Densification is good, but doesn't require high rises

Densification is good. But does not require, and is not helped by, tower blocks.

Over the past 40 years urban planning has undergone a revolution. We now understand the high ecological cost of suburban living, the effects on people's social connectedness, and the impact on their health of long car commutes and little walking.

People are increasingly revolting against the suburban life-style. The young now find city living much more attractive, largely because the jobs are there, and also because city centres are becoming increasingly vibrant. Between 2001 and 2011 the population of large city centres in England and Wales more than doubled, with the number of residents ages 22-29 nearly tripling, to make up almost half of their population.

This calls for tighter, denser cities to support more shops and street life, with shorter commuting distances, and more walking and cycling.

Such densification will return us to something like the pattern of 19th century cities, the 'tramway pattern', a name that reflects how trams spurred the first great expansion of our cities while keeping people living near lively streets, in reach of public transport.

Source: Levitt Bernstein / Tim Crocker

Density does not require high rises. In fact most of the densest areas of European towns do not have any high rises. Europe's densest square kilometre is the centre of 19th century city of Barcelona, with 53,119 people. It is followed by Haussmann's Paris, largely built between 1853 and 1870, which is the densest city in the EU. The densest Paris kilometre has 52,218 people. Many Paris arrondissements have higher densities than Manhattan! The 11th district (42,780/km), the 3rd (31,364/km), the 20th (33,274/km), the 10th (33,000/km), the 17th (30,331/km), all the 15th (28,314/km) all out-do Manhattan (27,826/km).

Barcelona's Eixample district: very high density, no high rises

Why we should resist the developers

These sorts of high density are harder to reproduce where the city doesn't start from scratch. It requires care and good planning. That's why it is tempting for lazy city halls to surrender, and give over decision-making to developers.

In 2011 academics at Lancaster University did an online survey of 129 built environment professionals about density planning decisions. The most interesting part of the survey was the difference between those who are perceived to make the decisions, and those who should make the decisions.

Source: The Little Book of Density, Rachel Cooper and Christopher T. Boyko, Lancaster University 2012

Those who make the decisions are believed to be developers, and the local authority management officers. But they're not, in the opinion of development professionals, the best people to make the decisions! So who should make the decisions?

Source: The Little Book of Density Rachel Cooper and Christopher T. Boyko, Lancaster University 2012

Developers were seventh on the list of decision-makers who should be making density decisions, below residents. This finding suggests that developers have too much power when it comes to making decisions about the density of urban development projects, and that more emphasis should be placed on local authorities and professional designers to make those decisions.

Conclusion: densification without high rises.

"There is no question that high urban densities are important, but the question is how high, and in what form," says architect Lloyd Alter. "There is what I have called the Goldilocks density: dense enough to support vibrant main streets with retail and services for local needs, but not too high that people can't take the stairs in a pinch. Dense enough to support bike and transit infrastructure, but not so dense to need subways and huge underground parking garages. Dense enough to build a sense of community, but not so dense as to have everyone slip into anonymity."

"At the Goldilocks density, streets are a joy to walk; sun can penetrate to street level and the ground floors are often filled with cafes that spill out onto the street, where one can sit without being blown away, as often happens around towers. Yet the buildings can accommodate a lot of people: traditional Parisian districts house up to 26,000 people per sq km; Barcelona's Eixample district clocks in at an extraordinary 36,000."

"Building tall does not necessarily even increase residential density; in fact, it can do the opposite. In New York's tall, slender towers, the elevators and stairs take up a huge proportion of the floor space, and there is lot of expensive exterior wall for each unit. The construction costs for this kind of building are ridiculous, and only the very, very rich can afford to pay the price, so apartments are therefore often huge as well; consequently the population density can actually go down.

"There is less street life too, as ground floors are taken up with lobbies and exits and ramps instead of stores and restaurants. The great majority of the new projects that are busting through height limits, view corridors and historic districts do nothing to ease the housing crisis and nothing to improve the urban fabric."

Working with the community

It seems that much of Bristol Council's push towards high rises stems from the view that removing restrictions will encourage bids from developers. But this ignores the clear desires of the community, which dislikes high rises. And it ignores the fact that high rises will not bring extra housing for the less well-off.

The pressure to accommodate the housing demand in the UK is enormous. However, the opportunity is there to look more at holistic solutions. Unlike London, cities such as Bristol are not short of space; they still have capacity to accommodate the housing needed, while promoting happiness and well-being. The overwhelming evidence is that mid-rise housing in mixed-use streets is most people's preferred urban form.


Part 4: Bristol's tragedy - the trashing of a historic city