Defining public open spaces: an investigation framework to inform planning and design decision-making processes

Figures & data

Table 1. Various schools related to typology, morphology and typomorphogy: Analysis of key publications (drawings by the author, redrawn from original)

Schools	Summary of Scholl’s treatment of open spaces in analytical maps.	Representative illustration of analytical maps	Critique
German school; urban geography	Geisler (1918) No specific reference in the map key focusing on buildings Identification of military grounds including fortifications Streets and open spaces including water/canals left white Rough indication of trees	Based on Geislers map of Danzig	- Indication of non-built areas in public realm but no specification of types of open spaces - streets and urban squares left blank, only defined by the built forms represented as blocks
British school Drawing from the German tradition	Conzen (1960) Streets and squares in white with names Castle ground Boundaries of plots indicating private gardens Peripheral open spaces created before 1921 indicated in key Cleared site (urban fallow) also indicated	Based on Conzen’s map of Alnwick	- clear indication of built and non built areas in public and prviate realm - some distinction made of different types of open spaces - open spaces not analysed with same level of complex definition as the buildings
Italian school;architecture, cities and identity	Muratori et al. (1963) Streets left blank Squares in white with indication of features (fountains/sculptures) Paths/Stairs/steps indicated	Based on Muratori’s map of Rome	- The definition of open spaces is very limited in comparison to the very detailed ground floor plans of the buidlings - the indication of main features and level changes provide indication of spatial qualities
French school; multidisciplinary and practical applications	Castex, et al. (1980) Street and squares in white Indication of trees Layout of formal castle garden (parterres and water features)	Based on Castex’s map of Versailles	- main tree typologies indicated such as avenues and grove in the urban sqaure - the formal garden layout is more detailed than the built forms indentified mainly a blocks.

Figure 1. Examples of taxonomy of urban open spaces, based on shared characteristics (inspired by plant classification): (a) A taxonomy of streets (b) A taxonomy of squares

Table 2. Levels/scales of definition of urban tissue/fabric (adapted from Allain, 2004; Conzen, 1960; Kropf, 2017; Moudon, 1989, 1994)

Level of resolution	Urban environment	Urban landscape
	Wider context Natural environment Geographical location The site	Topography Hydrography Vegetation
	Urban forms Urban strategies Urban infrastructure The plan	General forms/macroform City plan Street patterns/network Block structure/city blocks Open space network
	The plot/lot structure Land tenure	Subdivision of grounds Ownership boundaries
Level of specificity	Built environment Urban spaces	Buildings Spaces between buildings (streets/squares/parks) Significant features Structural planting
	Materiality	Surfaces Colours Textures

Table 3. Key themes/parameters to assess the performance of sustainable open spaces strategies and design options (Lynch et al., 2011; Hiremath et al., 2013; science for environment policy, 2018) and relevant publications (Bentley et al., 1985; Barton et al., 1995; Jacobs, 1999; Whitford et al., 2001; Haughton & Hunter, 1994; Marshall, 2009; Carmona, 2012; Wolfrum, 2015; Lenzholzer, 2015)

Key considerations	issues	parameters	Criteria
Human comfort	Air quality/ Air pollution	Air flow CO2 absorption	Location of open spaces Type and quality of open spaces network Tree cover
	Climate change Urban heat Island	Microclimate Natural cooling	Access/proximity to open spaces and water bodies Tree cover Soft surfaces
Natural system	Water Urban rivers	Quality of water Flood mitigation	Quality of river corridors Impervious ratio Integrated water management Space for water
	Fauna and flora Loss of species	Biodiversity	Type and quality of open spaces network (e.g. continuity) Diversity of habitats Extent and coverage of open/natural areas
	Climate change	Adaptation and resilience	Size and robustness of open spaces
Urban system	Urban sprawl	Compactness and containment	Management of urban expansion Quality and extent of open space infrastructure network
	Transport accessibility	Circulation flow Carbon efficient/environmentally sound	Connectivity Pedestrian and cyclist friendly Efficiency of Public transport network
	Land use	Efficiency Adaptation and resilience	Robustness of forms and functions Diversity of uses Mixed use accessibility

Table 4. Types of urban development; their characteristics and potential performance

Structure and form of urban settlements	Brief definition	Characteristics of open spaces in the urban settlement	Potential qualities and limitations	Typical urban form patterns
Compact Concentric (grid city, spider web)	High density, continuous, concentrated, centrality	- scattered - stepping stones, e.g., urban squares, small parks - larger areas of open spaces in the urban fringe, e.g., woodland regional park	- compact - large spaces in periphery: lung of the city - lack of continuity for air flow and biodiversity	Based on Paris, France
Linear Strip Corridor (Allain, 2004, Lynch, 1954)	High to medium density, continuous Long and narrow strip imposed by natural geographic conditions, e.g., mountain range or flood plain. Following transport infrastructure	- scattered in the urban fabric - continuous along the dominant infrastructure, e.g., blue/green corridor	- compact - protection of flood plain - continuity; green/blue corridor - diversity of open spaces, size and locations	Based on Stalingrad/Volgograd, Russia
Star shaped Compact extended with linear corridors of development	High to medium density, continuous urban development interspaced with open spaces	- scattered in city centre - continuous wedged of open spaces, e.g., agricultural land/green and blue corridors	- less compact - linear development favourable to transport corridor - continuity Green and blue dorridor - critical mass of open space favourable to wind flow/biodiversity and water management	Based on Copenhagen, Denmark
Polynucleated Polycentric with structure Network of Nodes	Medium to low density Cluster of nuclear settlements covering a wide territory linked by transport network and green infrastructure	- Each nucleus has their own small scattered open spaces - Dominance of large open land around which the various urban settlements are clustered. E.g., agricultural land/flood plain	- open spaces concentrated not spread out - central critical mass of open land favourable to biodiversity and water management and/or agriculture-	Based on Green Heart, the Netherlands
Scattered Polycentric discontinued	Low density, non-continuous, dispersed, interspersed with vacant land. The dispersion of urban settlement is linked to geographical conditions, e.g., topography/flood plain	-scattered overall on a large area - the non-built areas has diverse land use, e.g., agricultural/flood plain/mountains. - more formal open spaces are located on the periphery of the various built areas.	- use of large quantity of open land - taylored to each settlements but mainly small spaces - lots of gaps for water/wind/agriculture - no continuity	Based on Salzburg, Austria

Note: These types of developments illustrate generic macroforms. All urban settlements are unique and can follow principles derived from different types. Terminology adapted from Lynch, 1954, Allain, 2004

Table 5. Types of street patterns on le corbusier’s two types (Le Corbusier, 1929)

	Types	Variations	Qualities	Limitations	Layout Characteristics for all types
Pack Donkey’s Way	Ancient routes Vernacular/not drawn Based on Bari, Italy	Irregular Organic Based on Bologna, Italy	Responsive to natural characteristics (e.g. topography) and Desire lines Flexible Multi directional Diversity of experience Responsive to pedestrian movement	Complex Labyrinthic Poor legibility Limit air flow Difficult to retrofit	Juxtaposed pattern Extension Geometric planned pattern in continuation to organic vernacular Inserted pattern Minor modifications subdivision Substituted pattern Replacement e.g. old infrastructures: defence wall/canals Superimposed Major modification destruction e.g. large scale circulation infrastructure: Boulevard/ring road
		Irregular Concentric Based on Bologna, Italy
Man’s Way	Post industrial revolution planned/drawn Based on Bari, Italy	Regular Orthogonal Grid Based on Madrid, Spain	Simple Functional Legible Facilitate flows (circulation/wind)	Rigid Privilege fast traffic (motorised) Lack of diversity of experience
		Regular Concentric Based on Paris, France

Table 6. A range of types of street sections

Types of streets: Horizontal layouts/Orientations
Straight regular	Straight irregular	Curved regular			Curved irregular	Hybrid
Mono directional Main/landmark axis High visibility legibility Orientation key to solar access and ventilation	Diverse experience Orientation/microclimates legible circulation good visibility	Legible Less risk of wind tunnel effect Diverse solar access			Diverse experience and orientations/microclimates	Mutiple orientation No dominant wind direction Diverse orientation Less legible Less visibility
Street sections	Variations
Width: 3–10 m Lanes Old/vernacular streets Secondary streets
Width: 10–30 m Planned streets Main streets Commercial streets
Width: >30 m Boulevard Monumental streets Main axis of circulation
Generic considerations:
The larger the street the better the ventilation The larger the street the higher the sun exposure More shade in narrow street Wind tunnel effect in narrow street	Ratio height to width Tall buildings increase wind tunnel effect and limit solar access The larger the aspect ratio the quicker the night cooling			Larger pavements promote: diversity of uses increase pedestrian comfort water management tree planting

Table 7.. Street sections with pavement detail and elements for different types of streets and different widths (measurements based on Bentley, 1984; Jacobs, 1993; Marshall, 2009; Llewelyn- davies, 2007; Cameron et al., 2012)

	Commercial streets		Residential streets
Width between buildings and carriage way	Street components	Illustration	Street components	Illustration
Width < 2 m	Posts Lamp and other		Lamp posts Minimum threshold between public and private, e.g. steps
2 m < width < 7 m	Extension of indoor activities Minimum 1 m-clearance for posts, trees, bicycle racks, etc.		Lamp posts Street trees Hedge/wall/fence Small front garden
width > 7 m	Extension of indoor activities Posts Terrace Larger street trees (woodland type trees) Integrated water management, etc.		Lamp posts Larger street trees Hedge/wall/fence Large front garden with diversity of vegetation (shrubs/trees)
Observations	The larger the pavement/area not dedicated to motorised traffic the greater the opportunities to respond to the sustianability agenda including: Comfortable movement/Pedestrian and cycle network Social interaction Mitigation measures including Tree planting to provide shade, evapo transpiration and wind break CO2 absorption. Water absorption Integrated water management to limit run-off including porous surfaces and water retention features		The longer the front garden (if not paved) the greater the opportunities to respond to the sustainability agenda including: ensuring privacy less noise and pollution diversity of uses including play increase biodiversity water absoption

Table 8. Types of public squares

Types of public squares	Illustrations of configuration	Qualities	Limitations
Rectangle Courtyard		Enclosure Strong edges Destination Sheltered from outside conditions (e.g. noise/circulation)	poor connectivity static isolated
Circular rounded		Continuity of façade Unity Sheltered from outside conditions (e.g. noise/circulation)	poor connectivity static isolated no hierarchy/specific direction
Funnel Trapeze		Enclosure Directional Connection on one side Framing of view	limited connectivity exposed to outside influences and conditions (e.g. noise, circulation, flooding)
Enlargement Directional		Good connectivity with the linear open space Good visibility Good footfall Dynamic	dependent on the quality of the linear open space exposed to outside influences
Forecourt Front space		Monumental space within spatial sphere of landmark building Destination Good amenity value for indoor outdoor activities ceremonial	dependent and subservient to the building
Hub Intersection		Good connectivity/dynamic Distributor of movement flows Focus point (if complemented with a landmark feature) legibility	can be limited to a passing by/en route space exposure to wind if oriented towards dominant wind direction
Link Joint		Part of a network Interconnectivity Wider shed of influence (visual and physical)	can lack personality/identity can be limited to a passing by/en route space exposed to outside influences
Node Central		Multiple access multidirectional Meeting point Wide zone of influence Visual impact Dynamic/busy	can be dominated by movement flow limited space to rest

Table 9. Types of squares: spatial qualities and experiences in relation to permeability

Types of squares Spatial qualities and experiences in relation to permeability
Generic type: Enclosed open space/courtyard
Access and connectivity variations
Destination		Circulation
Qualities	Limitations	Qualities	Limitations
Outdoor room/strong ownership/local impact Opportunities for static activities such as Markets/café terraces Potential for tree planting and water features	Limited connectivity Limited visibility Limited wind flow	More public Well connected Good visibility Good wind flow Node for circulation Opportunity for central focus point (sculpture/fountain)	Limited ownership Less opportunity for static activities Limited space for tree planting
Examples of edges and layouts variations

Table 10. Characteristics of various types of open spaces networks and their potential performance

Types of open space infrastructure	Illustration of configuration	Impact on human comfort, natural and urban systems
		Qualities	Limitations
Green and blue corridor		- continuity - legibility - following existing natural infrastructure, e.g. river - potential transport corridor	- not spread out, more difficult to access except for areas along the corridor - impact limited along the corridor
Wedges		- multidirectional - can follow natural infrastructure/topography - Interrelated to built forms - easy to access - positive impact for wind flows. - good structure for urban expansion	- could lack diversity (dependent on use of wedges) - does not encourage compact city forms
Belt		- limit urban sprawl - protect open land - multiple uses, activities and character	- limited urban expansion - surround urban development not penetrating into it/limited impact not linked to dominant flow or natural infrastructure (wind/water) - limited access
Star		- flexible hybrid solution - easy access - can be linked to natural infrastructure and flows	- less legible - difficult to retrofit
Lungs/Urban fringe large open spaces		- if well located can have impact on compact settlements - multiple uses, activities and character	- location is critical - difficult to retrofit - limit urban expansion
Small neighbourhood parks		- diversity and multiplicity - easy access - clear identity and ownership.	- size limit function and potential impact - no continuity - no link with natural flows and/or infrastructure
Central park		- easy access due to centrality - critical mass/multiplicity of uses and activities - central feature for new development	- limited impact mainly in the area surrounding the park - no link with natural flows and/or infrastructure - impossible to retrofit
Linear park (disused infrastructure)		- continuity - potential transport corridor - positive impact on urban regeneration	- recycling of existing space - limited impact - not necessarily legible/can be a hidden structure - limited access

Table 11. Illustration of potential application for urban investigation; three squares in sheffield

Place	Forms (same scale/same orientation)	Characteristics				Observations
		Type	Access and connectivity	Hard surface	Tree cover
Cathedral square		Forecourt For the Cathedral Enlargement	High Destination Public transport (tram)	99%	1%	Functional High level of publicness Good gathering space Poor environmental considerations Varied microclimate
Paradise square		Courtyard	Low Enclosed Out of main routes	100%	0%	Strong ownership Local impact No environmental considerations (car park) Sheltered/limited wind flow
Fargate		Funnel Node/Hub City/commercial centre	High Crossing point Multiple directions	99%	Less than 1%	Limited level of enclosure High level of publicness Limited ownership Main function is circulation Windy

Geisler, W. (1918). Danzig: Ein siedlungsgeographischer Versuch. Druck von A.W. Kafemann.

 Google Scholar

Conzen, M. R. G. (1960). Alnwick, Northumberland: A study in town-plan analysis. Institute of British Geographers.

 Google Scholar

Muratori, S., Bollati, R., Bollati, S., & Marinucci, G. (1963). Studi per una operante storia urbana di Roma. Consiglio Nazionale delle Ricerche.

 Google Scholar

Castex, J., Celeste P., & Panerai, P. (1980). Lecture d'une Ville: Versailles. Le Moniteur.

 Google Scholar

Allain, R. (2004). Morphologie Urbaine. Armand Colin.

 Google Scholar

Kropf, K. (2017). The handbook of urban morphology (1st ed.). Wiley.

 Google Scholar

Moudon, A. V. (1989). The role of typomorphological studies in Environmental Design Research, University of Washington. [accessed, 20(12), 19]. https://www.scribd.com/document/213737939/Vernez-Moudon-n-d-The-Role-of-Typomorphological-Studies

 Google Scholar

Moudon, A. V. (1994). Getting to Know the Built Landscape: Typomorphology. In K. A. Franck & L. H. Schneekloth (Eds.), Ordering Space: Types in Architecture and Design (pp. 289–311). Van Nostrand Reinhold.

 Google Scholar

Hiremath, R. B., Balachandra, P., Kumar, B., Bansode, S. S., & Murali, J. (2013). Indicator-based urban sustainability—A review. Energy for Sustainable Development, 17(6), 555–563.

 Web of Science ®Google Scholar

Bentley, I., McGlynn, S., & Smith, G. (1985). Responsive environments : A manual for designers. Architectural Press.

 Google Scholar

Barton, H., Davis, G., & Guise, R. (1995). Sustainable Settlements: A Guide for Planners, Designers and Developers. UWE Bristol and LGMB.

 Google Scholar

Whitford, V., Ennos, A. R., & Handley, J. F. (2001). “City form and natural process”—indicators for the ecological performance of urban areas and their application to Merseyside, UK. Landscape and Urban Planning, 57(2), 91–103.

 Web of Science ®Google Scholar

Haughton, G., & Hunter, C. (1994). Sustainable Cities. Routledge.

 Google Scholar

Marshall, S. (2009). Cities, Design and Evolution. Routledge.

 Google Scholar

Carmona, M., & Giordano, V. (2012). Design Coding Diffusion of Practice in England. UCL and Urban Design Group.

 Google Scholar

Wolfrum, S. (Ed.). (2015). Squares: Urban spaces in Europe. Birkhauser.

 Google Scholar

Lenzholzer, S. (2015). Weather in the City. Nai010.

 Google Scholar

Lynch, K. (1954). The Form of Cities. Scientific American, 190(4), 54–63. doi:10.1038/scientificamerican0454-54

 Google Scholar

Corbusier, L. (1929). The Pack-donkey’s way and the man’s way, The City of Tomorrow and its Planning. In M. Larice & E. Macdonald (Eds.), The Urban Design Reader (pp. 90–93). Routledge.

 Google Scholar

Jacobs, A. B. (1993). Great Streets. MIT Press.

 Google Scholar

Llewelyn-Davies, R. (2007). Urban Design Compendium. English Partnerships.

 Google Scholar

Cameron, R., Blanuša, T., Taylor, J., Salisbury, A., Halstead, A., Henricot, B., & Thompson, K. (2012). The domestic garden – Its contribution to urban green infrastructure. Urban Forestry & Urban Greening, 11(2), 129–137. doi:10.1016/j.ufug.2012.01.002

 Web of Science ®Google Scholar