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2.2. Level City

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(Weitergeleitet von Level City)

Within the Polycentric Region, create variations in density, but following a relatively continuous building volume.


Level City
Level City


Problem-statement: Evidence indicates that one of the most optimal urban forms is a relatively continuous building volume with a height of between two and ten stories — what we may refer to as the “level city”. Yet in the last half-century, many cities have taken on a discontinuous and disruptive form, with significant long-term negative impacts on the quality and resource efficiency of city life.


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Discussion:: Many people assume that in order to achieve a compact, sustainable and prosperous city, it is necessary to “go up” — that is, to adopt an urban form that includes many tall buildings. The evidence shows that this view is mistaken — and it overlooks research on the many negative impacts of tall buildings, especially in the longer term.¹


First, let us acknowledge that, for many people today, this pattern may be one of the most surprising and perhaps controversial in this collection. The practice of building tall is so widespread, and the assumptions about its benefits are so widely shared, that the actual evidence may come as a shock. However, let us consider the evidence carefully — for the impacts in the future are potentially enormous.


Some advantages of tall buildings are obvious: they offer very nice views (when not blocked by other tall buildings), they confer status and prestige, and they create very visible branding for companies and for ego-centered individuals. But many other commonly claimed benefits of tall buildings are contradicted by the evidence, as our research and others’ has shown.² (See also Four-Story Limit, APL 21.)


Among the more spurious claims are that tall buildings, by adding housing units, will help to promote affordable housing — yet they count among the most expensive construction systems in the world, particularly given costs associated with structural stiffening, egress requirements (space devoted to stair and elevator cores), and other diseconomies. No less dubious is the claim that tall buildings can be inherently more sustainable, given their high embodied energy and materials, greater exposure to heat gain and loss, and typically high-maintenance, short-life-cycle mechanical systems, requiring frequent and resource-intensive overhauls.

In fact many of these claims rely on a deeper misconception, that tall buildings are necessary to achieve beneficially higher densities. But there is abundant evidence to disprove this fallacy as well. As a UK House of Commons fact-finding report concluded, tall buildings “do not necessarily achieve higher densities than mid or low-rise development and in some cases are a less-efficient use of space than alternatives... Tall buildings are more often about power, prestige, status and aesthetics than efficient development.”3


Level City
Level City
Three very different urban forms at very different heights — yet they all achieve precisely the same density. Many people fail to understand that tall buildings are commonly placed very irregularly, typically between large unwalkable areas of green space, parking lots, or low buildings, with little or no net increase in density over other possible forms. Source: UK Urban Design Task Force, 1999.


The research also shows that there are many other negative impacts of tall buildings, including environmental impacts on adjacent buildings and public spaces (shading, loss of views, wind effects, loss of human-scale experience); social impacts (“vertical gated communities,” loss of ground-floor activation, etc), and economic impacts (increased maintenance costs over time, obsolescence of design fashions, threat of market failures and abandoned buildings, etc).⁴


Perhaps the most alarming evidence against residential tall buildings is recent evidence of psychological impacts, most severely in children. Negative effects include higher levels of depression and anti-social behavior, and marked impairment of child development.⁵


Tall buildings do indeed allow some people and companies to achieve literal superiority over the city, expressing their social and economic dominance. At some point, however, this concentration of wealth is likely to prove unhealthy, exacerbating inequality and instability. A “level city” (maintained by zoning codes, incentives and disincentives, or a mix) offers a more “level playing field” — a more equitable and more evenly distributed kind of urbanism.


This is not to say that higher density is not desirable — or, at the other extreme, that a very high density is always required. In fact the best cities offer a range of densities, tending to increase toward their regional centers, but containing many variations or “density rings” throughout the region. For example, a “polycentric region” will contain many density rings of lower and higher densities, offering choices corresponding to stages of life (children, couples, singles, elderly etc.) and preferences (active centers, quieter backs, etc.).


Finally, it is important to note that there is an important role for some tall buildings to serve as wayfinding landmarks, and as monuments to the city’s public life. These structures should be exceptional, and they should be civic in nature — for example, spires within public spaces, like the Eiffel Tower in Paris, or structures that express a shared spiritual experience, like the Sagrada Familia cathedral in Barcelona (seen in the photo at the beginning of this pattern).


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Therefore:

Maintain a building height limit of typically no more than ten stories, together with incentives for maximizing infill of buildable sites, aiming to produce a continuous and efficient urban form. Allow taller structures when they are civic monuments and public buildings, and when they assist with wayfinding. Allow variations in density, while assuring a continuous walkable urban fabric.


Level City
Level City


Use the pattern Perimeter Building to maximize continuous fabric along the street. Cluster each group of housing and other activities within a Density Ring. Use a Form-Based Code to provide for coherent massing with extra height only where appropriate…


Use the pattern Perimeter Building to maximize continuous fabric along the street. Cluster each group of housing and other activities within a Density Ring. Use a Form-Based Code to provide for coherent massing with extra height only where appropriate…




¹ See for example Alterman, R. and Mehaffy, M. (2019). Tall Buildings Reconsidered: The Growing Evidence of a Looming Urban Crisis. Working Paper, Centre for the Future of Places. Available on the Web at http://sustasis.net/TallBuildings.pdf.


² Our colleague Patrick Condon has described a similar argument in work on what he calls “The Flat City”. See Jing, H., & Condon, P. M. (2018). Flat City: Development Trend of World Cities Under the Influence of Digital Communication Technology Progress and Its Enlightenment to China. Urban Planning International, (2), 8.


³ See UK House of Commons (2002), Sixteenth Report of Session 2001-2002. London: UK Parliament Publications. Available on the Web at https://publications.parliament.uk/pa/cm200102/cmselect/cmtlgr/482/482.pdf.


⁴ Our colleague Rachelle Alterman has done notable work in this area. See for example Alterman, Rachelle (2009). Failed Towers: The condominium maintenance conundrum. Haifa: Center for Urban and Regional Studies, Technion — Israel Institute of Technology.


⁵ See for example the research collection by Boys Smith, N. (2016), Heart in the Right Street: Beauty, happiness and health in designing the modern city. London: Create Streets.




SECTION I:

PATTERNS OF SCALE


1. REGIONAL PATTERNS

Define the large-scale spatial organization…

1.1. POLYCENTRIC REGION

1.2. BLUE-GREEN NETWORK

1.3. MOBILITY CORRIDOR

1.4. 400M THROUGH STREET NETWORK

2. URBAN PATTERNS

Establish essential urban characteristics…

2.1. WALKABLE MULTI-MOBILITY

2.2. LEVEL CITY

2.3. PUBLIC SPACE SYSTEM

2.4. BIOPHILIC URBANISM

3. STREET PATTERNS

Identify and allocate street types…

3.1.URBAN GREENWAY

3.2. MULTI-WAY BOULEVARD

3.3. AVENUE

3.4. SHARED SPACE LANE

4. NEIGHBORHOOD PATTERNS

Define neighborhood-scale elements…

4.1. STREET AS CENTER

4.2. PEDESTRIAN SANCTUARY

4.3. NEIGHBORHOOD SQUARE

4.4. NEIGHBORHOOD PARK

5. SPECIAL USE PATTERNS

Integrate unique urban elements with care…

5.1. SCHOOL CAMPUS

5.2. MARKET CENTER

5.3. INDUSTRIAL AREA

5.4. HOSPITAL

6. PUBLIC SPACE PATTERNS

Establish the character of the crucial public realm…

6.1. PLACE NETWORK

6.2. WALKABLE STREETSCAPE

6.3. MOVABLE SEATING

6.4. CAPILLARY PATHWAY

7. BLOCK AND PLOT PATTERNS

Lay out the detailed structure of property lines…

7.1. SMALL BLOCKS

7.2. PERIMETER BLOCK

7.3. SMALL PLOTS

7.4. MID-BLOCK ALLEY

8. STREETSCAPE PATTERNS

Configure the street as a welcoming place…

8.1. STREET AS ROOM

8.2. TERMINATED VISTA

8.3. STREET TREES

8.4. STREET FURNISHINGS

9. BUILDING PATTERNS

Lay out appropriate urban buildings…

9.1. PERIMETER BUILDING

9.2. ARCADE BUILDING

9.3. COURTYARD BUILDING

9.4. ROW BUILDING

10. BUILDING EDGE PATTERNS

Create interior and exterior connectivity…

10.1. INDOOR-OUTDOOR AMBIGUITY

10.2. CIRCULATION NETWORK

10.3. LAYERED ZONES

10.4. PASSAGEWAY VIEW



SECTION II:

PATTERNS OF MULTIPLE SCALE


11. GEOMETRIC PATTERNS

Build in coherent geometries at all scales…

11.1. LOCAL SYMMETRY

11.2. SMALL GROUPS OF ELEMENTS

11.3. FRACTAL PATTERN

11.4. FRAMING

12. AFFORDANCE PATTERNS

Build in user capacity to shape the environment…

12.1. HANDLES

12.2. CO-PRODUCTION

12.3. FRIENDLY SURFACES

12.4. MALLEABILITY

13. RETROFIT PATTERNS

Revitalize and improve existing urban assets …

13.1. SLUM UPGRADE

13.2. SPRAWL RETROFIT

13.3. URBAN REGENERATION

13.4. URBAN CONSOLIDATION

14. INFORMAL GROWTH PATTERNS

Accommodate “bottom-up” urban growth…

14.1. LAND TENURE

14.2. UTILITIES FIRST

14.3. DATA WITH THE PEOPLE

14.4. INCREMENTAL SELF-BUILD

15. CONSTRUCTION PATTERNS

Use the building process to enrich the result…

15.1. DESIGN-BUILD ADAPTATION

15.2. HUMAN-SCALE DETAIL

15.3. CONSTRUCTION ORNAMENT

15.4. COMPLEX MATERIALS



SECTION III:

PATTERNS OF PROCESS


16. IMPLEMENTATION TOOL PATTERNS

Use tools to achieve successful results…

16.1. FORM-BASED CODE

16.2. ENTITLEMENT STREAMLINING

16.3. NEIGHBORHOOD PLANNING CENTER

16.4. COMMUNITY MOCKUP

17. PROJECT ECONOMICS PATTERNS

Create flows of money that support urban quality…

17.1. TAX-INCREMENT FINANCING

17.2. LAND VALUE CAPTURE

17.3. EXTERNALITY VALUATION

17.4. ECONOMIES OF PLACE AND DIFFERENTIATION

18. PLACE GOVERNANCE PATTERNS

Processes for making and managing places…

18.1. SUBSIDIARITY

18.2. POLYCENTRIC GOVERNANCE

18.3. PUBLIC-PRIVATE PLACE MANAGEMENT

18.4. INFORMAL STEWARDSHIP

19. AFFORDABILITY PATTERNS

Build in affordability for all incomes…

19.1. INTEGRATED AFFORDABILITY

19.2. COMMUNITY LAND TRUST

19.3. MULTI-FAMILY INFILL

19.4. SPECULATION TAX

20. NEW TECHNOLOGY PATTERNS

Integrate new systems without damaging old ones…

20.1. SMART AV SYSTEM

20.2. RESPONSIVE TRANSPORTATION NETWORK COMPANY

20.3. AUGMENTED REALITY DESIGN

20.4. CITIZEN DATA