What is a city, anyway?

This, believe it or not, is London. Image by Tom Tired of London

Okay, there's a question we're going to be wrestling with a lot at CityMetric. I'm not saying we're going to answer it any time soon, but the least we can do is ask it, and explain why it constitutes a problem. Here it is:

What, actually, is a city?

At first glance this probably looks like a stupid question, the sort of thing you'd get from a four year old, like "What are unicorns made of?" or “Why is the sky blue?” But (spoilers) it's not.

To explain why, it helps to have a worked example or two. London, official figures tell us, has a population of somewhere around the 8.3 million mark. Paris has a population of roughly 2.3 million. So, one might naturally conclude, London is a lot bigger than Paris.

Except, if you look at a different set of figures, it's very clearly not.  Demographia has been publishing a statistical guide to the World's Urban Areas for a decade or so now. Its latest edition, published in May, has Paris on 11 million – four times larger than the official statistics and well ahead of London's 10.1 million.

Then you look at this dataset from the official statistical agency of the European Union and the figures get even bigger but the order's swapped again. Eurostat has Paris on 11.9 million and London on 13.6 million.

You don't have to be a geographer to guess that these three sets of figures are working from different definitions. You can probably even make an educated stab at what each set of figures represents. They are, respectively, the population of the region governed by the city's own authorities, of the continuous built up area, and of the larger metropolitan region.


But which of these is ‘right’? The answer is, infuriatingly, all of them – or, if you prefer, none of them.

To most people, most of the time, none of this is actually a problem: no one ever failed to understand the concept of London because they were unclear on whether you were counting Watford or not. But there are two contexts in which it matters a great deal.

One is its impact on the workings of city governments. If you're the official charged with coming up with a strategy for meeting an area's housing or transport needs, say, then it would help to have some control over the whole of that city.

Very often, though, you don't, so infrastructure investment is likely to focus on the city proper: not only is official power strongest there, but its population get a vote in local elections. Administrative borders can thus end up warping the fabric of the city itself. Just look at the apparently arbitrary places where the New York Subway terminates.

The other reason why which this definitional confetti matters is that it poses a massive barrier to anyone who actually hopes to analyse the urban landscape. Professor Geoffrey West is a theoretical physicist at the Santa Fe Institute, who in recent years has conducted a number of comparative studies on cities. “You'd think by now all the urban planners would have an operational definition of a city that you just could look up,” he says, with some exasperation. “Well that doesn't exist."

As a result, the moment you start trying to quantify any aspect of city life – or worse, compare two cities – you run into difficulties. How many people live in Mumbai? What's the size of New York's economy? Which is more densely populated, London or Paris? All too often, the answer is ‘it depends’. "It's a problem that's plagued a lot of our research," West adds. "And it reflects how little work has been done to quantitatively, analytically, and scientifically understand cities."

The upshot of all this is that what a city is, and where it ends, is a surprisingly subjective matter, and any attempt to nail it down is likely to throw up anomalies. All you can do is keep track of which definition you're working from, and make sure you never, ever, compare apples with larger urban zones.

Here, for future reference, is a quick guide to the main ways of defining cities, which we’ll be trying very hard not to mix up.

 

The municipality

The political definition of a city. Paris is 20 arrondissements, New York is five boroughs, London is 32-plus- that-awkward-finance-y-bit-in-the-middle.

The advantage of this definition is that it’s nice and straightforward and easy to exert political power over (or find data on, come to that). The disadvantage is that it tends to throw up anomalies: some municipalities exclude large swathes of suburbia; others include sudden patches of countryside. The official definition of London includes North Ockendon, a tiny Essex village outside the M25, but excludes Buckhurst Hill, a contiguous central line suburb well inside it.

 

The urban area

This, one might think, is the contiguous urban sprawl: the thing you can point to on a satellite photograph, or from a plane by night.

Life, though, is rarely so simple. For one thing, areas of development separated by less than 200m of open space will generally be bracketed together as a single urban area, on the grounds that anything you can cross in under two minutes doesn’t count as ‘the country’.

For another, there are features like parkland and forests to contend with, so sometimes you’ll notice a distinction between ‘urban area’ (which includes suburban open spaces) and ‘built up’ area (which doesn’t).

There is also no single universal definition of what counts as an ‘urban area’. Most countries define it as one with at least 400 inhabitants per square kilometre. In the US it’s 1,000 people per square mile, which is nearly identical; in Australia, it’s 200 people per square kilometre, which isn’t.

 

The metropolitan area

A city's effective economic footprint, typically measured by commuting patterns. Satellite towns and ex-urbs may not look like part of a city – but since they wouldn’t exist without it, the thinking goes, they should count.

There are two problems with this idea, however. The smaller one is that you end up counting a lot of people who reject the idea they live in a city at all, if only because they made a conscious decision not to (hello, Surrey).

The bigger problem is that it's largely subjective. What proportion of people need to commute into a city to be part of its travel-to-work area is a matter of judgement. And what if a town between two cities contains large numbers of people who commute to both? Is Warrington a satellite of Manchester, or one of Liverpool? Does Princeton belong to New York or Philly?

The consequence of all this is that different countries use different definitions. While agencies like Eurostat have attempted to harmonise these, there's no current data set that does so worldwide.

Here’s an example of all these various definitions at work. This is Paris, c2008:

That tiny maroon nucleus is the city proper. Surrounding it you have the larger built up area (red), the official urban area (orange) and the metropolitan area (yellow). Suddenly, you can understand why the figures for the city’s population seem to vary by a factor of four. 

 

Just to make things more complicated...

While a metropolitan area will typically contain more than one urban area, the same can be true in reverse. Look down from an aeroplane, and you might think that San Diego and Tijuana are a single city. But there’s a whopping great international border between the two, which most of the area’s population aren’t free to cross. So is it one city, or several? How do you define them? As ever, the answer, awkwardly, is “it depends”.

 

Lastly, some definitions we won’t be using

The bizarre official phenomenon of British city status, an honorific handed out by the queen, which means that Ely (pop: 20,000) and St David’s (pop: 2,000) have the same official status as Manchester. The equally bizarre habit in some parts of the US, of appending the word ‘city’ to any cluster of four broken down sheds and a dog. What of these, eh?

Well, these are silly and we intend to ignore them. So there.

Images: Photo of Pratt's Bottom courtesy of Tom Tired of London, taken from Flickr under a creative commons license; map of Paris adapted from Wikimedia Commons.


 

 
 
 
 

Why is it acceptable to kill someone? On the mysterious history of Britain’s road death toll

A London speed camera, 2004. Image: Getty.

A decade ago I became fascinated by a graph. This one:

I had been tracking the underlining data for years. The figures were easy to remember. Every year it was 3,500, plus or minus a percentage point or two.

Yet when the 2008 data was released, it had fallen to 2,538. This was 1,000 less than the figure in 2003. I plotted the above graph, and as I said, I became fascinated.

Because this is a really important graph. This is a plot of the number of people killed on Britain’s roads each year.

In Great Britain, collectively, we used to kill nearly 3,500 people on our roads every year. Consistently or, dare I say it, boringly: 3,500 deaths a year, 10 a day. It was accepted, in a, “Well yes it’s bad, but what can you do about it” kind of way. There was no clamour for change. Newspapers weren’t running headlines about the deaths mounting up, as they do with knife crime.

Meanwhile a train crash would be front page news for a week. Take the train that derailed at Hatfield on 17 October 2000, a tragedy in which 4 people died. That led to huge media interest, massive upheaval on the railways, and, ultimately, as the re-nationalisation of Railtrack, whose failings had caused the crash. Yet more than twice as many people will have died on the roads that day. Nothing was written about those deaths. Nothing changed.

In 2000, four people died in train crashes, while 3,409 died on the roads.

Here are those figures again.

1997 – 3,599 people killed on our roads

1998 – 3,422

1999 – 3,423

2000 – 3,409

2001 – 3,450

2002 – 3,431

2003 – 3508

But, in 2004 the figure dropped below 3,400 for the first time, to 3,221. Then in 2005 to 3,201.

2006 – 3,172

2007 – 2,946

Below 3,000! This was change. Significant change: 500 lives a year were not being lost. If you use Britain’s roads, your life may have been one of them.

2008 – 2,538

2009 – 2,222

When the 2010 figures came out I was amazed by the headline figure: 1,857.

That’s still far too high, of course, but it was 1,701 lower than seven years earlier.

This was a major story that deserved a ton of coverage, which it failed to get. Having shown no concern for when we were killing 3,500 people, it wasn’t overly surprising that the fact we were now killing 1,700 fewer wasn’t celebrated.

At any rate, the graph had flat-lined for years, then, in half a dozen years, it halved. Why?

The lack of media coverage resulted in an absence of answers. One commentator, Christian Woolmar, observed that there was no clear answer to why this had happened. But he went on to point out that there had been a fall in the average road speed over this period.

My anticipation of the 2011 figures troubled me, because I expected them to go up. Obviously I didn’t want them to: I desperately want zero deaths on our roads. But something happened in 2010 that I was sure would lead to more fatalities and bring a halt to the falling trend.

I was right. In 2011 we killed 1,901.

Sometimes, being right is shit.

The news was better in 2012. The fatality rate was 1,754. So was the 2011 figure just a blip, due to some significant snowfalls that year? No: the trend was over.

The number of people killed on our roads has remained stuck in the 17 hundreds. 

2013 – 1,713

2014 – 1,775

2015 – 1,732

2016 – 1,792

2017 – 1,793

2018 – 1,782

We have returned to a flatline on the graph – and if anything, I’m more fascinated now than I was before. Road deaths flatlined at 3,500 for years, then fell sharply, then flatlined again at half the rate.

This can’t have happened by accident. I wished I could explain it. I wish we could repeat it. No: I wish the second flatline hadn’t happened, and the fall had continued. If the rate of fall had continued, we’d have reached zero deaths on the road by now. You’d be right to question whether this is possible – but if you can half the number in a few years, why can’t we eradicate them altogether? The railways are an example of what is possible. The last time a passenger died in a train crash on Britain’s railways was in 2007.

It was time to figure out the answers to two questions. Why did the death toll fall? And why did it stop falling?

The obvious reason for a reduction in deaths on the road is the improvement in car safety features. This could create a gradual fall in the death toll as new, safer cars replaced older ones. But I’m not sure it can explain a 40 per cent fall over a 4 year period.

There’s a way to check whether cars on the road became almost twice as safe between 2003 and 2010: you can compare the figures with the rest of the EU. Car safety features are international, and any new feature would have appeared around the same time across the continent.

So I found the EU figures for 2000 to 2017, indexed for 2000 and plotted the graph for multiple countries. It was a busy graph. For clarity the following graph only includes Britain, Germany, France, Spain and Italy along with a straight line drop for comparison.

The good news is that things are improving across Europe – but no country had quite the same trajectory as Britain. They all have a fall much closer to a straight line of the sort you’d expect a general improvement in car safety would produce.

One thing I did notice is that, from 2013, these five countries stop falling. The technology based solutions of recent years, such as automatic emergency braking, don’t appear to be saving lives as of yet.

So, yes, cars are safer – but that doesn’t seem to explain why British roads suddenly became 40 per cent safer between 2006 and 2010.


In 1999, the New Labour government announced that it was going to reduce deaths on our roads. The target was a 50 per cent reduction by 2010. As you now know, it succeeded. This was a major achievement for a government. The kind of thing you would bang on about all the time. “Deaths on our roads halved by Labour!” But the party wasn’t in government when the 2010 figures were released – and it’s hard to take credit for your achievements from the opposition benches.

That it was government policy is not a full explanation, and how this happened is a little opaque. From what I can gather there was a wide ranging approach. The fire and rescue service changed their practices: because they recognised that survival rates were directly dependent on how quickly people got to hospital, this became the priority. Disturbing a police crime scene was allowed if it saved a life. Accident black spots were located, highlighted and safety measures implemented. Throughout that period road safety campaigns focused on speed, with “Speed Kills” being the dominate message for that decade. The government also changed the laws on speed cameras.

RoSPA, the Royal Society for the Prevention of Accidents, has a lot to say about speeding and speed cameras. Its “Speed Camera Factsheet” states that, “Cameras are a very effective way of persuading drivers not to speed, and thereby reducing the number of people killed and seriously injured.” It reports that an independent review published by the Department for Transport (DfT) in 2005 said that “cameras significantly reduce speeding and collisions, and cut deaths and serious injuries at camera sites”, adding that cameras sites were delivering 100 fewer deaths per year.

Cameras first appeared in 1991, and revenue from court fines and fixed penalties went to the Exchequer. However in 2000 a trial scheme saw local councils keep the fines to pay for the cost of speed and red-light cameras. The pilot was so successful that, in 2001, legislation enabled this to happen across the country. The cost of providing and operating cameras moved from the local authority to the law breaking motorist.

The golden age of the speed camera had begun.

There was a tweak to this legislation in 2007. Fines reverted back to the Exchequer’s piggy bank. The DfT switched to funding cameras through a road safety grant. The intention was to create a greater mix of road safety measures agreed between local authorities and the police.

The number of people killed on British roads in 2007: 2,946

The number of people killed on British roads in 2010: 1,857

So perhaps the creation of the Road Safety Grant had a significant impact.

The second question: why did the death toll stop falling?

In 2010 I was unaware of Labour’s target to halve deaths on the roads. But, the change in government was enough for me to predict that the fall was over.

When the Tory/Lib Dem government negotiated its way into power in May 2010, the press declared that it was the end of the horrible nanny state – a return to personal freedom, liberty and the rule of common sense.

The way that this was to play out in real practical terms was on our roads. The evil speed camera was in the firing line. The narrative was that these cameras were just there so councils could extract cash from the poor public. Completely ignored were the facts that the fines were only handed down to dangerous, law-breaking drivers, and that councils no longer got the cash from fines.

Soon after the election the coalition government said that “Labour's 13-year war on the motorist is over” and pledged to scrap public funding for speed cameras. The Road Safety Grant to local authorities was cut from £95m to £57m. This meant that the government was now receiving an estimated £40m more raised in fines than it was spending on road safety. The cut to the grant reduced the camera maintenance budget by 27 per cent. It removed all the funding for new cameras, speed humps and other safety measures.

And the golden age ended.

Councils across the country announced their change of policy. Oxfordshire County Council switched off its speed cameras on 1 August 2010. Money was saved; lives were lost.

Eight months later, on 1 April, Oxfordshire’s cameras snapped back into life when the council reversed its decision because deaths on the county’s roads had immediately increased.

Turning off speed cameras sent out the message that we were no longer taking speeding seriously. The road safety campaigns changed their focus. The message that Speed Kills fell away and was replaced by drink- and drug-driving messages. It’s easy to miss that these campaigns move from encompassing virtually every driver to targeting a minority. A switch from confronting a socially acceptable behaviour to re-enforcing something already unacceptable. The state is no longer challenging everyone to be safe – only the small minority of bad people.

Yet speed still kills. The World Health Organisation states that an increase in average speed of 1 km[h typically results in a 3 per cent higher risk of a crash involving injury, with a 4–5 per cent increase for crashes that result in fatalities.
The majority of safety measures installed before 2010 remain in place and are saving lives. But with the funding gone councils are no longer installing new measures and the death toll is no longer falling.

So you can make a strong case that the pattern of road deaths was the result of government policy.

Which begs the question of our government: why has it accepted that it’s OK to kill, or be killed, on our roads?