Why it’s not possible to build our way out of congestion

Wired magazine recently published a good, succinct explanation of induced traffic. It’s worth reading in full as it hits upon an incredibly important, often overlooked fact: it’s not possible to eliminate congestion by building more roads. Here are a few of the more interesting excerpts:

The concept is called induced demand, which is economist-speak for when increasing the supply of something (like roads) makes people want that thing even more. Though some traffic engineers made note of this phenomenon at least as early as the 1960s, it is only in recent years that social scientists have collected enough data to show how this happens pretty much every time we build new roads. These findings imply that the ways we traditionally go about trying to mitigate jams are essentially fruitless, and that we’d all be spending a lot less time in traffic if we could just be a little more rational.

But before we get to the solutions, we have to take a closer look at the problem. In 2009, two economists—Matthew Turner of the University of Toronto and Gilles Duranton of the University of Pennsylvania—decided to compare the amount of new roads and highways built in different U.S. cities between 1980 and 2000, and the total number of miles driven in those cities over the same period.

“We found that there’s this perfect one-to-one relationship,” said Turner.

If a city had increased its road capacity by 10 percent between 1980 and 1990, then the amount of driving in that city went up by 10 percent. If the amount of roads in the same city then went up by 11 percent between 1990 and 2000, the total number of miles driven also went up by 11 percent. It’s like the two figures were moving in perfect lockstep, changing at the same exact rate.

Los Angeles: Sitting in traffic after ignoring supply and demand for over 50 years.

In their excellent paper on the topic, Duranton and Turner describe this as “the fundamental law of road congestion: New roads will create new drivers, resulting in the intensity of traffic staying the same.” Their research also digs into a couple of other related and equally interesting phenomena:

  • Better public transport provision doesn’t actually reduce road congestion – but it does enable more people to move without being affected by congestion
  • Reducing road capacity has no measurable impact on congestion – if less road space is available, people take public transport or active modes instead, or avoid making low-value trips.

Urbanist.co also has some further discussion of Duranton and Turner’s work. The economists go on to suggest economists’ favourite answer to congestion: road pricing. (If you’re interested in reading more about that topic, Stu Donovan and I have written several posts about the economics of road pricing.)

So what can be done about all this? How could we actually reduce traffic congestion? Turner explained that the way we use roads right now is a bit like the Soviet Union’s method of distributing bread. Under the communist government, goods were given equally to all, with a central authority setting the price for each commodity. Because that price was often far less than what people were willing to pay for that good, comrades would rush to purchase it, forming lines around the block.

The U.S. government is also in the business of providing people with a good they really want: roads. And just like the old Soviets, Uncle Sam is giving this commodity away for next to nothing. Is the solution then to privatize all roads? Not unless you’re living in some libertarian fantasyland. What Turner and Duranton (and many others who’d like to see more rational transportation policy) actually advocate is known as congestion pricing.

Incidentally, I like Turner’s “Soviet Union” metaphor a lot – I’ve said on occasion that we’re running our transport system like a Polish shipyard.

Lastly, it’s incredibly important to consider induced traffic when making policy recommendations. As I wrote in my review of Alain Bertaud’s talks in Auckland, keeping commute times down is an important part of maintaining an efficient urban labour market. Some people seem to have taken Bertaud’s recommendation that policymakers focus on keeping average car commutes under 30 minutes (and PT commutes under 45 minutes) as a call for more roads. This is a superficially appealing but deeply wrongheaded idea.

Induced traffic means that building roads to keep commute times down will not work. And it will be expensive. While there is often a good case for specific road improvements to remove key bottlenecks or improve safety – the Victoria Park Tunnel comes to mind – Duranton and Turner’s work shows that a strategy of building lots of roads will not succeed in minimising commute times. An alternative approach is needed.

How congested is Auckland, really?

A lot of people think that Auckland’s got bad traffic congestion. The annual TomTom Traffic Index reinforces this perception – it regularly describes Auckland as one of the most congested cities in the region. (We’ve previously highlighted the methodological flaws with TomTom’s numbers – don’t take them at face value!)

However, I don’t think this perception matches up with reality. My experience is that Auckland has much better congestion than cities overseas. It’s incredibly easy to drive in Auckland. I’ve noticed that:

  • Although speeds on motorways and arterial roads drop during rush hour, traffic keeps flowing at a relatively constant rate. It seems uncommon to get totally deadlocked traffic in Auckland – unlike in California, where it’s common to see speeds of under 20km/hr on freeways.
  • The rush hour is incredibly short in Auckland – when I have to drive up to the North Shore after work to visit family, I find that traffic’s basically free-flowing after around 6:30. In other cities serious congestion starts much earlier and ends much later.
  • Counter-peak traffic is shockingly low – on the occasions when I have to drive to Takapuna in the morning, I’ve found that I encounter few queues and no congestion on Pitt St, Victoria Park Tunnel, and the bridge.

Of course, Auckland is more congested than small New Zealand cities with one-tenth its population. That’s only to be expected. But is Auckland really more congested than other large cities overseas?

Jarrett Walker points us toward some new data that can help shed some light on this issue. A recent study (pdf) of commute times in Brazilian cities provides comparative estimates of average commute travel times for thirty large cities all around the world. I used data from New Zealand’s Household Travel Survey to add Auckland to the list. Here are the results:

Avg commute times in large cities

As you can see, Aucklanders enjoy some of the fastest commutes of any city on the list. We travel faster than people in London, Stockholm, Sydney, Los Angeles, and Vancouver. Only Barcelona, a compact city with a densely-developed subway system, offers faster trips to work. (However, it would be good to see a few more Australian cities, like Perth and Brisbane, on the list for comparison.)

While population growth will put some pressure on Auckland’s transport infrastructure, this data suggests that our congestion problems are not severe at all. We look pretty good on Alain Bertaud’s preferred measure of transport accessibility! It seems like the impending completion of Auckland’s motorway network and the significant fall in vehicle kilometres travelled per capita over the last decade has given us a lot of breathing room on congestion.

Rather than trying to solve problems that can’t be observed in the data, we should use this breathing room to invest in real transport choices for Aucklanders. That means getting ambitious about building Auckland’s “missing modes”:

  • A rapid transit network that reaches all parts of the city – starting with the City Rail Link and continuing with something like the Congestion Free Network
  • A frequent bus network that is useful for more Aucklanders, more often – which Auckland Transport is currently doing
  • Safe cycle infrastructure throughout the city – while Auckland Transport and NZTA are starting to deliver great projects like the Grafton Gully and Beach Road cycleways, there are still many holes in the network
  • Good pedestrian-oriented streets – Auckland Council’s shared spaces in the city centre are fantastic but change hasn’t been as rapid in other parts of the city.

What’s your perception of Auckland’s transport problems?

Is less congestion actually a good thing?

It almost goes without saying that congestion is a terrible thing, so bad that it justifies the spending of massive amounts of public money as well as the impact on our cities from widening and building new transport infrastructure to rid ourselves – or at least reduce the level of – this terrible thing that is congestion. So you would expect cities with lots of congestion to be horrible places that are struggling to attract population and have a poor quality of life – while you might expect cities with less congestion to be great places that are attracting heaps of people and have a great quality of life. Right?

Well the reality appears to be quite different, as touched upon in this recent Planetizen article – which compares cities in the USA with some of the highest levels of congestion with those that have some of the lowest. Let’s start with the more congested cities.

Wendell Cox just wrote an essay trying to correlate density and congestion, asserting that density means congestion and congestion is really, really bad (or in his words, “less traffic congestion benefits a metropolitan area’s competitiveness.”)

So logically, the high-congestion cities should be declining, and the low-congestion places should be attracting Americans at a rapid rate. Right? Wrong.

In fact, the lowest-congestion cities tend to be a very mixed bag, while the high-congestion cities are doing relatively well. Cox lists ten high-congestion regions: Los Angeles, Houston, Austin, San Francisco, New York, Seattle, San Jose, Washington, Boston, and Portland. In all ten, the central city of the relevant region gained population between 2000 and 2010. These cities tend to be larger, relatively wealthy, high-cost cities, cities where keeping housing affordable is a bigger problem than demolition of worthless vacant lots.

And in all but two of these ten regions (all excepting Boston and Washington) the central city is more populous than in 1970. In these regions, there’s enough growth for city and suburb alike. Although some of these regions experienced regional population growth of 0-10 percent, not one of them shrunk, and two (Houston and Austin) grew by over 20 percent.

Reeling off cities like Houston, New York, Seattle, Washington, San Francisco and others hardly appears to be a list of US cities which are doing particularly badly at the moment. Even though they are apparently the most congested cities. Now let’s look at the least congested cities:

By contrast, Cox lists ten low-congestion regions: Indianapolis, Oklahoma City, Salt Lake City, St. Louis, Richmond, Kansas City, Memphis, Buffalo, Rochester, and Cleveland. A few of these (most notably Indianapolis, Oklahoma City and Salt Lake City) are doing reasonably well. But five of the central cities in Cox’s “hero metros” lost population in the 2000s (Buffalo, Rochester, Cleveland, St. Louis, and Memphis) and two more gained population in the 2000s but are still less populous than in 1970 (Richmond and Kansas City). In fact, Buffalo and Cleveland even managed to lose population regionwide, and not one of Cox’s high performers grew by more than 16.7% (metro Salt Lake City’s growth rate).

In addition, these low-congestion cities tend to be far more dangerous than high-congestion cities. Their average murder rate in 2012 was 19.5 per 100,000 residents, while the high-congestion cities’ murder rate was only 7 per 100,000—not surprising given the decline discussed above. Only one of the low congestion cities (Salt Lake City) had a murder rate as low as the average for the ten high-congestion cities.

Residents of Cox’s ten low-congestion cities have more reason to worry about dangerous drivers as well as dangerous criminals. I was able to find data for auto-related fatalities for sixteen of the twenty cities in Cox’s two “top ten” lists; the high-congestion cities averaged 4.7 traffic deaths per 100,000 residents in 2011, while the low-congestion cities averaged 9.8. To put the matter another way, the most dangerous of the high-congestion cities (Houston) had 9.1 traffic deaths per 100,000 people, while five of nine low-congestion cities had more traffic deaths per capita than Houston. The second most dangerous high-congestion city (Austin, clocking in at 6.4 deaths per 100,000) had a lower fatality rate than all but one of the low-congestion cities. The least dangerous of the low-congestion cities, Rochester, New York had a higher traffic death rate than five of the seven high-congestion cities.

St Louis, Buffalo, Cleveland etc. at first glance appear to be some of the US cities that have most struggled over the past few decades – losing a heap of population as US manufacturing moved off-shore. The very low congestion levels enjoyed by these places doesn’t seem to have any effect on their relative attractiveness – and seems to be linked with higher murder rates and much greater risk of traffic related deaths.

Michael Lewyn, the article’s author, suggests a possible reason for the connection between low congestion cities and these fairly poor statistics:

Or it could be that policies designed to limit congestion (like widening roads to support high speeds, chopping up downtowns with highways and turning them into giant parking craters) have actually had some positive effect for congestion, but at a heavy cost.

Given that generally we know congested cities are more economically productive, is it time we stopped stressing about this issue so much and focused on things that really matter like levels of accessibility and the extent to which people are able to get around unaffected by the particular road conditions of the moment. Of course that’s a key driver behind the the Congestion Free Network.

CFN 2030A

NZ Initiative’s ideology short-changes compact city debate

The New Zealand Initiative last night released a think piece on the trade-offs of urban form – entitled “Up or Out“. Given the extensive recent debates in Auckland over the Auckland Plan and the Unitary Plan, plus the ongoing issue of housing affordability, it’s helpful to have further analysis and research in this area. Unfortunately, it seems as though some ideological assumptions behind what the NZ Initiative has come up with mask many of their conclusions – somewhat ironic given that one of the key thrusts of the piece is (valid argument) that we need to step back from assumptions and look at the data.

The general approach of the paper is reasonably logical – it analyses some of the benefits of a compact city approach, questions whether they hold true and then compares those benefits to some of the costs. Firstly, looking at agglomeration:

Part of this debate has centred on the agglomeration benefits that come from urban proximity. This is an important discussion point because agglomeration is often cited by planners as the clincher in their argument for compact cities. We do not reject the economic advantages to situating businesses and consumers closer to one other. After all, people and firms in urban areas tend to be more productive than their counterparts in less well-populated areas.

However, these advantages are only detectable as agglomeration benefits when the positives of proximity outweigh the costs of density. This is a balance that any city, regardless of urban form, has to strike if it is to survive. And yet this report shows that the restrictive planning regulations required to deliver the utopian vision of a compact city often tips the balance towards the cost side of the urban ledger.

You can tell from the use of the phrase “utopian vision of a compact city” that they have started out from an ideological position that density is bad.

It does make some sense that agglomeration benefits would have a limit. Yet if we look internationally there are much much larger cities and much much larger urban cores than Auckland – and we find that often it’s the larger cities and larger urban cores which are growing the fastest. The paper even references the significant agglomeration benefits from the CRL’s business case before going on to counter-intuitively suggest that agglomeration benefits in central Auckland appear to be on the wane.

However, the main argument is that the two main negatives of congestion and higher land prices need to be balanced against agglomeration to work work out whether building “up” or “out” is the right approach. Let’s work through the arguments made by the paper on each individually:

Congestion is one of these costs. Traffic congestion data from the United States shows that the most congested metropolitan areas are often the ones that have chosen to pursue compact development. Additionally, quantitative research into transit investments over a 26- year period using data from 74 US metros shows public transport had no long-term impact on road congestion. This stands at odds with the perception that high transit penetration is the solution, not an aggravator of gridlock.

Digging a bit deeper into how they arrived at this conclusion, it seems as though the same methodological mistakes around the measurement of congestion are being made as occurs with the Tom Tom surveys – focusing solely on congestion severity and ignoring issues like congestion exposure. The key point here is that low density car dependent cities may have less intensity/severity of congestion (because they’re so spread out) but whatever congestion there is has to be experienced by everyone because there are no alternatives. In a place like New York, the roads may be congested but to the vast bulk of people this doesn’t matter because they’re walking, cycling or using the subway.

The other gigantic flaw in the paper placing so much emphasis on the issue of congestion is the inconvenient analysis undertaken a couple of years ago which shows the most congested US cities are actually the most economically productive. While it’s more likely economic success causes congestion than the opposite, the congestion doesn’t seem to be holding these places back.

congestion-gdp

The key takeaway from this is that while congestion is annoying and perhaps theoretically should hold back economic performance, if we look at different cities across the USA it doesn’t seem to be doing this. It’s also interesting to compare how we view congestion on the transport network to other areas of society. For example people will choose to go to a restaurant that is busy, even if it involves waiting rather than go to an empty one next door. The crowded and congested restaurant is successful while the empty one is not. If we expand that to a city scale, many people would prefer being in a busy and interesting place with lots of other people than an empty city.

Moving on to land prices, this is seen as the other main negative resulting from a compact city approach that should be balanced against the agglomeration benefits:

Another cost is land. From the perspective of local government in New Zealand, compact cities are desirable because they limit the amount of roading, water and social infrastructure that will need to be provided. Yet by limiting the supply of land, city officials are inadvertently putting a scarcity value on housing in this country, which ranks among some of the least affordable in the world. Equally, the onerous regulations and zoning restrictions required to steer development along the compact model add to the scarcity value of housing. This scarcity value is not limited to housing, and businesses facing higher property costs will pass these on to customers in the form of higher prices, and where they cannot, firms will look to relocate to cheaper areas – a process that is already happening in Hamilton, a beneficiary of fleeing Auckland firms.

We’ve covered off this debate many times before in the past few years as the Auckland Plan and then the Unitary Plan were hashed through in great detail. While limiting the supply of land will theoretically drive up its price, when it comes to housing affordability the issue is the cost of housing more than the cost of land. Furthermore, it’s the cost of housing in particular areas that’s the issue – there’s plenty of affordable housing in Papakura, Clendon, Pukekohe, Waiuku and other far flung parts of Auckland. The huge price escalation is happening in the inner areas – and I can’t quite see how it’s possible to create more land in Grey Lynn or Mt Eden (although of course it’s possible to get more housing out of that land through intensification).

Going back to the paragraph quoted above, what’s particularly odd is the sentence “…the onerous regulations and zoning restrictions required to steer development along the compact model”. Given that enabling intensification is about the removal of zoning restrictions so people have more flexibility to do as they choose with their land, I wonder whether the NZ Initiative has completely misunderstood what planning does and does not do. One is not forced to build terraced houses in the Mixed Housing Urban zone – contrary to popular belief!

The other crazy thing that the paper completely ignores is the gigantic amount of sprawl that has been enabled in Auckland through the Auckland Plan and the Unitary Plan. In one big bang the restrictions on land supply in Auckland have been pushed outwards – even though the result of this is likely to be extremely expensive and not actually what people want anymore. Have the authors been completely ignorant of the Unitary Plan by accident or deliberately?

The paper then briefly touches on health issues – it seems to be cherry picking data and making assumptions based on how cities were in the 19th century to come up with conclusions that seem strangely at odds with what books like “Happy City” suggest. I’ll leave those details to a future post though.

Overall, the paper thinks that it’s come to some grand conclusions:

We have shown through academic research and the historic record that compact cities are not a panacea for the social, financial and infrastructural problems gripping modern cities today. There is no ‘one size fits all’ solution to urban costs, and the sooner we abandon ideology, the sooner we can start developing nuanced solutions to issues like congestion and skyrocketing property prices.

The aim of this report was not to generate specific policy recommendations but to unpack the highly technical argument surrounding urban form changes for the average citizen to participate in the discussion. Still, it is evident at a high level that overly centralised planning and decision making structures are one of the major contributing factors driving urban costs in New Zealand and further afield.

The conclusions are not completely wrong – in highlighting that cities are complex and any ‘one size fits all’ approach is likely to fail. However, in both key areas of critique (congestion and land prices) the paper has made some fundamental oversights – like ignoring the complexities of congestion and its seemingly minimal impact on economic performance, like ignoring the huge amount of additional land supply provided by the Unitary Plan and like ignoring that a key part of the compact city approach is liberalising planning rules within existing urban areas.

Perhaps unsurprisingly, but certainly disappointingly, the paper promises much but inevitably fails to deliver beyond repeating a simplistic ideological perspective on forms of urban growth – falling into the very trap it so merrily accuses others of doing.

TomTom latest meaningless congestion report

TomTom have once again released their meaningless congestion index.

TomTom has announced the results of the TomTom Traffic Index 2013, revealing New Zealanders waste up to 93 hours a year stuck in traffic and that Wellingtonian’s experienced the worst traffic delays during peak hours, spending up to an extra 41 minutes in an hour commute. The Index also revealed that traffic congestion on non-highways is worse than main roads.

The regional results of the Index covers 9 major cities across Australia & New Zealand, with Sydney listed as the most congested city in the region, followed by Auckland and Wellington.

  1. Sydney 34%
  2. Auckland 29%
  3. Wellington 28%
  4. Melbourne 27%
  5. Perth 27%
  6. Christchurch 26%
  7. Adelaide 25%
  8. Brisbane 23%
  9. Canberra 17%

According to the TomTom Traffic Index, Friday morning is the least congested time to commute in New Zealand. The most congested commute was found to be Tuesday morning, and Thursday evening.

There were no cities from our region featured in the top 10 most congested global cities. Auckland, Wellington and Christchurch ranked 22nd, 25th and 42nd respectively in the world’s most congested cities list.

The ranking by overall congestion level in 2013 were:

  1. Moscow 74%
  2. Istanbul 62%
  3. Rio de Janeiro 55%
  4. Mexico City 54%
  5. São Paulo 46%
  6. Palermo 39%
  7. Warsaw 39%
  8. Rome 37%
  9. Los Angeles 36%
  10. Dublin 35%

“The TomTom Traffic Index gives us a great insight into the state of our traffic network. By providing an accurate analysis of traffic flow and guiding traffic away from congested areas, TomTom plays a key role in helping to ease congestion, improving the traffic flow for the cities,” said Phil Allen, TomTom Maps and Traffic Licensing, SE Asia and Oceania.

Here’s Auckland

TomTom Auckland 2014

It’s meaningless for a number of reasons including:

1. It measures the difference in speed between free flow and congested periods. That means cities with lots of all day congestion there isn’t as much of a difference between peak and off peak times and therefore they get recorded as having less congestion.

2. It doesn’t take into account the speeds at which roads most efficiently move traffic – which is not in free flow conditions. This is something picked up on in research conducted for the NZTA by Ian Wallis and Associates

Various definitions of congestion were reviewed and it was found that the concept of congestion is surprisingly ill-defined. A definition commonly used by economists treats all interactions between vehicles as congestion, while a common engineering definition is based on levels of service and recognises congestion only when the road is operating near or in excess of capacity. A definition of congestion based on the road capacity (ie the maximum sustainable flow) was adopted. The costs of congestion on this basis are derived from the difference between the observed travel times and estimated travel times when the road is operating at capacity.

The graph below shows the engineering definition mentioned above.

speed-flow

3. It doesn’t represent all trips on the transport network. We know that even though only about 10% of all trips to work (which excludes trips for education) are made via PT, it still represents a lot of people. For trips to the City Centre more than half of the people arrive by means other than a private vehicle and many of the PT users arrive via the train, ferry or a bus that has travelled along bus lanes. The people on those services or walking/cycling are doing so often completely free of congestion and so their experience isn’t counted.

4. The data only comes from people with a TomTom device and who have obviously had it on. Many people making the same trip on a daily basis or running a regular errand like going to a supermarket are likely to simply leave their GPS systems off. That is likely to distort the overall figures as they may use routes that have less congestion on them than the route the GPS would select.

5. It can disproportionately impact on smaller cities. As an example if you’re in a larger city and have a 45 minute commute however congestion delays you by 30 minutes that equates to a 67% congestion rate however if you are in a smaller city and you’re commute is only 15 minutes and you get delayed by 15 minutes that’s a 100% delay despite the hold up being half of what the bigger city experienced.

It’s starting to get a bit old now however there’s a good piece on the issues with the methodology in this piece from Reuters, some of which is covered above.

Lastly in the email I received about it they also mentioned this

Of the 138 countries surveyed for the Traffic Index, a global average congestion rate of 26% was recorded, placing New Zealand above the average with a rate of 28%. To put things in perspective, Wellington and Auckland even beat out New York City (39th) in the global rankings, a thriving metropolis of 8.4 million.

So we have worse congestion than New York, a city where the majority get around by methods other than a car and who in recent years has been reclaiming road space for pedestrians, cyclists and buses. Perhaps we should do more of that.

Lastly if we really want to move people around then then the Congestion Free Network would allow people to do that completely free of congestion giving some real choice.

CFN 2030A

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

Right on Queue

Right on queue we get a full page spread from the Herald about traffic queues.

Wet weather, a serious crash and the post-Christmas rush combined to bring bumper-to-bumper congestion on long sections of highways and travel misery to holidaymakers.

Police described some traffic as a “rolling carpark” and urged calm as queues of up to 20km yesterday greeted motorists escaping Auckland, in the holiday hot-spot of the Coromandel Peninsula and north of Wellington.

and

Highways north and south of Auckland were crowded as thousands left the city for their New Year holiday.

Auckland Arts Festival Trust chairwoman Victoria Carter was among those caught driving north. A frequent user of the road, she said she had never known the queue to Warkworth to be as long.

“We got to the (Johnstones Hill) tunnel at 11am and there was a queue coming out of the tunnel as we arrived at it and we were hoping it was not the queue for Warkworth … and it was.

“We crawled to Warkworth at an average speed of 15-20km/h … It looks like the congestion stemmed from the traffic lights in Warkworth.”

Transport Agency spokesman Anthony Frith said a 20km northbound queue formed on State Highway 1 to Warkworth from 10am.

Last month, the Government approved a fast-track consent process for a $760 million extension of the Northern Motorway to Warkworth.

The Transport Agency has not set a start date for the 18.5km four-lane extension from the Johnstones Hill tunnels, but construction is expected to start between 2015 and 2019 and end between 2020 and 2025.

The traffic lights at at Warkworth are definitely a problem need to be addressed but that doesn’t mean it needs a full offline motorway to do it. The most prudent thing to do would be to build the bypass part of the project first by way of a small section of road from the existing SH1 to the P2W route as shown below. An additional small section of road to link where the bypass joins back to SH1 across to Matakana Rd would eliminate almost all through traffic out of Warkworth.

warkworth-bypass

After those two pieces of work have been completed, we could then see just what impact they would have on traffic patterns and congestion and allow us to see if a full motorway connection between Puhoi and Warkworth is really needed. If that motorway still stacks up (which I doubt it would) then very little has been lost as only the blue section in the map above (about 1.3km) would have been surplus to requirements. However depending on how it was designed, that blue link could eventually be used as a link to another interchange which would mean the project would actually be of some benefit to locals as what is currently proposed would actually be longer for locals to use than the existing road.

I’m almost certain the only reason this isn’t being pursued is that those in support of the project know it would kill what little justification there is for the rest of the project.

BTW – to someone who has a physical copy of the paper, what’s that rubbish in the top right corner with flying cars. If there were about to come on stream then wouldn’t that kill the need for many of the upgrades even more?

Cartoon history of transport

A week or so ago, in a comment on his own guest post, NCD alerted us to this cartoon which I thought was brilliant. It is from French cartoonist Jean-Jacques Sempé and is from 1962 yet still seems relevant today.

Antarctic transport policy?

Wow there’s so many bits of news I want to comment on today and I don’t have time for them all so as it kind of relates to my post this morning I’ll go with this one. In parliament today Green MP Julie Anne Genter asked Gerry Brownlee about his stance on emissions and transport. It was following this news story from TV3 where he said”

I think climate change is something that has happened always, so to simply come up and say it’s man-made is an interesting prospect

So here is the debate today

The transcript is here.

This was what I thought was the best bit.

Julie Anne Genter: Can he name one place in the world where carbon emissions have reduced or where peak congestion has reduced as a result of new motorway construction?

Hon GERRY BROWNLEE: As far as I know, I would be correct in saying—because there are no motorways there—the Antarctic.

 

Brilliant question and one that left Gerry stumped because the reality is there isn’t anywhere that has built its way out of traffic congestion or emissions. Although perhaps Brownlee suggested it because in his mind hell would have to freeze over before he would accept that urban motorways don’t solve emission and congestion issues.

TomTom’s Congestion Index Report

TomTom have released their annual congestion rankings and reported that Auckland is the 17th most congested city in the world.

The City of Sails is fast becoming the City of Snails, and is rising on a list of the world’s most congested cities compiled by navigation firm TomTom.

The report, which compares congestion levels in 169 cities across six continents, found New Zealand cities were experiencing some of the biggest increases in congestion.

On the list of the most congested cities, Auckland is ranked 15th, Christchurch 17th and Wellington 37th.

New Zealanders now spend a staggering 101 hours annually in peak-hour traffic, with Auckland having the biggest increase in congestion across Australia and New Zealand.

The congestion level for Auckland is measured at 34 per cent in the last June quarter, up from 30 per cent the year before. In Christchurch and Wellington it is 32 per cent and 28 per cent respectively.

At its worst, Aucklanders are stuck in traffic for an average of 47 minutes for each hour driven.

That all sounds pretty bad but is it really? First it pays to look at how they calculate the congestion index. The reports – which can be found here  – state that it is calculated as:

With the publication of the TomTom Traffic Index we are aiming to provide the general public, industry and policy makers with unique and unbiased information about congestion levels in urban areas.

The methodology that is used in this report compares the travel times during non-congested periods (free flow) with travel times in peak hours. The difference is expressed as a percentage increase in travel time. We take into account local roads, arterials and highways. All data is based on actual GPS based measurements for each city the sample size is expressed in total number of measured miles for the period.

Straight away there is a major issue with this methodology and that is the comparison is based in just how fast you can travel if no one else was on the road compared to what happens at the during the peak period. This is a serious issue for a few reasons.

1. Cities that have a lot of all-day congestion won’t appear as bad on the report because there is less of a difference between free flow and congested periods.

2. Many of our roads have been built to try and handle peak congestion periods and are relatively empty off peak allowing for much faster speeds. The motorways are a great example as they are often bursting at the seams during the peak but can be comparatively empty off peak allowing for much much faster journeys. The Northwestern motorway is perhaps the prime example of this and is now going through another round of widening.

3. The biggest issue though is that by comparing travel times by in this manner, it ignores what the most efficient speed for moving vehicles is. By that I mean over the same stretch of road more people overall can be moved if they are travelling slow than if they are travelling 100km/h. This is something that was picked up strongly in the research conducted for the NZTA by Ian Wallis and Associates which looked at the cost of congestion. They noted the differences between the definitions of congestion as:

Various definitions of congestion were reviewed and it was found that the concept of congestion is surprisingly ill-defined. A definition commonly used by economists treats all interactions between vehicles as congestion, while a common engineering definition is based on levels of service and recognises congestion only when the road is operating near or in excess of capacity. A definition of congestion based on the road capacity (ie the maximum sustainable flow) was adopted. The costs of congestion on this basis are derived from the difference between the observed travel times and estimated travel times when the road is operating at capacity.

The graph below shows the engineering definition mentioned above.

speed-flow

4. The TomTom report misses one key aspect and that is the ability of people to travel congestion free. Investments in the rail network, Northern busway and even just some of the bus lane network in the old Auckland City Council area have led to dramatic rises in the number of people using Public Transport. In the case of the busway, it has seen the number of people crossing the harbour bridge increase from 18% in 2004 to 41% in 2011. These people are travelling almost completely free of congestion (with the notable exception of in the city centre) yet the amount of time they spend on their commute isn’t captured by this data at all because they are almost certainly not carrying a TomTom with them.

bus-trips

Instead of being a congestion index report, what the report really should be called is a private vehicle travel time variability report.

I do note some interesting responses in the articles about the report. In the herald we get

The New Zealand Transport Agency said it was working to improve traffic flow in cities through investment in public transport services and infrastructure, roading and facilities.

“Our investment in public transport is at unprecedented levels, having risen by over 20 per cent nationwide in just three years,” said agency spokesman Anthony Frith.

“We’re also investing in walking and cycling facilities that will get people out of their cars and onto their bikes or travelling by foot.”

In Auckland, the agency was investing $3.4 billion in the region’s transport system, including $1.6 billion for state highways, $968 million for roads and $890 million for public transport.

Well most of the increase in costs for PT are to pay for the NZTA’s share of the loan for the new electric trains. I’m not saying that isn’t welcome but not necessarily the massive investment suggested. Further a small fraction of that is going towards PT infrastructure.

And from Stuff:

Automobile Association principal infrastructure adviser Barney Irvine said a focus needed to be put on getting more out of the existing network.

“Public transport is an important part of the puzzle but it is only one part.

“The big thing is to try and get more out of the existing network.”

Mr Frith said several initiatives were in place to try to ease congestion in all of the cities.

Auckland had a $3.4b programme of investment in the region’s transport system from 2012 to 2015. This included improvements to state highways, local roads and public transport.

I agree that we need to get more out of the existing network and it’s good to see the AA acknowledging that.

Lastly if we really want to move people around then then the Congestion Free Network would allow people to do that completely free of congestion giving some real choice.

CFN 2030A