We need to stop lying to ourselves about congestion

Without getting back on the topic of pohutukawas or St Luke’s Road again, I did notice something funny in the statement that Greg Edmonds, Auckland Transport’s Chief Operating Officer, made in Metro Magazine in response to the issue:

The founding premise of the Auckland super city was that the city’s congestion was costing $1 billion a year in lost productivity and this had to change.


Auckland Transport (AT) was created to solve the congestion problem…

Some people might think that this is a slightly too narrow view of Auckland Transport’s mandate. Whatever. Fair enough.

However, there is actually a much more serious problem with Mr Edmonds’ comments. Simply put: the notion that we can “solve the congestion problem” is not at all realistic. (Unless we are willing to try out road pricing, which is unlikely given the tepid response to the last few studies of the issue.)

I don’t want to pick on Mr Edmonds in particular. It’s common to hear politicians, bureaucrats, and advocates from all over say similar things. We constantly hear that Project X or Project Y will “fix congestion” or “solve gridlock” or “save us [some unthinkably large amount of money] in congestion costs”.

As an economist, I’m baffled by these statements. The empirical evidence on congestion overwhelmingly shows that it is not possible to reduce it by building more roads. This is because people change their behaviour in response to bigger roads. They shift from walking to the store to driving there; they buy a house further out of town; they travel at different times.

Here’s what two North American economists, Duranton and Turner, had to say on the topic after undertaking a comprehensive, multi-decade study on induced traffic in US cities:

Our data suggests a ‘fundamental law of road congestion’ where the extension of most major roads is met with a proportional increase in traffic. Not only do we provide direct evidence for this law, but also show find evidence that three implications of this law; near flat demand curve for VKT, convergence of traffic levels, and no effect of public transit on traffic levels.

All earlier studies, such as this comprehensive 1998 study of 70 US metro areas over a 15 year period cited by walkable city advocate Jeff Speck, have come up with identical findings:

Metro areas that invested heavily in road capacity expansion fared no better in easing congestion than metro areas that did not. Trends in congestion show that areas that exhibited greater growth in lane capacity spent roughly $22 billion more on road construction than those that didn’t, yet ended up with slightly higher congestion costs per person, wasted fuel, and travel delay.

Consequently, all we can realistically do about congestion is to give people good alternatives to participating in it. Other modes, such as grade-separated rapid transit and walking and cycling, do not get congested in the same way as roads do. While the research shows that providing alternatives to driving does not necessarily reduce road congestion, it does give people a way to reduce their exposure to it.

In light of these fundamental economic realities, it is essential that transport agencies stop talking about “fixing congestion”. This is nothing more than a dangerous fantasy.

Suggesting that we can solve congestion creates unrealistic hopes among the public. Every time a politician or transport agency opens a new road and promises that it will reduce congestion or speed up people’s journeys, they are feeding expectations that can never fully be met.

The result of this is that transport agencies are constantly dealing with demands for more roads that will not actually deliver long-term solutions to the problem of congestion. This sets the transport profession up to constantly fail to satisfy people’s desires and demands. This has to be a tremendously disheartening situation to be in.

My personal view is that instead of talking about “fixing congestion”, transport agencies should instead promise to deliver outcomes that are actually achievable.

This could include, for example, committing to deliver transport choice to underserved areas of the city by investing in rapid transit infrastructure, frequent bus services, and safe walking and cycling infrastructure. While transport agencies would have to work hard to deliver on all this, they could expect that the end result would be more transport choice for residents.

Transport agencies could even commit to some traditionally roads-centric goals, like, say, building new roads to enable the development of a new subdivision at the edge of the city. At least, as long as they weren’t making unrealistic promises of fast, frictionless commutes to the future residents…

Freeing us from traffic

Yesterday the Herald ran a fantastic opinion piece from Dr Jamie Hosking who is a senior lecturer and health and transport researcher at the University of Auckland. As he says at the end, it’s “a timely reminder for the Auckland Council as it considers whether to reduce spending on big new roading projects. Liveable cities don’t try to make traffic go faster. They free people from traffic.”

We all hate being stuck in traffic. The usual response to congested roads in New Zealand, especially in Auckland, is to make the congested road bigger – turn a two-lane road into four.

Although at first sight this seems to make sense, it’s not the only solution, nor the best.

Building more roads in response to congestion is often likened to dealing with obesity by loosening your belt. This is a useful comparison because it shows that building bigger roads does not fix the underlying problem. The underlying problem is that there are too many cars.

But building more roads is even worse than loosening your belt because it encourages people to drive more.

Transport planners use terms such as latent demand and induced traffic to explain this, but it can be explained in plain language.

If a city’s population is growing, a road will become busier. This continues until the amount of traffic at rush hour can’t grow any more. The congestion stops any more people from using the road.

In other words, a congested road puts people off using it. So, if the Auckland Harbour Bridge is congested in the morning, people are more likely to catch the bus to work instead of driving across the bridge. If they were thinking of going shopping in the CBD, they might decide to go somewhere local instead to avoid the traffic. Or, if the trip wasn’t that important, they might just stay home.

The flipside is that if we make a road less congested, more people will drive on it. So if a road is expanded from two to four lanes, traffic speeds will increase at first, but as more and more cars use the road, congestion will grow again. The end result is a four-lane road with the same congestion and speeds as the original two-lane road.

If all we care about is how fast the cars are going, we’re no better off. We’re worse off. Because on the four-lane road, there are twice as many people stuck in traffic. That means twice as much time lost.

This reminds us that we need to think less about roads and cars, and more about getting people to where they want to go.

In Auckland, we’ve been building more and bigger roads for years, but at peak hours our roads are still clogged. If we remember that bigger roads encourage more cars, this isn’t surprising at all.

If we start thinking about people, instead of roads and cars, the alternative becomes obvious. Our goal shouldn’t be free-flowing car traffic, because we know in the long-term it will never happen. Our goal should be free-flowing people.

We’ve talked quite a bit about induced demand in the past as well as cities which are now starting up pull out some parts of their motorway networks and seeing no negative impacts from having done so. For example from this


to this


The goal of free flowing people is a key driver behind why we created the Congestion Free Network and even why we named it Congestion Free as it refers to the people being free of congestion. He then goes on to suggest something very similar to the CFN.

One way to achieve this is building rapid public transport. This needs its own protected space, like trains, or buses on a busway.

Rapid public transport is a great answer to congestion, because the congestion proves there are a lot of people trying to go in the same direction, and this is exactly what public transport needs.

Another way to get free-flowing people is better infrastructure for walking and cycling. For example, routes through parks and greenways help people walk and cycle away from congested roads.

Maybe the best way of all is to design our neighbourhoods and cities better. The more things people can do locally, instead of having to travel across town, the less time they will spend stuck in traffic. Road building undercuts local businesses and services, because it encourages people to drive across town to go shopping instead. The opposite is intensification, which brings more people into a town centre to live in high-density housing and apartments, and attracts more local businesses and services.

That’s why neighbourhoods and cities that want to be more liveable are making roads smaller. This frees space for busways, cycleways or new public areas, it pushes people out of their cars or it encourages them to do things locally instead of travelling across town. The result is fewer people stuck in traffic, healthier local businesses and neighbourhoods that are much better places to live.

I think that if there’s one area he missed it was in relation to the potential benefits investing in the movement of people could have for the movement freight. A network like the CFN would allow us to be bold with how we deal with trucks and other commercial vehicles. In particular we could look at doing measures like the introduction of freight lanes on key routes or other similar measures that speeds up the movement of goods without spending money on wider roads only for it to be gobbled up by cars with only a driver in them.

So yes let’s start focusing on people.

Let’s define “congestion” properly

An article in Toronto’s Globe and Mail newspaper just over a week ago, using the rather provocative title of “Sick of Congestion: build roads not transit” has unsurprisingly led to a lot of fisking of the information contained in the article – particularly around the different ways of defining congestion and how easily they can be misused. A good example of a response is this from Jarrett Walker.

Essentially, the argument put forward in the article is that when we look at cities around the USA (and internationally), at first glance the data appears to be showing that cities which have built a lot of freeways in the past few decades have lower levels of congestion than those which haven’t. Here are the key paragraphs:

This connection between road construction and congestion has been most comprehensively studied in the United States. There, 30 years ago, the Texas Transportation Institute at the Texas A&M University created an annual Travel Time Index (TTI) that estimates how much time traffic congestion adds to commuting by comparing actual travel times of commuters in different cities with the time it would take to travel the same distances in the absence of congestion.

Over the decades of its existence, the TTI has revealed some fascinating shifts. In the early days of the index, Phoenix, for example, had the 10th worse congestion among major urban areas in the U.S., despite being only 35th in population. It has more than doubled in size in the ensuing decades (it is now the 12th largest urban area in the U.S.), but its traffic congestion has fallen to 37th.

What explains this major improvement? A huge expansion of public transit? Hardly. Try a major road-building program. Something similar happened in Houston.

At the other end of the spectrum, Portland, Ore., has pursued road-skeptical policies similar to many major Canadian cities. The result is markedly worsened commuting times. According to the TTI, over the past 30 years Portland has gone from having the 47th worst congestion in the U.S. to the sixth worst.

Something in the next paragraph jumped out at me when first reading it – when mention was made of New Zealand cities as examples of those that had high congestion and hadn’t built many urban freeways.

Now data are starting to emerge that allow us to compare commute times among similar rich-world industrialized countries in Western Europe, the U.S., Canada, Australia and New Zealand. The results are not encouraging for the anti-car crowd. The worst urban congestion in this group of countries is in New Zealand, followed by Australia, countries that have invested relatively little in urban freeways.

If Auckland, with our gigantic spaghetti junction and motorways to just about every corner of the city, is an example of us not having invested much in ‘urban freeways’, I’d hate to see a place with lot of them – although Toronto’s Highway 405 (below) is pretty bad. I actually had a quick look at some figures from US cities with populations greater than 1 million people and from what I can tell based on some admittedly very rough calculations is that the size of motorway network would probably put us within top 10 US cities. Might have to look into that in more detail for a future post.

But the strange mention of New Zealand aside, the real issue with the article is its reliance upon congestion information from the Texas Transportation Institute that is decidedly dodgy in how it’s applied. Let’s pick up on Jarrett Walker’s criticism of the source data:

TTI believes that traffic congestion is a valid measure of people’s ability to access the resources of their city.  They do not measure actual travel times for all people, or the liberty and economic liberty that a good urban transporation system offers.  They apply these things as factors to a degree, but their bottom line is road congestion.

Specifically, their metric is the difference in travel times, by car, between travel time on congested roads and the same roads in a free-flow condition.   In other words, their baseline utopian condition is abundant free-flowing roads at all times of day.  (That condition is actually an economic impossibility in a city above a certain size with a healthy economy and no road pricing.)

Once you insist on measuring congestion, and against that fantasy baseline, you can get absolutely everything backwards…

… If you count everybody’s commuting time, Portland is ahead of most US metros.   … it is only congestion that is worse.  Yes, like all dense cities, Portland has exactly as much congestion as it makes room for, but it has low overall commute times, mostly because its carefully mixed density allows many people to commute very short distances.   Remember, if you are measuring car congestion, Portland’s transit riders and cyclists and the many people who can walk to work simply do not exist.  Crowley disses “congested” Vancouver for the same reason, even though Vancouver is the only Canadian metro where the long-term trend is toward shorter commute times, due to continued consolidation of housing and business around transit.

Jarrett sort of dances around the key point here while hinting at it in a number of ways. This key point is that for many people in the Portlands or Vancouvers of this world the level of basic congestion is irrelevant because they’re not affected by it. They’re walking, cycling, on a bus (as long as it’s in a bus lane or on a busway), a tram, a train or whatever. They’re not in the congestion.

This is the key point of the Congestion Free Network: it provides people with the ability to ‘opt out’ of congestion. This approach highlights that there are two elements to congestion:

  • How bad is the congestion? (Congestion intensity)
  • What proportion of people experience the congestion? (Congestion exposure)

It is the combination of these two elements which is what really matters – the actual effect of congestion can be increased or decreased not only through its intensity (which is all that the TTI measure, and arguably not that well either) but also through changing the proportion of people experiencing congestion. It seems that transport planners and particularly transport engineers focus so much on trying to reduce the intensity of congestion, even though this is nearly impossible due to induced demand, whereas the long-lasting way of reducing congestion is to provide ways to remove people from the congestion.

This means that a focus on cycleways, bus lanes, rapid transit and freight lanes (because it can be very important to shift goods around in a way that’s unaffected by congestion) are the true ways of reducing the actual effect of congestion. They’re also the only long-lasting ways of doing so. Todd Litman focuses on this distinction in his recent piece on Planetizen:

…the Texas Transportation Institute’s Travel Time Index, the INRIX Traffic Scorecard, and TomTom’s Traffic Index only measure congestion intensity, the degree that traffic declines during peak periods. Such indicators do not account for exposure, the amount that people must drive during peak periods and therefore their total congestion costs. Intensity indices are useful for short-term decisions, such as how best to cross town during rush hour, but are unsuited to strategic planning decisions that affect the quality of transport options or land use development patterns, and therefore the amount that people must drive. For planning purposes, the correct indicator is per capita congestion costs.

For example, a compact, transit-oriented city may have a 1.3 Travel Time Index (traffic speeds decline 30% during peak periods), 60% automobile commute mode share, and 6-mile average trip lengths, resulting in 34 average annual hours of delay per commuter; while a sprawled, automobile-dependent city has a 1.2 Travel Time Index, 90% automobile mode share, and 10-mile average trip lengths, resulting in a much higher 45 average annual hours of delay. Intensity indicators imply that the compact city has worse congestion due to greater peak period speed reductions, although its residents experience lower total congestion costs because they drive less during peak periods.

I talked about TomTom’s Traffic index here.

As part of the next phase of promoting the Congestion Free Network, we are going to focus strongly on expanding this new approach to defining congestion – so that it can actually be a useful measure of transport success, rather than something that suggests we do stupid things like building more (or bigger) urban motorways.

Highway 401 in Toronto

The perils of ignoring induced demand

Streetsblog draws our attention to an interesting Danish study into the impact of induced demand on the cost-benefit analyses of motorway projects.

Here’s the abstract of the article:

Although the phenomenon of induced traffic has been theorized for more than 60 years and is now widely accepted among transport researchers, the traffic-generating effects of road capacity expansion are still often neglected in transport modelling. Such omission can lead to serious bias in the assessments of environmental impacts as well as the economic viability of proposed road projects, especially in situations where there is a latent demand for more road capacity. This has been illustrated in the present paper by an assessment of travel time savings, environmental impacts and the economic performance of a proposed road project in Copenhagen with and without short-term induced traffic included in the transport model.

The available transport model was not able to include long-term induced traffic resulting from changes in land use and in the level of service of public transport. Even though the model calculations included only a part of the induced traffic, the difference in cost-benefit results compared to the model excluding all induced traffic was substantial. The results show lower travel time savings, more adverse environmental impacts and a considerably lower benefit-cost ratio when induced traffic is partly accounted for than when it is ignored.

By exaggerating the economic benefits of road capacity increase and underestimating its negative effects, omission of induced traffic can result in over-allocation of public money on road construction and correspondingly less focus on other ways of dealing with congestion and environmental problems in urban areas.

Digging a bit further into the article,  we see that concern around the accuracy of assessing benefits of transport projects is spreading around various academics involved in this field:

Within the community of scholars and practitioners dealing with cost-benefit analyses (CBAs) of transport infrastructure projects, there is widespread acknowledgment of a number of flaws in the existing use of this method (Ackerman and Heinzerling, 2004; Mackie, 2010; Næss, 2006; Salling and Banister, 2009, van Wee, 2011). In a recent seminar4 on the use of CBAs in the transport sector, virtually all presentations highlighted problems associated with the method and its use in planning and decision-making, including the valuation of traffic time, environmental pollution, deaths and injuries from traffic accidents, and not the least the forecasts of future traffic volumes and time savings (Debenardi, Grimaldi, and Beria, 2011; Mackie, 2010). Estimates of construction costs and traffic demand have also often turned out to be highly inaccurate and most often too optimistic (Flyvbjerg, Bruzelius, and Rothengatter 2003; Holm 2000; National Audit Office 2007; Odeck 2004; Parthasarathi and Levinson 2010; Welde and Odeck 2011). Yet, there was the almost unanimous opinion of the participants of this seminar that the solution to these problems was to refine the CBA method and its usage, not to shift to a different way of evaluating project proposals. Apparently, the problem is not that the medicine has been misplaced, but that the dose has not been appropriate.

For road projects, the accuracy of traffic demand forecasts are crucial to the validity of any subsequent impact assessments, whether this is in the form of CBAs or other appraisal techniques. These forecasts form the basis for estimates for a wide range of impact factors, including time savings, emissions, and noise. Since traffic demand seems to be underestimate for road projects on average (Flyvbjerg, Bruzelius, and Rothengatter, 2003; Holm 2000; Næss, Flyvbjerg, and Buhl, 2006; Parthasarathi and Levinson, 2010; Rodier, 2004; Welde and Odeck, 2011), one might assume that this would cause benefits to be underestimated as well. However, underestimating the demand for road traffic also means that the expected time saving benefits might not materialize due to additional traffic, since demand could become so high on the new infrastructure that congestion occurs. It is this latter effect that will be the focus of the present article.

For transport projects there is a range of impact factors that lend themselves to appraisal via CBA, but in practice only a few of them have any noteworthy impact on monetized appraisal results. This is especially the case of projects concerned with expansion of road capacity. Usually, travel time savings make up most of the expected benefits for new road projects (Banister 2008; Mackie, Jara-Diaz, and Fowkes 2001). For example, in the CBA of a recent proposal for a new motorway in Denmark5, travel time savings amount to 84 % of the total benefits on average. The price and volume of time savings are thus without comparison the most decisive benefit parameters in a CBA for road capacity expansion. Although the monetary values given to time savings are contested and represent an important source of inexactness, this will not be dealt with in the present study. Instead we shall focus on the second source of uncertainty, which is the expected savings in terms of reduced travel times for drivers as a result of added capacity. More precisely, the purpose of the paper is to illuminate how the neglect or underestimation of induced traffic can seriously distort the results of cost-benefit analyses of road projects in congested urban situations.

If you’re interested in learning more about what induced demand is, and how it can have a destructive effect on the justification for roading projects, the article is well worth a read. I suppose the question that’s in my mind a lot is whether the bigger problem with estimating future demand is that we’re going to over-estimate it (due to stagnating traffic growth), or under-estimate it due to induced demand. With neither of these scenarios representing good news for benefits from roading projects, and with so much money at stake, perhaps it’s worthwhile understanding all of this a bit better.

I wonder if NZTA read this kind of thing?

Congestion: Cause or Effect?

Todd Littman of the Victoria Transport Policy Institute has put together a really useful critical analysis of the way we measure congestion and how this affects the general approaches taken to reducing congestion – typically seen (especially when undertaking cost-benefit analyses of transport projects) as the main justification for transport expenditure. The article is a fairly easy read, if somewhat lengthy, so I won’t go through all the details. Here’s the abstract: To keep this post from getting too technical and detailed, I’ll largely focus on the pictures and graphs that are in the article. This is a particularly relevant graph, because it means that unless our transport demand modelling has been updated to take account of the pretty radical change to traffic volumes (this is the USA, but we’ve seen similar trends in New Zealand) in the past few years, chances are we’re going to be enormously over-estimating traffic volumes (and therefore congestion) in the future. There is a real danger of failure to see change, even after it has happened, by people who have spent their careers under one orthodoxy. And I believe that is what is happening now at the MoT, if the reports I hear are true, of officials there arguing that there is no point in changing policy just because of recent trends.  Well how long do ‘recent trends’ have to continue before they become the relevant? 5 years? 10 years?: Some of the dip is obviously due to the economic situation over the past few years, but other aspects might be more structural – relating to demographic change, changing land-use patterns, significantly higher fuel costs and general cultural change. Littman’s article notes that, should this down-turn in traffic volumes prove to be long-lasting and structural, it really changes the way we approach the issue of congestion in the future:

It made sense to invest significant resources in roadway when the basic roadway system was first developed and automobile travel demand was growing rapidly. During that period highway projects provided high economic returns, consumers reaped large benefits, and there is little risk of overbuilding roadway capacity since it would eventually fill. But once the road system matures, so there are high-speed highways connecting regions and a well-developed network of paved local roads, the marginal benefits of incremental roadway expansion tend to decline.

Transport planning and financing practices will need to change in response to reduced growth in vehicle travel demand and congestion problems, and increasing demand for travel by alternative modes. This will require reducing emphasis on congestion problems and roadway expansion and increasing emphasis on other planning objectives and other types of transport system improvements. 

Most of our long-term thinking is still based on the assumption that traffic rates will grow and grow. To an extent, in a place like Auckland where the population is growing quickly, that is likely to be somewhat true – but it seems reasonable to expect that per capita vehicle travel may well have peaked, meaning a slower rate of traffic growth in the future. This is a good thing, as it means we can hopefully get away from an endless game of adding capacity to the road system only to see it fill up over and over again, hoping that perhaps this one last time the extra lane might solve congestion for good (like a drug addict wanting just one last hit?).

Of course, in the real world (rather than the fantasy world of Ministry of Transport policy analysts and NZTA traffic engineers) we understand that  building more roads simply leads to inducing more traffic – meaning that more often than not you find yourself back to square one rather surprisingly quickly (ever noticed that the widest sections of Auckland’s motorway network often also seem to be the most congested?). This is well illustrated in the diagram below: Now it’s probably a bit unfair to say that there’s no benefit from allowing more vehicles to travel at the time they want to travel (as induced demand provides for) even if it means the road is still congested. But what Littman’s research shows is that there are diminishing returns when it comes to the value added – in that a lot of the people “induced” to using the road at peak times wouldn’t probably be quite willing to travel at other times, or via other modes, to avoid the peak congestion. The article goes on in quite a lot of detail about how we might better focus on reducing the impact of congestion – through building public transport, pricing roads and undertaking smarter land-use policies. There’s enough detail in those to probably fill a future post, but there’s one last graph that certainly caught my attention, because it looks at the wide variety of different costs – related to travel – that individual people face: What this graph shows really cleverly is that, in the broader scheme of everything, traffic congestion doesn’t really cost each of us that much money. Sure, it’s an annoyance, but then so is losing $2,000 a year in depreciation on our vehicles, having a cost to society of almost $2,000 a year from crash damages, paying (through higher rent, prices or lower salaries) parking subsidies and so forth. Yet for some reason our transport policy seems to be utterly obsessed with minmising the cost to us of what’s really quite a minor matter – only the sixth most important issue in terms of cost magnitude.

So automatic, so deep is the group-think at the MoT and NZTA, not to mention their close buddies in the road lobbies like the Road Users Forum and the AA, that the only possible answer to all questions of  movement is to expand the road space, that these institutions are spending uncritically on projects with ever decreasing returns on the investment. Of course the pressure from their political masters is currently very great too and it all adds up to a deeply unsophisticated and wasteful approach to infrastructure investment and a less efficient and poorer city.

Of course, for some road users (freight movement and business travel comes to mind) congestion and unreliability have a much greater impact. But there really is something incredibly stupid and naive about over building one system that forces everyone, no matter how reluctant, into a car and in the way of these vital road users. Under this ideology it’s almost like the MoT and NZTA are really in the congestion business. Where is the analysis that shows that getting lower value trips onto public transport through investment in providing quality services wouldn’t be more cost effective than trying to squeeze ever more traffic onto already clogged roads? Especially because, as this study shows, congestion isn’t even the biggest burden of auto-dependency.

“Locking in” Vic Park Tunnel’s benefits

The additional southbound lanes over the Victoria Park Viaduct, made possible through the construction of the Victoria Park Tunnel, open to vehicles today. John Roughan’s NZ Herald editorial can barely contain his excitement at this prospect, largely because (he hopes) it will get rid of queue jumpers holding up traffic through St Mary’s Bay. While I must admit a small part of me is hoping for the motorway opening to be yet another congestion catastrophe, this is generally a motorway project that I have supported because it is aimed at eliminating a bottleneck, rather than simply adding capacity and creating a bottleneck elsewhere in the system.

One of the biggest potential benefits from this project was highlighted in the comments section of my previous post on the motorway opening: that connections between the northern motorway and the Port would become more attractive, removing cross-CBD traffic from Customs, Quay and Fanshawe streets. In many ways, this benefit of the project is similar to how the biggest benefits the Waterview Connection proposal will bring is through a reduction in local traffic on roads like Mt Albert, Blockhouse Bay, Sandringham, Dominion and Richardson roads.

While Google Maps suggests that someone travelling between the North Shore and the Port/Parnell area would utilise the motorway system, rather than travelling through the heart of town, congestion on and around the viaduct (back to the harbour bridge for southbound traffic, the incredibly slow ramp signal for northbound traffic before it joins SH1) means that much of the traffic takes the red route instead: When the Victoria Park Tunnel is open to its full complement of three lanes for northbound traffic, and any teething issue for southbound vehicles have been resolved, we should see a reduction in through traffic away from the red route (and hopefully also away from Customs Street). However, as with the Waterview Connection, the Hobsonville deviation and the Manukau Connection, the reduction in vehicles on local roads is only likely to be temporary – thanks to induced demand. If there’s way less traffic on Quay Street and Fanshawe Street, then vehicles using other congested routes will shift back to these freer flowing streets. Motorway traffic may also shift back onto the local roads as some people find them to be faster. Over time, if we don’t make some interventions, we could end up back where we started – but now with a congested wider motorway and congested inner-city streets. Such an outcome would undermine what should be one of the biggest benefits of the Vic Park Tunnel project: the removal of traffic from CBD streets to free up more space for pedestrians, cyclists and public transport.

However, if we’re smart we can avoid such an outcome. And, for once, I’m fairly confident that we’ll be able to actually achieve some real benefits if we move quickly. The City Centre Master Plan proposes to significantly increase pedestrian priority along Quay Street by reducing vehicle capacity – exactly the kind of intervention that’s necessary to dissuade vehicles back onto Quay Street once it’s a bit quieter: It’s also a golden opportunity to get rid of the horrific Hobson Street viaduct: Fortunately, this is also given consideration in the City Centre Master Plan: Completion of the Vic Park Tunnel may also be a golden opportunity to look at reallocating a bit of roadspace to buses along Fanshawe Street so we can actually complete the Northern Busway. At the moment we find ourselves in the stupid situation of having citybound buses take as long to complete the last few hundred metres of their journey as they did to get between Constellation and Akoranga stations – something we spent hundreds of millions on speeding up, to go and undermine our investment simply because we can’t be bothered putting bus lanes along remaining sections of city streets.

The key point is that we have to move quickly in advancing these projects to take advantage of the ‘window of opportunity’ to really lock in the benefits of the Victoria Park Tunnel project. If we stuff around for a few years then we will lose this window, and implementing projects that reallocate roadspace away from vehicles will be that much harder.

The end of freeways?

An interesting Salon.com article looks at a growing US trend: the removal of urban freeways.

Right now, several U.S. cities are scheming to shut down major freeways — permanently. In the push to take back cities from cars, this is what you’d call throwing down the gauntlet.

The drive to tear down the huge freeways that many blame for the inner-city blight of the ’60s and ’70s is one of the most dramatic signs of the new urban order. Proponents of such efforts have data to show that freeway removal is not at all bizarre, that we can return to human-size streets without causing a gridlock apocalypse. And that may be true. But pulling down these shrines to the automobile also feels like a bold rewriting of America’s 20th-century urban script: Revenge of the Pedestrian. This time it’s personal.

Quite a few freeways have been removed from American cities: typically through a process by which the original one was so badly maintained (or of relatively poor design) that it fell down (or was pushed by an earthquake or other natural disaster), and the best thing agreed upon to do was to simply not rebuild it. The Embarcadero Freeway in San Francisco is a classic example of this:

 Few urban design initiatives can instantly transform a large swath of a city like building (or unbuilding) a freeway. San Francisco saw this in 1991, when, ahead of the tear-down trend, the city demolished the bay-adjacent double-decker Embarcadero Freeway after it was damaged in an earthquake. Today, the area where the Embarcadero once stood has evolved from a forbidding dead zone to a bustling waterfront and tourist magnet. Standing there now, you’d never guess it was once the site of 16 lanes of through-traffic.

However, it seems that increasingly the option of removing freeways is being given closer examination – even when they haven’t been damaged by natural disasters or fallen down for one reason or another.

Now, other cities want their own Embarcadero miracle. Tony Ortiz lives in Crotona Park East, the Bronx neighborhood made famous when President Carter visited its burned-out ruins in the ’70s. Ortiz, an 84-year-old, white-haired bantam rooster of a man, moved here from Puerto Rico in 1946, and remembers life before the Sheridan Expressway. The sidewalks were “busier with people,” he says, standing in front of his six-story building a block from the expressway. He and his friends boxed in the streets, where he once proudly knocked one of them out cold. But after the Sheridan was built, Ortiz mainly remembers a neighborhood in decline and the stench of arson.

Today, the area, while still poor, has bounced back considerably. And now, New York is studying plans to tear down the Sheridan, which runs along the Bronx River right past Ortiz’s window, and replace it with a stretch of waterfront parkland. It could include swimming pools, soccer fields, a 30,000-square-foot recreation center and housing similar to that which was bulldozed to make way for the freeway back in 1958. 

“But what about the congestion?”  – I hear you all cry. Well that wasn’t a problem for the Embarcadero because it was a half-finished and not fully connected structure anyway. But it seems that many US cities have found they completely overbuilt roads in the mid 20th century, many of which aren’t used particularly much at all these days, even in huge cities like New York.

Where do these grand plans leave the lowly car commuter? In pretty good shape, as it turns out. In case you haven’t been on an urban freeway lately, allow me to blow your mind: They don’t work like they’re supposed to. They’re quick to deteriorate, clogged at all the wrong times and offer little versatility when problems arise — one collision can make 10,000 people late for work. In fact, the dirty secret of freeways is that they don’t reduce traffic, they create it. Ask any urban planner: Give people more roads, and more of them will drive. Studies show that, in most cases, removing a freeway adds only a few extra minutes to commute times. At the same time, most of the freeways currently on the chopping block are underused anyway. (The day I drove to the Bronx to meet Tony Ortiz, the Sheridan was empty enough to walk across.) The drivers-versus-transit-riders stereotype doesn’t hold, either: A study by Renne’s students found that in New Orleans, the vast majority of locals want the Claiborne Expressway gone — including 50 percent of the drivers who use it regularly. “No one’s advocating for putting [the freeway] back” in Milwaukee now that it’s gone, says Norquist, and getting rid of it “killed forever the idea of putting a freeway around the downtown.”

This is a classic case of induced demand, and I do with that any urban planner would be able to understand this concept. From my experience both planners and (most particularly) traffic engineers struggle to understand the concept of induced demand. Traffic modelling systems don’t seem to be able to comprehend its existence and the cost-benefit analysis process presumably ignores it because it’s too difficult.

There doesn’t seem to be too many prime candidates for demolishing motorways in Auckland, somewhat unfortunately. However, the proposals to remove the Lower Hobson Street viaduct would have many similarities – although on a much smaller scale. Step by step, hopefully we can follow what enlightened US cities are doing and start to claw back a bit more of our city from the car.

Vic Park Tunnel – causing traffic jams

It’s tempting to be amused by the various stories that have emerged this week about the new Victoria Park Tunnel causing huge congestion. The obvious amusing argument to make is that, just like we saw with the opening of the SH20-SH1 Manukau Connection, the opening of a motorway has just shifted the congestion or – in this case – actually created an even worse problem than we used to have. Now obviously such conclusions would be a bit premature, as while the Victoria Park Tunnel is open we are yet to see any increase in capacity along the stretch of road – that will have to wait until early next year when a third lane northbound opens and the two previously northbound lanes on the viaduct become southbound.

Yet the problems of the last few days do seem pretty extreme:

Nightly traffic jams on Auckland’s Southern Motorway are still being blamed on drivers’ unfamiliarity with the new Victoria Park tunnel, four days after two of its three lanes were opened.

Traffic was by about 4.30pm today backed up to Otahuhu, at least 13 kilometres south of the 450-metre one-way northbound tunnel. By 6pm the queue had shrunk slightly, with the tail at Mt Wellington.

Queuing to reach the tunnel has frustrated commuters every evening since Monday, when two of the tunnel’s three lanes were opened for the first time, replacing the northbound carriageway of the Victoria Park motorway viaduct.

I somewhat struggle to believe that unfamiliarity would have this effect. Sure it might lead some people to drive a bit slower the first time they pass through the tunnel, or be a bit weirded out by different angles to the beginning and end of the tunnel to what they’re used to – but I struggle to believe that this would lead to the huge traffic jams that have been reported.

NZTA touch on one of the reasons behind the congestion:

In a bulletin issued today, the Transport Agency said there were indications that many commuters who normally travelled home on the Northwestern Motorway were queuing to use the tunnel instead.

I do suspect that quite a lot of people who have avoided the Victoria Park Viaduct in their travels over the past few years – perhaps travelling through Westmere and Herne Bay if they were coming from the west and heading to the North Shore, travelling through the city if they’re coming from the Port/Parnell area as well as travelling via SH16 then SH18 for people heading to the very northern part of the North Shore. With all the announcements about how important the tunnel is and the fanfare which accompanied its opening, I suspect quite a few people thought they could stop avoiding the bottleneck and changed their routes – only to become the congestion. Perhaps people who have left earlier or later than the peak also felt they’d no longer need to do so.

I suspect what we’re seeing is a classic case of induced demand, but weirdly almost a case of “perceived induced demand” because there hasn’t been an increase in capacity (yet), just a huge misunderstanding by the general public. NZTA are correct that this will “settle down” over the next few days and weeks, but once the third northbound lane is added I suspect that things will also “settle down” to the same level of congestion as we had before the project was constructed.

And remember, compared to most motorway projects, this is one that makes sense.

Speed versus throughput

Somewhat picking up on the point I was trying to make with yesterday’s post regarding how the biggest benefit of the City Rail Link is how it simply massively increases the capacity of Auckland’s transport network, particularly the capacity of the network for trips to the city centre, here’s an interesting article that analyses the issue of whether transport network improvements should be designed around making trips faster (time savings benefits) or whether they should be based around simply increasing throughput:

There’s an old joke in computer science circles: never underestimate the bandwidth of a truck full of tapes. That is, if you want to move a large amount of data from one point to another, but you don’t care how long it takes to get there, the most efficient way to do it is to put the data on a removable media (magnetic tape in the old days, hard drives or DVD-R’s today) and drive them across the country. The freeway system becomes a high-throughput, albeit high-latency, data network.

Exactly the same point applies when you’re comparing a freeway to a grid of city streets. A couple of commenters replied to Sunday’s post by claiming that freeways are essential for moving people and goods into the city center. This argument confuses speed with throughput.

For throughput purposes, what you care about most is the number of lanes connecting any two points. And for a city grid, this number is huge. Central Philadelphia’s surface streets have around a dozen lanes in each direction. This is enough lanes that city streets tend not to be major bottlenecks during rush hour. You’re more likely to find congestion on the freeways themselves, or at the points where the freeways intersect with the street grid.

So urban grids provide plenty of throughput. What they don’t provide is speed. At non-rush-hour times, freeways shave 10 or 20 minutes off the time it takes to get from an outer suburb into the city center. But from an economic perspective, it’s not clear how important this is. First, as already noted, those time savings come at the expense of users of other modes of travel who suffer from a less-compact (and therefore less walkable and bikeable) urban core. And second, these time savings almost disappear completely during rush hour, when freeways don’t move much faster than city streets.

Finally, while we’re talking about throughput, it’s important to remember that a subway line offers dramatically higher throughput—between 5 and 15 times, depending on your assumptions—than a freeway lane. It would be essentially impossible to have a city the size of New York rely primarily on freeways to get people in and out of downtown.

Freeways are a great way to move people around the suburbs, and to move people from one metropolitan area to another. But they’re a poor way to move people into, around, or through the urban core. And it was a huge mistake to destroy thousands of homes and businesses in cities like St. Louis and Minneapolis to make room for urban freeways.

Essentially, we have an existing rail network that has heaps of capacity – just constrained by the Britomart bottleneck. Unless we fully utilise the full capacity of the rail network then we’ll place a huge burden on our roading network to “feed” the city centre in the years and decades to come. Building motorways, widening roads, adding super-expensive road tunnels and so forth can’t really provide more throughput to the city centre, unless we plan on demolishing half the place to widen roads and build more parking lots. Even the “speed advantages” that may arise from constructing something like a second harbour crossing would, as the article above notes, achieve little at peak times when inevitably the road would become congested (thanks to induced demand).

Whether or not the City Rail Link “takes cars off the road” is actually irrelevant. What matters is that it dramatically increases the transport ‘throughput’ of the city – particularly (although certainly not solely) along the most congested part of the network: to and from the city centre. Due to this increase in ‘throughput’ it suddenly becomes possible for the city centre to grow and develop, just as (on a different scale of course) New York City’s rail network has enabled that city to grow to such an extent.

NZTA pessimistic about impact of Hobsonville Motorway?

The Hobsonville Deviation motorway project has its open day today, and properly opens for traffic tomorrow morning. This is a fairly critical part of the Western Ring Route and will make a big difference to Hobsonville Road in particular – removing around 80% of the traffic from this road. There’s a fairly informative video of the project here:

What’s interesting though is to look at the tone of much of NZTA’s media activity surrounding the motorway opening. Instead of trumpeting the project as a grand solution to traffic problems in the area – like they have done for previous motorway projects, the main message they’re trying to get through seems to be that people shouldn’t expect the project to be a panacea to solving congestion. For example:

The NZ Transport Agency is reminding drivers to plan ahead for expected changes to traffic patterns when the new State Highway 18 Hobsonville motorway opens in early August.

The NZTA’s State Highways Manager for Auckland and Northland, Tommy Parker says drivers should still expect some delays during the morning and afternoon peaks.

“The new motorway will be a big step forward in providing more reliable travel times and improving safety by moving thousands of vehicles away from local roads, but there will be some hold-ups during the peaks, and it will not stop all congestion in north-west Auckland,” Mr Parker says.

“The Hobsonville project marks another step towards the completion of the Western Ring Route, but there is still a lot of work to be done before we finish this motorway alternative to SH1 and can deliver all of its benefits to drivers,” Mr Parker adds.

Morning queues are expected to occur near Westgate when traffic on the Hobsonville motorway merges with city bound vehicles on the Northwestern Motorway (SH16).

“The Northwestern is already busy in the morning around the Westgate area,” Mr Parker adds.

In the afternoon, queues are expected on the Upper Harbour Highway (SH 18) at the Constellation Drive intersection with the Northern Motorway (SH1). There could also be queues at the Brigham Creek roundabout narrows to one lane heading north-west.

One thinks that NZTA have learned a bit of a lesson from the opening of the Manukau Connection project – which seemed to cause more traffic problems that it fixed due to a huge number of merging lanes.

I had kind of hoped that perhaps this change in approach was due to NZTA recognising that building more motorways tends to only shift congestion, rather than fix it, but it seems that the greater likelihood is to drive home the message of how important they think it is for the massive proposed widening of the northwest motorway to proceed.