge Image 2

The High Court today dismissed the NZ Transport Agency’s attempt to overturn the rejection of its controversial plan to build a 300-metre concrete flyover alongside the Basin Reserve.

In a decision released this afternoon, the Court stated:

The Transport Agency has not established that in its decision the Board of Inquiry made any error of law … Consequently the Agency’s appeal is dismissed.

And earlier:

The Board’s decision does not contain any of the errors of law alleged.

The Transport Agency had appealed against the Board of Inquiry’s decision to decline consent for the $90m flyover alongside the Basin Reserve.

The Government set up the Board of Inquiry process as a way of fast tracking consents for large projects to stop them being held up in years and years of appeals. The only appeals were allowed on points of law.

Some of the key reasons consent was declined in the first place was

  • That while the project would improve the cities transport system that it would do so at the expense of heritage, landscape, visual amenity, open space and overall amenity.
  • They are uncertain how the plan would have actually accommodated for Bus Rapid Transit as proposed in the Spine Study.
  • That the quantum of transport benefits were substantially less than what the NZTA originally said in lodging the NoR as they included transport benefits from other projects.
  • That while North/South buses would be sped up, that the modelling doesn’t show any impact effect of this on modal change.
  • That while there are some improvements for cyclists it’s mostly in the form of shared paths which will introduce potential conflicts between pedestrians and cyclists.
  • That the dominance of the bridge would cause severe adverse affects on the local area and the mitigation measures proposed would do little to reduce that. They also found the new building proposed for the Basin Reserve would exacerbate this.

Some of these are likely to have massive implications for other projects such as the Additional Waitemata Harbour Crossing and the Reeves Rd Flyover. For example it likely means that the NZTA are going to have include not just the tunnel and direct connections in their consent for AWHC but also all the associated road widening of the Northern Motorway and Central Motorway Junction – which we understand is substantial. It could also stop the idea of building a combined road and rail tunnel across the harbour as the NZTA would have to consent the connections on either side. This will likely be why they’ve told us that they will not be including rail in current consent process.

AWHC - Indstry Briefing


Coming back to Wellington it will be interesting to see how the NZTA respond. It’s time they gave up idea and started thinking about other solutions.

Waiting a century for a cycleway

The Wellington to Hutt Road is, and has been for a quite long time, one of the most popular and important cycle routes in New Zealand’s urban areas. It connects a busy downtown area with large suburban areas in the Hutt Valley, via a scenic harbour front. It’s also a rare flat route in a hilly city where cycling is relatively popular by New Zealand standards.

Given this, you’d expect there to be a safe, separated cycleway of adequate width squeezed somewhere in between the road and rail line. Unfortunately, you would be wrong.

If you’re headed northbound from Wellington to the Hutt Valley, you are required to squeeze into a narrow strip between two lanes of traffic and a vertiginous hillside. Some green paint has been provided along some parts of the route, as shown in the Google Street View:

Wellington to Petone cycleway 3

I haven’t cycled this route, but if I was headed this way by bike I’d probably take the train to Melling and cycle north from there. It just doesn’t feel safe.

The southbound route seems a bit better, as a narrow strip of tarmac has been fenced off between the motorway and the rail tracks. This is helpful for people cycling to Wellington, but I’ve heard that it sometimes causes dangerous confusion for northbound cyclists who get on the separated path in Wellington and then find themselves tipped out against oncoming motorway traffic near Petone:

Wellington to Petone cycleway 2


Unfortunately, the Wellington to Hutt Road has been disappointing people on bikes for a very long time. The Kennett Brothers fantastic book Ride: The Story of Cycling in New Zealand provides some background. Over a century ago, when cycling was a main mode of transport for many urban New Zealanders, there were Parliamentary debates over what should be done to improve the road for cycling, and working bees to remove sharp objects from the preexisting gravel cycle path. However, nothing much got done:

“When roads were improved for motorists, it was not always agreed that the cyclist should share them. Around the time of the First World War, some of the main Hutt Valley roads were bitumen sealed, but a by-law was passed forbidding cyclists from riding on them. On the main Hutt-Wellington route, cyclists and horses were forced to share a metalled path strewn with sharp objects from the nearby railway line. In one novel attempt to clean it up, a nail finding competition was won by a boy who bagged 391 of the total 1843 nails found on the path.”

The Kennetts dug up this old picture of the Wellington to Hutt cycleway in 1978, after almost a century of neglect:

Hutt Road bicycle path in 1978

The route is better today – the northbound cycle path is at least paved – but as the Google Street View shows, it’s still a far cry from a safe separated cycleway. The good news is that the NZTA’s new Urban Cycleways Programme looks like it will finally upgrade the route to an adequate standard.

One of the key projects in Wellington is the “Melling to CBD” cycleway, which seems to include an upgrade of the areas I’ve highlighted above:


I haven’t seen any detailed designs for the project yet, but the NZTA states that:

This project will provide a high quality cycleway between Melling and Wellington’s CBD, significantly improving the level of service for both cyclists and pedestrians. It will offer a safer and more attractive route for journeys between home and work or educational institutions, and will pay particular attention to how cyclists travel through intersections.

These additional facilities are expected to encourage new, less confident people to cycle as well as catering to the high numbers of people who use this route already.

Hopefully, this project will finally fix the longstanding issues with cycling on this road. The city has waited over a century for a safe cycling route between Wellington and the Hutt Valley – it would be a shame to prolong the wait any longer.

Lastly, I’m sure that many other roads in New Zealand have long-standing challenges for safe cycling. What other issues have you noticed, and how long have you been waiting for a solution?

When is Bus Rapid Transit not Bus Rapid Transit?

This is a guest post from Andy C – a long time Wellington public transport user…

Well when it is Wellington of course…

Some of you may remember that back in 2013, the Wellington City Council undertook its ‘public transport spine’ study, which looked at options for the highly used public transport spine from the Wellington railway station to the Hospital in Newtown. The problem definition from the study was quite clear:

  • In future years, too many vehicles and modes will share a constrained corridor resulting in longer and unreliable transport journey times which will worsen over time
  • There will be increased traffic congestion in the strategic and local road network and additional environmental impacts as a result of less mode share for public transport.

Furthermore, the report noted that there is a clear problem with the current public transport network: “It is difficult to increase PT patronage and mode share under the current circumstances. Buses are not segregated from general traffic. Wellington’s bus services are perceived by the public as being less attractive and less reliable than private vehicle journeys.”

Therefore the study looked at three options to solve or reduce these problems; bus priority, bus rapid transit (BRT) and light rail.

Wellington BRT route

As you all know, Wellington is a city defined by its geography. Lots of hills, with traffic funneled through a small number of key routes (either in the valleys, or along the hill tops). If you are traveling from the south (Island Bay), you have to either go past the Basin Reserve, or through Mt Cook, just a few hundred metres away. The same is true for traveling from the east of the city (Kilbirnie, Miramar etc); you either go past the Basin Reserve or around the bays. If you’re coming from the north (hill suburbs and the Hutt) you’re actually lucky in having the option of trains, buses and the motorway, while the west (Karori) is probably the most challenging with only one major route in or out.

To my mind, this actually gives us good options for some sort of dedicated public transport spine, because so many of these routes have been identified by the local Council as being high on the list for intensification of housing and public amenities. Therefore with good planning, we could see increased public transport use simply from all the new people living along the high use routes.

After lots of debate, the result of the spine study was that BRT (defined as ‘dedicated bus lanes for new high capacity vehicles’) had the highest benefit to cost ratio and thus would be investigated further. The initial spine would run from the railway station to the hospital and Kilbirnie.

Well on Friday 31 July the Wellington City Council released its indicative business case for BRT (you can read it here), based on a report written by PWC. And sadly for users of public transport in Wellington, the key recommendation looks nothing like a BRT.

The indicative business case finds that actually, it would be too expensive to even think about BRT as defined above. Instead it provides two simpler options; bus lanes in targeted locations, with limited intersection priority with a Benefit Cost Ratio of 2.3, or bus lanes along the whole route 24/7, with full intersection priority with a Benefit Cost Ratio of 1.5.

Now call me a cynic, but neither of those things sound like ‘dedicated bus lanes for new high capacity vehicles’, although the Mayor insists on calling it that in the Council press release which you can read here. And what is even worse, the document notes that both options are predicated on there being ‘a grade separated Basin Reserve’ (which will have to be a topic of a future post).

A couple of days ago the local paper the Dominion Post even got in on the cynical act, which is something of a surprise, with a scathing editorial about current public transport plans that included this summary:

Recall that Wellington mayor Celia Wade-Brown came to office pushing a light rail system, only to see it lose out to the souped-up bus plan. That was supposed to see “high capacity and high quality buses running on dedicated bus lanes with priority at signals”.

But consultants in a new report blanch at the cost of doing that properly and recommend two watered-down alternatives. The cheaper one offers “bus lanes in targeted locations” with “limited priority” at intersections. Bus passengers can be forgiven for asking how that differs from the status quo.

Well I have to say, that after all the studies and recommendations over the years, if all we need to improve public transport along this route in Wellington is a few painted bus lanes (and enforcement of them please!) and some reprogrammed traffic signals, then let’s get it started tomorrow.

But in the meantime, please don’t call either of these preferred options Bus Rapid Transit. Because no matter how you look at them, they’re not. And what’s even worse, you’d be hard pressed to say they actually solve either of the problems identified back in 2013.

Development update: June 2015

It’s been a busy month for development: Auckland Council announced they’d be selling off some of their surplus land, and so did the government (which Matt wrote about here).

This makes good headlines for the council and government, making it look like they’re taking steps to tackle the supposed housing crisis. However, I’m not sure how much of the land is actually “new” to the scene – e.g. the council’s announcement includes the land being developed for the Flat Bush town centre, which has been a work in progress for many years, the government’s announcement includes Hobsonville and the McLennan subdivision in Papakura, and so on. Anyway, I’ll look at this more in the next few weeks, and see what needs to go into the RCG Development Tracker as a result.

Developments around New Zealand

Speaking of the Tracker, I haven’t written much about what’s happening in Wellington yet. Using the fantastical power of computers, let’s whisk you away to the nation’s capital, where you can see a number of projects in the city centre or nearby.

WGT development

Te Aro continues to transition to a more residential environment, and accommodation and mixed use projects are reshaping Wellington’s waterfront areas. A lot of the projects on this map are now coming to an end, and it’s not immediately clear what will replace them. Based on a recent visit, there certainly aren’t as many cranes visible in Wellington as there are in Auckland or Christchurch.

As for Auckland, there are a number of new things in the Tracker this month (including 1 Mills Lane, which could be the tallest office building in the city, as well as Mitre 10’s new head office building, the Oasis and SOMA apartments and more).

I was also down in Christchurch a couple of weeks ago, and it’s due an update as well – but that will have to wait until next month. In the meantime, you might enjoy looking at CERA’s Progress Map or the Avenues Four page.

Auckland Building Consents

Turning to building consents in Auckland, April was a massive month for apartments: 438 units were granted consent, with 392 of those in the Waitemata and Gulf Ward. This probably reflects two or three major projects getting the go ahead from Council (I’m guessing it might have been Park Residences and 88 Broadway, as the numbers more or less match up and both are now underway).

The graph below shows moving annual totals for these and other higher-density consents:

Apartment consents


In fact, when you stack these lines on top of each other and add in the consents for standalone houses, you can see that most of the growth in consents over the last two years or so has come from higher-density dwellings:

Auckland total consents

There’s a tendency in some circles to suggest that Auckland’s housing issues stem from a lack of land on the fringes. However, higher-density dwellings are going to play an important role in Auckland’s growth, and in housing the extra people who want to live here. Let’s hope they’re getting the attention they deserve from the council and government.

Funding the Basin Flyover Fight

Yesterday the Architectural Centre in Wellington have launched a fund raising campaign to fight NZTA’s continued waste of our money on expensive lawyers for their hopelessly unimaginative and retrogressively conceived Basin flyover project. Here’s the Give-A-Little site with a recap of the situation.

Basin Appeal



This is a Guest post by Wellington Architect Guy Marriage

Wellingtonians get a hard press in the Auckland papers sometimes, but last Thursday we thoroughly deserved it. We are normally a fairly resilient lot, and put up with more than our fair share of howling wind and torrential rain at times, but regularly battle through with trains and buses all performing admirably. Even our regular rush hour traffic jams only just live up to their name, and are normally well over within the hour. We know about Auckland’s horrific traffic, and sympathies, we really do. But last Thursday, we suffered a total melt-down, and for a supposedly heavily resilient city, that was a pretty big fall from grace. So what happened?


As you may have heard, broadcast all over the evening news, we had a bit of excess rain. About 8 times more rain in an hour than we get in a month, or some such unbelievably wet statistic like that. And then the big wet went on and on, and eventually we had some slips, where our glorious hills decided they didn’t want to be vertical any more, and so they poured out over the flat bits along the edge of the water. Unfortunately for Wellington, all of our escape routes out of the city run along the same flat stretch of road to the Hutt, and so a small slip on the Hutt Road blocked off a route north along State Highway 2, diverting all the SH2 traffic to SH1. Doubly unfortunate really, because on the other side of the hills, SH1 was also blocked off, and that meant they had to send all the traffic back to SH2, over SH58. There is only one other road, the Paekakariki Hill Road, which is narrow and windy, and is frequently blocked by slips anyway, so inevitably that blocked up too. No way in, no way out. The capital was blocked off from the rest of New Zealand. Did you miss us?


The road was therefore bumper to bumper traffic jam from Wellington all the way to Porirua, and also at a standstill over the hills back to the Hutt Valley on the other side. If you’re not from Wellington, then none of that will make sense, and the nearest I can give you as an example is if the Harbour Bridge was closed, and the NorthWestern motorway was closed as well, and all the traffic between Manukau and Auckland was diverted via Puhoi, and then all the cars stopped moving. Yes, exactly, a stuff-up in traffic terms of monumental proportions, one considerably worse than the average Friday night jam in Auckland, and we will inevitably face calls for yet more roads to be built, just in case this happens again.

NZTA WGTN flooding

But wait, there’s more. Surely none of those road closures matter, as Wellington is the most public-transport oriented city in the nation, is it not? Well, yes, but on Thursday even that let us down as well. Every single train to every single destination was cut, and the central Wellington Railway Station was closed down. That’s a station that normally is about 3 times busier than Britomart, and we have shiny new trains too for the most part. But that accursed rain had deluged rocks and washed out gravel over every set of tracks. Replacement buses normally suffice when there is a traffic setback, but with all the roads and all the rail out, there was no way that the few remaining charter buses could keep up with the demand. The city actually took the unheard of step of telling all commuters from out of town to stay in town, spend the night with friends, to rent a room or borrow a couch, and give up entirely on moving anywhere. I’m not sure if that has happened to any city in living memory before, outside of a war zone. Even when Hurricane Katrina hit New Orleans, or when Super-Storm Sandy hit New York, they were still able to move people in and out of the city. But not Wellington, not last week. The only methods of transport still working were the planes (if you wanted to fly to Auckland and drive back down to Upper Hutt) and the ferries, which gave you a choice of sailing through the storm to Picton, or in a much smaller ferry, riding the waves up to Petone beach. Except of course that Petone beach has a damaged pier, and one of the small East-West Ferry boats was out of action, so that left just one small catamaran sailing back and forth to Petone all evening. I was fully expecting my floor to be full of refugees from the storm, but it was, miraculously, fugee-free.


Wellington train_4740

Not that it really made the slightest bit of difference to Wellingtonians however. Within the city itself, there was a fair bit of wetness, more than usual, but nothing was broken. Everything still worked, everyone got home. Buses still ran, taxis still taxied, and cyclist continued to ride on their non-existent cycle network. We haven’t got a cycle network yet, because some pathetic councillors went feral, and have slowed everything down for reasons known only to themselves. We are, it seems, the only city in New Zealand with a pro-Green, fervently cycling Mayor, and yet we have not a single functioning separated cycle lane anywhere of any use on any major traffic route, which seems just a little bit odd. While the usual dips and hollows were fuller of water than usual, it seemed to me that the city performed admirably well, and lived up to its resilient reputation. You could have even thrown in a moderate earthquake or two, and the city would have shrugged them off as well, due to the steady stream of strengthening projects that have been going on. We’re a city that is like a brand new iPhone 6, already with a sturdy waterproof, shockproof rubber case on, and you could drop us from the upstairs balcony and we wouldn’t break, at least not completely. But we might bend a little if you sat on us.

But what this points to is that while Wellington City might be tough enough in parts, its the Regional Council and NZTA that were shown up as monumentally unprepared for disaster. I think we have just seen the biggest case for abolition of the Regional Council, right there. What if it had been a real, serious disaster, not just a few hours of torrential rain? The Civil Defence motto down here is “Get Through.” Clearly, that is not something that we yet can do.


NZTA have started work on the billion dollar highway known as Transmission Gully, an ironic name as they could only start work there when they had removed all the transmission lines, in case they fell over while they were digging out the gully road. One day, after an inevitable cost inflation to (probably) nearly two billion dollars, there will be a new road north, two lanes each way, all the way, and a new Petone to Granada link road – and you know what? If both of those roads had been built already, those other traffic snafu may well have happened just the same. The Petone to Grenada route will have to involve the moving / removal of some eight million cubic metres of rock, which wont be an easy task. The Transmission Gully route still relies on sending all the traffic along the waterfront and up the Ngauranga Gorge, both of which were heavily affected by last weeks rain, with several small slips/rockfalls and a lane taken out of action in the Gorge. Transmission Gully is also sitting firmly on an earthquake fault line and highly susceptible to slips as well, so there is a lot of work to be done securing hillsides before that route will ever be “safe”. We need NZTA to try a whole lot harder to battle-harden the existing network and we need Kiwirail and GWRC to make sure that public transport is a whole lot more resilient down here. 

What’s happening to Takapu Valley?

As Peter found when covering the Ministry of Transport’s review of capital spending on roads (parts 1, 2, 3, and 4) our multibillion dollar national transport budget is being spent in some bizarre ways. Money’s being allocated to major roading projects that don’t offer many economic benefits in return.

MoT state highway BCRs 2005-2012

While the high-level picture is clear, it’s not always obvious what’s going on in project selection. Why does the New Zealand Transport Agency (NZTA) choose one project over another? What are their processes for assessing “strategic fit” and other considerations?

Some smart people have been taking a critical look at a major Wellington road project that’s been flying under the radar: the Petone-to-Grenada motorway. Like the Transmission Gully motorway, it’s being touted less for its benefit-cost ratio than for its impacts on the “resilience” of the Wellington region.

Tamara Duran, who writes on the Takapu Valley website, provides a useful summary of the project… and the issues with the project. In addition to her extensive analysis of the the impacts of the project on resilience (parts 1, 2, and 3), she’s put together a primer on the project, complete with maps for the out-of-towners:

Since the Christchurch and Tōhoku earthquakes, “resilience” has been the mantra of… pretty much anyone building anything, be it a building, a corporate structure, or a communications network. We all want to be resilient, to survive whatever has just happened and get back up and about our normal business as quickly as possible.

The New Zealand Transport Agency has picked up on how keen everyone is on resilience, and so is now including it in all of their sales material. Perhaps unsurprisingly, NZTA has defined “resilience” from a transport perspective as “more roads”. Not “more transport options”, and not even really “better roads”, just more. Got congestion problems? Build another road to get around it. Got a road falling apart? Build another road to take traffic off it.

Case in point: The Petone to Grenada link road, in Wellington. This road has been in the investigation and planning stages for a good 20 years now, the reason being Wellington’s notoriously challenging geography. To get from the CBD to the rest of the Region (and ultimately the rest of the North Island), there are essentially two routes out – SH1 up Ngauranga Gorge, and SH2 along the harbour.   Both of those are through narrow corridors with few or no alternatives.

P2G map 1

Source: Google Maps

The logical thing to do, then, as proposed in various studies since about 1991, is something like this:

P2G map 2

Source: Google Maps

Traffic wanting to get between the SH1 corridor in the west and the SH2 corridor in the east can “cut the corner” of Ngauranga, taking pressure off those two chokepoints.

If there’s a truck flipped in Ngauranga Gorge, traffic can go up SH2 and across P2G. Likewise if there’s a crash along SH2 traffic can go up SH1 and across P2G back to Petone. All good, and everyone’s back about their business with minimal fuss.

But 7km of road is Not Enough Road. More Road = More Resilient, remember. So what NZTA is proposing is this:

P2G map 3

Source: NZTA Presentation to Chief Executives Group, November 2014, released under OIA

We’ll turn the whole thing north-south (because clearly a north-south road is how you solve an east-west problem); then we have room to double the length. Here are some other “resilient” features:

  • Motorway to motorway interchanges through chains of roundabouts!
Source: NZTA/Opus

Source: NZTA/Opus

  • Motorway to motorway interchanges via two-lane local streets! (and roundabouts!)
Source: NZTA Petone to Grenada Project website

Source: NZTA Petone to Grenada Project website

  • “Bypasses” with one-way ramps that force you 12km out of your way!
P2G map 6

Source: Petone to Grenada Scoping Report, February 2014

  • Motorways next to other motorways! (More Roads = More Resilient!)
Source: NZTA Petone to Grenada Project website

Source: NZTA Petone to Grenada Project website

  • Roads on unstudied active fault lines!
Source: GNS Active Faults database

Source: GNS Active Faults database

  • 80 meter deep canyons through the Wellington Fault Scarp!
Source: HC8/9, Grenada-Petone Link and SH58 Upgrade Economics, Sinclair Knight Merz, April 2010, released under OIA

Source: HC8/9, Grenada-Petone Link and SH58 Upgrade Economics, Sinclair Knight Merz, April 2010, released under OIA

  • In Petone!
Source: Petone to Grenada Link Road Preliminary Geotechnical Appraisal, September 2013, released under OIA

Source: Petone to Grenada Link Road Preliminary Geotechnical Appraisal, September 2013, released under OIA

NZTA has taken a reasonable solution to Wellington network resilience woes and “made it better”, in the process negating the very function the road was originally supposed to serve. In the meantime, genuine improvements to the earthquake and natural hazard resilience of the roading network are left to languish.

Source: (ex. labels) Wellington Region Road Network Earthquake Resilience Study, Opus, August 2012

Source: (ex. labels) Wellington Region Road Network Earthquake Resilience Study, Opus, August 2012

I’d really recommend reading her entire series on the motorway. It seems like NZTA is pursuing a more expensive option that delivers much worse outcomes. In particular, Tamara argues that better results could be achieved through upgrades to a few problematic bits of the existing State Highway 58.

Meanwhile, University of Auckland statistician Thomas Lumley (who writes the excellent StatsChat blog) has been digging into NZTA’s options assessments on the project. He’s found that the agency has made some basic statistical errors in its weighting of evaluation criteria. The effect seems to have been that NZTA’s chosen the wrong project, for the wrong reasons:

If you have to make a decision with several options, each with different types of positive and negative effects, it’s going to be hard. Techniques for breaking down complex decisions into sets of simpler questions are very valuable, but it’s important that the way you break down the problem and recombine the answers fits with how you answer the simpler questions.

I’ve been pointed to what looks like an unfortunate example from the NZTA, in assessing options for the Petone–Grenada link road to be constructed near Wellington. The road comes in two sections: from Petone to the eastern section of Lincolnshire Farm, and from there to Grenada. According to the scoping report (PDF), these can be decided independently of each other, so there’s an ideal opportunity to simplify the decision making.  NZTA describes four options P1 to P4 for the first section, and four options A to D for the second section.

I would have expected them to just make independent recommendations for the two sections, but what they actually did was more complicated. First, they looked at the P options and decided based on four criteria that P4 was best.  They then looked at A+P4, B+P4, C+P4, and D+P4 for the same four criteria, and said in a footnote (p172) “Upon combining one of Option P1, P2, P3 or P4 with one Option A, B, C or D the effect more towards the negative takes precedence.

This can only make sense if the harms or benefits weren’t independent.  Sometimes that’s possible. In particular, one of the criteria was “resilience”, and you might argue that it doesn’t matter how robust the second part of the road is when the first part is under several meters of rock and mud, or filled with bumper-to-bumper traffic jams. It could make sense to take the worst value of the two sections when assessing resilience: but people who know more about Wellington-area transport than I do still seem dubious.

The same argument certainly doesn’t apply for the other criteria: archaeological,  ecological,  landscape/visual impact, and transport benefit/cost. If one section of the road is an environmental nightmare, that doesn’t make the environmental impact of the other section unimportant. If one section of the road is unavoidably ugly, that doesn’t excuse making the other section ugly. If one section destroys an important heritage site, it doesn’t mean the other section doesn’t have to care about preservation of the past. If one section is ridiculously expensive it doesn’t mean the costs are unimportant for the other section.

The impact of decomposing and recombining the evaluation as they did, is that any criterion where P4 was bad becomes much less important in choosing among options A to D. P4 was very bad on the landscape/visual criterion, and moderately bad on ecology.

By now you should be expecting the punch line: evaluated independently, options A and B look good because they score well on ecology and landscape/visual criteria. Evaluated in combination with P4, they look terrible, because the ecology and landscape benefits are masked by the “more negative” combining rule. That’s a problem with the combining rule, not with the road. Here’s a colour-coded version of the information in Table 23-19, p182 (from T. Duran)

P2G separate and combined option assessment

Not only is the combining rule obviously missing some information, it’s not even internally consistent. If the evaluation had been done in the opposite order they might well have chosen A first, and then looked at A+P1 to A+P4. Even D was what they’d chosen first, P3+D would then look slightly better than P4+D.

It’s very tempting to look for ways of combining preferences that don’t rely on numbers, just on orderings, but in most cases they aren’t available, and attempts to do it leave you worse off than before.

This evaluation wasn’t set up to focus only on resilience — even assuming that the resilience assessment is valid, which I hear is also being questioned — it was set up to value the four criteria equally. It really looks as though a minor detail of the approach to simplifying the evaluation has had a large, accidental effect on the result.

Thomas’s words are gentle but suggest serious methodological errors in NZTA’s project selection. Taken together with Tamara’s critique of the agency’s evaluation of the resilience impacts of the Petone-to-Grenada road, it really makes you wonder what’s wrong with NZTA’s decision-making.