Is increasing population density the solution to the land-squeeze in successful cities?

Manchester. Could get some more people in there. Image: Getty.

The Centre for Cities' recent City Space Race report highlights a dilemma that most growing cities are currently facing: they need to build more houses and offices, but regulations and local political pressures restrict them from expanding, particularly when it comes to green belt development.

In theory, there is a simple way for cities to have their cake and eat it too. Increasing density — allowing taller buildings on the same space — should enable cities to provide more property space without having to expand outwards.

This idea is often the source of heated debate in public discussions about tackling the housing crisis in our most economically vibrant cities. But is increasing density the right solution for cities with high demand for land – and how viable is it in practice?

High average, low extremes

The UK is already a dense country. It has one of the highest average built-up densities — the population density of inhabited areas — across European countries.

But average national density is a blunt measurement of population versus land in a country and offers little insight into the variations across and within cities. When we look closer at UK cities, it’s clear that few urban neighbourhoods have the level of density found in other European cities. The densest square kilometre in the country, with a population of 20,000, is in the London neighbourhood of Maida Vale — an affluent area which doesn’t exactly fit the stereotype of an urban jungle.

In contrast, some urban areas on the continent exceed 50,000 inhabitants — for instance, the most populated square kilometre in Europe is in Barcelona with 53,000 inhabitants.

The chart below plots all square kilometre units that are populated with more than 10,000 inhabitants for a selection of countries. In the UK, 86 per cent of these areas have between 10,000 and 15,000 inhabitants, and the other 18 per cent have less than 20,000. By comparison, all other main European countries have areas exceeding 20,000 inhabitants, with Italy, France and Spain having a considerable share of very high-density neighbourhoods.

Source: Eurostat.

The benefits of population density

This means there is scope to increase density in UK cities, and in particular in residential neighbourhoods. This would have many benefits: not only would it allow cities to accommodate new residents without expanding, it would also improve cities’ transport accessibility and planning.

Let’s focus on this last point. Transport systems in denser cities are likely to be more efficient because they can reach a larger share of the population at lower costs. Consider Hong Kong, an extreme case of dense population settlement. Only 7 per cent of the working population commutes using their private car according to the Hong Kong statistics department.

In contrast, 33 per cent of Londoners travel to work by car (still a reasonable figure against international standards), while this group is bigger still in Liverpool (57 per cent of commuters), Manchester and Birmingham (64 per cent), as shown on our data tool.

High density in Hong Kong makes the transport network more efficient too: the metro network is short in length (210 km), and yet it serves 1.1m workers every day. In comparison, “only” 800,000 commuters use the London Underground, according to the 2011 census, despite the network being twice as long (402 km).

In other words, denser cities lead to better transport accessibility, and this, in turn, means better access to jobs, less traffic congestion and fewer carbon emissions. (As research by LSE cities shows, there is a clear negative correlation between urban population density and carbon emission per capita.)

The challenges of increasing density

As such, increasing population density clearly brings significant advantages. However, it is not easy to achieve, and there are two main reasons for this.

First, some local residents are concerned that densification will alter and threaten the nature and shape of their city, and this puts political pressure on councils not to act. That’s because densification is often amalgamated with high-rise buildings.

 But London does not have to become Hong Kong. If only 5 per cent of the capital’s built up area had the density of Maida Vale, it could host an additional 1.2m people, without the need to expand outwards.

Second, it is easy to forget the administrative and technical complexities of densification. In concrete terms — both literally and figuratively — densification means knocking down existing buildings to build new ones. This is time-consuming and it has a cost. Moreover, unless a city has in place an overarching plan to increase densification across its length and breadth, it will take decades for it to become more compact.


What should be done?

For growing cities to build more houses and commercial space, there are only two options: build up or build out.

Building up (densification) has many great benefits, but it is also difficult to deliver. To have a chance to happen, densification must be at the core of strategic planning policies and cities must have the necessary power, determination and leadership to bring it about. However, this is a long-term strategy, with benefits that will only be reaped in the long-term.

In the meantime, a number of cities have an urgent need to build more houses, and lack of action puts pressure on the existing stock, as highlighted in our report. Only building out (expanding) will enable them to respond to this need quickly enough. In most cases, this means that some green belt land must be released for development.

This is a difficult trade-off, but there is a middle ground between full densification and full expansion. For instance, cities could release plots of green belt land that are found within walking distance to an existing train station, and ensure that new developments have higher densities (in a Maida Vale rather than a Hong Kong style). This would allow cities to create a large number of homes on a small fraction of the land, limiting encroachment on the green belt and allowing easy transport access to the city.

Hugo Bessis is a researcher for the Centre for Cities, on whose blog this article originally appeared.

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What are Europe’s longest train journeys?

The Orient Express was a pretty long train. Image: Getty.

For reasons that aren’t clear even to me, a question popped into my head and refused to leave: what’s longer? Britain’s longest train joruney, or Germany’s?

On the one hand, Germany is quite a bit larger – its area is 70 per cent more than Great Britain’s. On the other hand, Great Britain is long, skinny island and Germany is much rounder – the distance from John O’ Groats to Lands End is over 1,400 km, but you never have walk over 1,000 km to cross Germany in any direction.

And it turns out these factors balance almost each other out. Britain’s longest train, the CrossCountry from Aberdeen in Scotland to Penzance in Cornwall, runs 785 miles or 1,263 km. Germany’s longest train, the IC 2216 from Offenburg in the Black Forest to Greifswald on the Baltic coast, is exactly 1,300 km. Germany wins by a tiny distance.

Except then I was hooked. What about the longest train in France? Spain? Italy?

So I did what anyone would do. I made a map.

The map above was all drawn with the Deutsche Bahn (Germany Railways) travel planning tool, which rather incredibly has nearly every railway in Europe. The data quality is better for some countries than others (the lines in France aren’t quite that straight in real life), and the measurements may be a bit off – it’s not always easy to find the length of a train service, especially when routes can vary over the year – but it gives us a good idea of what the routes look like.

Let’s start with the UK. The Aberdeen to Penzance route isn’t really for people who want to go all the way across the country. Instead, it’s a way to link together several railway lines and connect some medium-to-large cities that otherwise don’t have many direct services. “Cross-country” trains like these have existed for a century, but because they crossed multiple different company’s lines – and later, multiple British Rail regions – they tended to get ignored.

 

That’s why, when it privatised the railways, the government created a specific CrossCountry franchise so there was a company dedicated to these underused routes. If you want to get from Edinburgh to Leeds or Derby to Bristol, you’ll probably want a CrossCountry train.

The usual route is Edinburgh to Plymouth, but once a day they run an extra long one. Just one way though – there’s no Penzance to Aberdeen train. 

The longest train in Germany is weird – at 1,400 km, it’s substantially longer than the country itself. On the map, the reason is obvious – it takes a huge C shaped route. (It also doubles back on itself at one point in order to reach Stuttgart).

This route takes it down the Rhine, the biggest river in west Germany, and through the most densely populated patch of the country around Cologne and Dusseldorf known as the Ruhr. Germany’s second and third longest trains also have quite similar routes – they start and end in remote corners of the country, but all three have the Rhine-Ruhr metropolitan area in the middle.

You’re not meant to take the IC 2216 all the way from north east to south west – there are much more direct options available. Instead, it’s for people who want to travel to these major cities. They could run two separate trains – say, Offenburg-Dusseldorf and Griefswald-Cologne – but making it a single route means passengers benefit from a bit more flexibility and helps DB use its rolling stock more effectively.

France’s longest train exists for a very good reason. Most of France’s high-speed lines radiate out from Paris, and it’s very hard to get around the country without going to the capital. Usually to get from Marseille on the Mediterranean to Nantes near the Atlantic, you’d need to take a TGV to Paris Gare de Lyon station, then get the Métro across the city to Gare Montparnasse.

Once a day though, this TGV avoids this faff by stopping in the suburb of Juvisy and turning around without going into the centre. This lets passengers travel direct between the coasts and reduces the traffic through Paris’s terminals in the rush hour. The exact length of this route isn’t clear, but Wikipedia says it’s about 1,130 km.

Spain’s longest train is very different. This is the Trenhotel sleeper service from Barcelona to Vigo, and it’s pretty fancy. This is a train for tourists and business travellers, with some quite luxurious sleeping cabins. But it is a regularly scheduled train run by the state operator Renfe, not a luxury charter, and it does appear in the timetables.

Being dry, hot and quite mountainous in its middle, most of Spain’s cities are on its coast (Madrid is the one major exception) and as a result the train passes through relatively few urban areas. (Zaragoza, Spain’s 5th largest city, is on the route, but after that the next biggest city is Burgos, its 35th largest,) This is partly why overnight trains work so well on the route – without many stops in the middle, most passengers can just sleep right through the journey, although there are occasional day time trains on that route too if you want to savour the view on that 1,314 km journey.

Finally, there’s Italy. This is another sleeper train, from Milan in the north to Syracuse on the island of Sicily. It goes via Rome and travels along the west coast of... wait, it’s a train to the island of Sicily? How, when there’s no bridge?

Well, this train takes a boat. I don’t really have anything else to add here. It’s just a train that they literally drive onto a ferry, sail across the water, and then drive off again at the other side. That’s pretty cool.

(As I was writing this, someone on Twitter got in touch to tell me the route will get even longer in September when the line to Palermo reopens. That should be exciting.)

So those are the longest trains in each country. But they aren’t the longest in Europe.

For one thing, there are some countries we haven’t looked at yet with very long trains. Sweden has some spectacular routes from its southern tip up into the Arctic north, and although the Donbass War appears to have cut Ukraine’s Uzhorod to Luhansk service short, even Uzhorod to Kharkiv is over 1,400 km. And then there are the international routes.

To encourage the Russian rich to take the train for their holiday, Russian Railways now run a luxury sleeper from Moscow to Nice, passing through France, Monaco, Italy, Austria, Czechia, Poland, Belarus and Russia. This monster line is 3,315 km long and stretches across most of the continent. That’s got to be the longest in Europe, right?

Nope. Incredibly, the longest train in Europe doesn’t actually cross a single border. Unsurprisingly, it’s in Russia, but it’s not the Trans-Siberian – the vast majority of that’s route is in Asia, not Europe. No, if you really want a long European train journey, head to Adler, just south of the Olympic host city Sochi. From there, you can catch a train up to Vorkuta on the edge of the Arctic Circle. The route zigzags a bit over its 89 hour, 4,200 km journey, but it always stays on the European side of the Ural mountains.

Bring a good book.

Stephen Jorgenson-Murray often tweets about this kind of nonsense at @stejormur.


All maps courtesy of Deutsche Bahn.