There’s a popular doomsday scenario where Sydney and Melbourne collapse from the intolerable burden of their populations doubling to 8 million by circa 2050. Traffic grinds to a halt and commuters take forever to get to work according to this dismal prognosis, resulting in an epidemic of social problems like increasing rates of mental illness, family breakdown, obesity and disabetes (e.g. see here, here and here).
The fear of size has lead various commentators to argue strongly for growth to be redirected to regional centres. Indeed, in the absence of a convincing environmental or equity rationale, it’s one of the fallback arguments trotted out in support of huge public subsidies for High Speed Rail.
Yet some of the world’s most productive metropolitan areas are already much bigger. London’s population is 14 million, Paris is 12 million, New York is 20 million, Chicago is 10 million, Dusseldorf is 11 million. These are also some of the most desirable places in the world to live so it’s possible their size might actually be an advantage.
As Davies observes, there are both economies and diseconomies of scale… but it’s totally possible to overcome the diseconomies:
While it’s harder to do a lot about constraints like geography or incomes, cities can take steps to aid the adjustment process. For example, as they grow they could:
- Improve mobility, by improving the efficiency of the transport system. That covers investment in new public and private transport infrastructure, as well as making better use of existing infrastructure e.g. via pricing.
- Increase accessibility, by encouraging the redevelopment of established urban areas at higher employment and residential densities.
- Facilitate adaptation, by reducing obstacles to households and firms relocating to new addresses e.g. by eliminating stamp duty liability on housing purchases (the stamp duty on a $1 million dwelling in Victoria is $55,000).
Accommodating population growth within cities makes at least as much sense as spending big on infrastructure like HSR to create sprawling dormitory suburbs in the regions. Growth is better viewed as an opportunity for our larger cities than as a problem.
One diseconomy associated with city size is increased traffic congestion. This is one of the major things that people cite as a reason to oppose development. But as Gene Maddaus writes in LA Weekly, “we know how to fix traffic, we just don’t want to“:
It’s tempting to think that traffic is one of those insoluble dilemmas of Los Angeles — just the price you pay to live in a thriving megalopolis that a lot of other people also want to live in. But the fact is that transit experts do have a pretty good idea of how to fix traffic.
There is a catch, however. The situation is sort of like that Citizen Kane quote about making a lot of money — it’s not so difficult, if that’s all you want to do. Similarly, it’s not that hard to solve traffic, if all you want to do is solve traffic.
The solution is congestion pricing. The MTA does this, on a pilot basis, on the 110 freeway south of downtown and on the 10 freeway in the San Gabriel Valley…
The tolls on the 110 and 10 “Express Lanes” range from 25 cents to $1.40 per mile. As traffic slows, the tolls go up. The goal is to maintain a minimum speed of 45 mph. (Many more details can be found here.) The idea is that putting a price on use of the freeway internalizes the external costs of driving, and forces people to make more efficient use of the freeways.
“If you don’t use price to allocate resources, other mechanisms emerge, such as queueing,” Moore says.
A traffic jam is thus little different from a Soviet-era bread line.
So now, on those segments of the 110 and the 10, drivers finally have a choice. They can pay a toll and zip along in the fast lanes, or pay with their time to use the congested, non-toll lanes.
It would be nice to have those choices in many more locations. I’ve always wondered why NZTA doesn’t have a policy of operating new motorway lanes as toll lanes – that seems like the best way to get value out of them.
And hey, this is quite interesting. A Philadelphia resident put together a comprehensive visual guide to on-street parking rules throughout the city (via Tanvi Misra at CityLab):
Lauren Ancona’s dive into cartography started with what she calls her “weird obsession” with parking—specifically, the lack of information about parking regulations in Philadelphia…
Now, after 17 months of gathering public data and manually verifying bits and pieces of information, Ancona has finally released her new and improved ‘Parkadelphia’ map. This one doesn’t just show residential parking zones, but also metered spots for cars, motorcycles and scooters, city parking lots, locations where valet parking is offered, and the emergency routes in the city.
On the map below, you can select any or all of these layers of data from the sidebar on the left, and click on a street you’re curious about. The map will then pull up the parking rules:
You can find the full interactive map here.
Speaking of maps, New Zealand just had a referendum on a new flag. Someone on Wikipedia has already put together a map showing which electorates voted for the current flag versus the alternative option:
I guess that’s the last we’ll hear of that idea for a while. If the referendum has taught me anything, it’s that New Zealanders are not really that enthusiastic about flags.
One thing that (some) people are enthusiastic about is opposing safe cycling facilities. For example, Bike Auckland reports on some rumblings of discontent on Ponsonby Road: “The future is coming – can Ponsonby Road catch up in time?”
But even knowing that their street has successfully evolved with the times, some businesses are worried about the changes posed by making the street safer and friendlier for bikes and pedestrians.
Presumably the greatest fear is around loss of car parking and of car priority. And sure, construction is never fun, and can steer some shoppers away until things settle down again. If car parks or traffic lanes are lost and nothing else replaces them but dead air or another lane of traffic, then there might well be a decline in custom. But what if you’re adding a whole new source of custom?
As merchants and shoppers discovered during a similar recent refit of a major shopping street in Salt Lake City, ‘bike lanes are typically best for business when they’re part of a general rethinking of the street to make it a more pleasant place to linger.’
In other words, bike lanes aren’t just good for cyclists – they’re part of a transformation that makes a street feel like a better place to be. They add vitality to downtrodden shopping strips currently coughing in the fumes of car traffic. They help buffer pedestrians from the constant stream of vehicles. And in conjunction with slowing traffic down, they give pedestrians better access to both sides of a street that can sometimes feel like a canyon. Double your business – now, that’s a proposition.
Frankly, I don’t really enjoy being on Ponsonby Road. While there are things to do there, I just don’t enjoy the environment. Being on the footpath stresses me out. Trying to cross the road is a pain in the neck. Even if I’ve driven there, I never want to linger for long. It’s an easy choice to head over to K Road or the downtown shared spaces instead.
Speaking of good and bad places, Jill Suttie reviews some research on the impact that being in nature has on our mood and behaviour:
Gregory Bratman, of Stanford University, has found evidence that nature may impact our mood in other ways, too.
In one 2015 study, he and his colleagues randomly assigned 60 participants to a 50-minute walk in either a natural setting (oak woodlands) or an urban setting (along a four-lane road). Before and after the walk, the participants were assessed on their emotional state and on cognitive measures, such as how well they could perform tasks requiring short-term memory. Results showed that those who walked in nature experienced less anxiety, rumination (focused attention on negative aspects of oneself), and negative affect, as well as more positive emotions, in comparison to the urban walkers. They also improved their performance on the memory tasks.
This is, in a sense, a fundamental challenge for city design. The entire point of cities is that they bring people together to allow them to collaborate and create. But if some urban environments stress us out and inhibit our creativity, they can undermine the agglomeration benefits that cities provide.
The obvious answer to this is to build street trees, public parks, etc into the city fabric as a public good… and to maintain good, accessible regional parks like the Waitakeres and Hunuas close to the city.
— Alex Armlovich (@aarmlovi) March 25, 2016
On a separate note, architect Henri Sayes and architectural writer Nicole Stock write (on The Spinoff) about the relationship between the zoning rules proposed in the Unitary Plan and the buildings that are already on the ground. It’s an interesting perspective. They highlight the convoluted nature of the rules, and also the complex nature of the existing built environment:
What has been described as unzoning is not a significant change from the current plan that was enacted in the early ’90s. The height in relation to boundary controls are more sympathetic to a well located building, but still limit over-shadowing and provide space between buildings. It’s more likely that one of the large leafy trees in these suburbs will block your sun than a neighbouring building built within the planning controls.
The vast majority of the Eastern Suburbs has not been developed with consistent, overarching controls. While you can identify stylistic themes (’60s brick and tile or ’90s plaster homes, for instance) that are consistent with the social constructs and controls of the time, when the suburb is viewed as a whole it is utterly inconstant. When people talk about the character of the Eastern Suburbs, then, they are acknowledging the success of this varied development. Start to analyse the fabric of the area and you soon realise that – despite nostalgic rhetoric implying a large house on a quarter acre section – these suburbs already have a surprising number of units, terrace houses and apartments. You also quickly realise that already a significant number of houses don’t comply with the current planning controls – but as they already exist, no one seems to mind. The unseen threat is scarier than the visible reality.
Or, as I’ve been saying for a while, status quo bias is the most powerful force in policymaking.
Lastly, the most interesting thing I’ve read all week has little to do with transport or urban policy, but statistical methods. On MedPage Today, F. Perry Wilson writes about errors in reporting hypothesis tests: “The p-value is a hoax, but here’s how to fix it“. It’s a wonderfully cogent explanation of how to apply Bayesian methods to statistical hypothesis testing:
If you think of medical research as an expression of the scientific method (a stretch, I know), you’ll see that every study has exactly four possible outcomes. I’m using drug studies as a prototypical example:
1. True Positive — the novel drug being studied was found to be efficacious and truly works. Practice changes. The world advances.
2. True Negative — the novel drug being studied was found not to be efficacious and it truly doesn’t work. Nothing changes.
3. False Negative — the novel drug being studied was found not to be efficacious but it truly works. The study was done wrong, or was underpowered or something. Nothing changes. The hope of future generations is lost.
4. False Positive — the novel drug being studied was found to be efficacious but it truly doesn’t work. The study was done wrong, or was only positive by chance. Practice changes. People get drugs that don’t work.
For me, number 4 is the most concerning. I don’t mind too much if we miss out on a potential therapy here and there, but, man, do I hate the idea of treating patients with drugs that don’t work.
But how often does #4 really happen?
The answer will shock and depress you…
Wilson explains some of the reasons why researchers commonly underestimate false positive rates, and then recommends an elegant solution:
All you have to do is assign a value to how likely you think the hypothesis is before the study was done. This corresponds to the “proportion of true hypotheses in the literature” factor above. Then, simply look at the results, combine them with your prior probability, and come out with an after-the-fact, or posterior probability.
How do you combine these things? A bit of simple math called Bayes Theorem, which I will not share with you here (thank me later). But I will give you a table of results. The following table assumes the study was “significant” at a level of P=0.05, and had 80% power.
Table 1: A positive study (ignoring fraud and bias), should always raise your estimate of the likelihood of the hypothesis being true, but you only get to that magic 5% false positive rate when your prior probability is greater than 50%.
If you look at the above table, you can see something sort of magical happens around 50% prior probability. That’s the point where a positive study moves you into a posterior probability that suggests an “acceptable” 5% false positive rate.
But think about that. When you are reading a study, if you’re less than 50/50 on whether the thing will work or not, accepting positive findings will lead to a false-positive rate that is unacceptably high.
Now, there is some hope. For one thing, sequentially positive studies can ratchet you up that ladder pretty quickly. Let’s say the hypothesis has a 10% chance of being true, but the first nice study is positive at P=0.05. Now you’re up to a 64% chance of the hypothesis being true — probably not enough to roll it out to patients unless the risk is very small, but much better. But if another study comes in that is positive at P=0.05, you’re up to a 96% chance that the hypothesis is true. See? Replication works.
That’s all for this week. Go and enjoy the rest of the long weekend – or, better yet, go find some scientific studies to replicate.