Anis, Sean, Sen, Osman MSc Dissertaiton 2013-14 by ombretta romice

Declaration of Originality â&#x20AC;&#x153;I hereby declare that this dissertation submission is my own work and has been composed by myself. It contains no unacknowledged text and has not been submitted in any previous context. All quotations have been distinguished by quotation marks and all sources of information, text, illustration, tables, images etc. have been specifically acknowledged. I accept that if having signed this Declaration my work should be found at Examination to show evidence of academic dishonesty the work will fail and I will be liable to face the University Senate Discipline Committee.â&#x20AC;? NAME: Siti Anis Abdullah, Sen Chen, Osman Hassan Khalifa Osman, Sean Stephen SIGNED: DATE:

Continuing ‘Alterations in Scale’: An Exploration of Walkability in Physical Urban Frameworks from Antiquity to the Era of Professional Urban Design Theory

Siti Anis Abdullah, Student No. 201390625 Sen Chen, Student No. 201363532 Osman Hassan Khalifa Osman Student No. 201381949 Sean Stephen Student No. 201387988

Acknowledgements

First and foremost, we would like to express our deep gratitude to both Professor Sergio Porta and Dr. Ombretta Romice who have overseen this research. It is their supervision and indeed, support, that has helped push us towards this â&#x20AC;&#x201C; the culmination of our year-long master â&#x20AC;&#x2122;s programme in Urban Design. Whilst at times challenging, our dissertation has ultimately been a rewarding experience; due in no small part to their guidance and support. The team would also like to thank family, friends, colleagues within the department, and of course, each other for their constant support throughout this summer. Thank you all.

ABSTRACT This dissertation aims to develop a collection of evidence demonstrating the influence that the now-confirmed 400 meter principle holds over levels of walkability. Using a large-scale morphological comparison study, we have examined the degree of walkability across cities of different social, economic, geographical and historic conditions using a carefully selected set of indicators that have been derived from an extensive literature review undertaken by the study team. This research builds upon the work of Porta et al (2014) and their efforts in establishing a proven theoretical basis surrounding the hypothesised ‘400-metre’ rule – a consistent morphological pattern observed amongst main street networks in traditional urban areas. Their research, ‘Alterations in Scale’, measured the length of main street segments from a set of 100 case studies, grouped according to the prevailing design paradigm – Historical, Garden City, Radiant City, New Urbanism, as well as informal settlements. Findings revealed that cities, right through from antiquity to the periods in time just prior to professional urban design theory, were seen with very little exception to exemplify this 400-meter ‘rule’ (Ibid). Beyond this point in history (up to and including the post-modern theories of new urbanism) the distance between main streets in these networks roughly doubled. Our research, Continuing Alterations in Scale, answers Porta et al’s call for further evidence-based approaches to the study and design of the built environment; building upon on the theoretical foundation established in the original Alterations in Scale. The documented shift in scale suggests clear implications for the levels of walkability in each of these places, and in an ideological continuation of this work, we have attempted to further investigate the associated physical characteristics in both the aforementioned 400m and non-400m scaled examples. The evidence will attempt to reveal that the clear point in history at which the 400 meter principle was abandoned coincided with a relative decrease in levels of walkability. Not only will this highlight a perceived weakness in contemporary urban design and practice, but it will point to potential implications within the current place-making and sustainable urbanism agendas.

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This piece of research constitutes the MSc dissertation component of the (taught) postgraduate course in Urban Design at the University of Strathclyde. The authors each share a keen interest in some of the major learning themes that have been delivered by the Urban Design Studies Unit (UDSU) during their studies, and now hold a common desire to contribute to the unit’s current research stream; specifically concerning contemporary debates in urbanism surrounding the concept of urban morphology and ‘built form’.

Introduction

The physical characteristics of our towns and cities are perhaps as varied and diverse as the people that live, work, and play in them. How they look, how they sound, how they smell, and how they make us feel all play a major role in defining our experience of that place. Whether these characteristics are visceral and obvious, or whether they are subtle and engrained deep within the urban fabric – they all play a role in how we are able to interact, move, and express ourselves – subconsciously or otherwise. Specifically, it is the interplay between the physical environment, built form and our propensity to move safely, comfortably, and easily as a pedestrian that concerns this study. This of course, refers to walkability. The concept of a ‘walkable neighbourhood’ is one which has featured prominently throughout our learning this year. Our studies have seen us both attempt to further our understanding of the concept, as well as actually putting our knowledge into practice and designing them as well. This has understandably fostered a significant appreciation of how such environments can contribute to sustainable, liveable cities. This piece of research continues this appreciation by building upon the work of Porta et al (2014), who conducted a largescale morphological comparison of urban frameworks from throughout the history of human settlement; from as far back in time as antiquity, right up to the latter decades of the 20th century which saw town-building according to strict new urbanist principles. ‘Alterations in Scale’ produced a series of findings that indicated a clear shift in urban scale over the course of human history; moving beyond what was considered to be the historic, human-scaled framework with the advent of professional urban design theories. The alteration in scale of the main street network may, by extension, imply a similar shift in scale for many of the other crucial ‘sub-structures’ of urban form such as blocks or plots (Ibid) – sub-structures which have shown to hold significant influence over walkability. ‘Continuing Alterations in Scale’ aims to develop a collection of evidence demonstrating the influence that the now-confirmed 400 meter principle holds over levels of walkability. The project has examined the degree of walkability across cities of different social, economic, geographical and historic conditions using a carefully selected series of indicators; each justified in their usage as a result of the extensive literature review undertaken by the study team. This dissertation is therefore structured as follows. The first chapter consists of a wide-ranging review of existing literature on the subject of walkability, in which we acknowledge its broad relevance and multi-disciplinary scope before defining it within a context appropriate to our own study (where physical features and urban form are central). This is followed by a thorough examination of the main influencing factors. Chapter 2 consists of succinct review detailing how the many aspects of walkability have been measured within literature, and will go some way in establishing a set of ideas upon which to create our own indicators. Chapter 3 provides subsequent detailed methodology for study before the analysis and synthesis of findings in Chapter 4.

Chapter 1 | Walkability in Theory

An Introduction to Walkability The emergence of ‘sustainable development’ as a popular concept has arguably galvanised discussion regarding the form of cities across the broad spectrum of urban studies (Jabareen, 2006). With contemporary discourse amongst urbanist academia and mainstream policy beginning to support the ideals of new-urbanism and smart growth, greater consideration is being given to the potential re-shaping of existing unsustainable urban form. Serious questions are now being asked of the extent to which form can both adapt and change – specifically in terms supporting more ‘pedestrian-friendly environments’ (Özbil, 2010). With approximately 70% of the earth’s population expected to live in urban areas by the year 2050 (United Nation State of the Cities Report, 2012), it is paramount that we attempt to further existing understandings between form and its effects upon the streetuser in order to enable built environments that provide and function in a manner far more constructive than they appear to be at present (Jabareen, 2006). In terms of research, there is a clear need to identify the characteristics that hold the most ‘explanatory power’ with regards to this relationship between form and street-user, and there is a growing body of literature attempting to objectively measure this – often utilising a wide variety of innovative approaches and methodologies (Leslie et al, 2007). However, the specific conditions that any research attempts to quantify are arguably all components of a broader, all-encompassing term that better describes the aforementioned ‘pedestrian-friendliness’ whilst maintaining an equal focus on the overall ‘liveability’ qualities of the urban environment. This term is ‘walkability’, and it is this concept that Continuing Alterations in Scale is concerned with. Some commentators have suggested that it is far too nuanced a concept to hold just a single definition (Lo, 2009); any interpretation is likely to be heavily influenced by the theoretical or practical context of those attempting to measure it. Talen & Konchesky (2013), too, note with interest the extent to which disciplines with what appear to be ‘divergent interests’ are connected to this overarching concept – it is one which is currently “motivating scholarship in a wide variety of fields, and generating research results with crosscutting applicability” (Talen & Konchesky, 2013 p.43). Walkability studies have been conducted within the fields of transport and engineering, economics, social science, health studies, and of course, planning and urban design. Where one study may examine pedestrians and their attempts at navigation through urban form, another may consider the physical and well-being of those living in purported ‘walkable neighbourhoods’; both will have differing interpretations of walkability and both will exhibit slight bias towards the theoretical basis of their respective studies. Despite these assertions of complexity, a recurring theme in any plausible definition is the extent to which urban form and the built environment are key factors (Leslie et al, 2007). Thus, walkability is largely agreed to be: “The extent to which the built environment is friendly to the presence of people living, shopping, visiting, enjoying or spending time in an area” (Abley, 2005 p.3) If we were to imagine an urban environment with high walkability, it would be one that: is clean and enjoys low-levels of carbon emissions; is centrally located and in close proximity to important amenities; is well connected; hosts a diverse range of uses; is pedestrian-friendly; and is safe. Most commonly associated with place-making and the new-urbanist agenda, the extent to which a given place is, or can be made, ‘walkable’ has significant implications for both sustainable urban planning and design, and indeed, the future of our urban environments (Jabareen, 2004). A truly walkable environment is one which prioritises ‘people outcomes’ above all else; it is one which by necessity challenges the ‘old thinking’ and assumptions pertaining to auto-dependency and the conditions created through ‘ready-made fragments of self-containing urbanism’ as seen in the likes of Howard’s Garden City, or Le Corbusier’s Radiant City (Mehaffy et al, 2010). First hypothesised by the great Jane Jacobs, these models, which often forego the need for walkability and connectivity in favour of vehicular movement and higher proportions of open space, have been shown to contribute to the eventual decline of their respective urban contexts (Jacobs, 1961) – one only has to look at the likes of Pruitt Igoe in the United States for such an example.

Indeed, Mehaffy et al (2010) use contemporary data to point to the potential consequences (in this case, social and economic) of unsustainable urban form, noting that the disconnected, outlying, auto-dependent suburbs of the United States saw disproportionately high numbers of foreclosures towards the end of the last decade. Elsewhere, a growing body of health research has proven a direct correlation between increased walkability and positive health outcomes for those living there; acknowledging both the holistic and physical benefits afforded through safe, pleasant environments that encourage greater personal movement. Crucial to this study is Talen & Konchesky’s affirmation that the ‘walkable neighbourhood’ (and by extension, walkability) is a “physical phenomenon— a bounded place in a given spatial location with selected material properties” (Talen & Konchesky, 2013 p.43). What is therefore required is a thorough examination of walkability – to “identify and to document objectively” the physical characteristics that have the potential to assert some form of influence (Leslie et al, 2007 p.112). This will be done through a careful consideration of some of the wider literature devoted to this particular subject and will comprise the information found in the remaining pages of this chapter. Following a further examination of how such concepts are quantified (see Chapter 2), this will then contribute significantly in informing our own study methodology. Factors Affecting Walkability Connectivity Streets constitute one of the principle components of any city – they facilitate movement; they are a means of navigation; they define the constituent neighbourhoods and blocks; and are, according to more recent theoretical standpoints, centres for urban vitality and human activity. The extent to which these exist in a well connected, well ordered manner is therefore likely to have significant implications for the levels of walkability in a given area. Saelens et al (2003), in their review of physical environmental conditions that are considered to influence and encourage greater ‘non-motorised’ forms of transport, have indeed identified street connectivity as one of two principle causal factors (the other being proximity to potential destinations). This is again hypothesised by Norman (2006), and Pentella (2009), who have both reinforced connectivity as a key determinant of walkability in their respective studies. At a physical level, connectivity represents the inter-connectedness or ‘permeability’ of a street network and affects the degree to which people can easily navigate towards their destinations. The ease with which this takes place – the ‘cognitive effort required’ (Frank, 2004) – in turn determines the extent to which we would consider a particular piece of urban form walkable. Direct travel (and therefore a higher degree of walkability) is clearly stronger where there are limited barriers to movement, shorter distances, and numerous intersections and routes (increasing the potential number of options for travel). The optimum configuration (i.e. one with highest levels of walkability) is that of the grid structure (Talen & Konchesky, 2013) where, in a practical sense (due to finer grain elements design elements) pedestrian movement can rival and in some cases surpass the efficiency of the motorised transportation network (Frank et al, 2003). This is perhaps best surmised by the following quote from the Planning Institute of Australia: “Good connectivity provides easy access to key destinations for pedestrians. Excellent connectivity actively seeks to discourage car use by making local trips easier and more pleasant by foot than by car.” (Health Places & Spaces Australia, 2009). Proximity Proximity is the second principle factor identified by Saelens et al (2003) which is purported to hold a great degree of influence over levels of walkability. Whilst the term in itself may seem relatively abstract, it concerns the relationship between both the destination and origin of a journey, and is governed by what some commentators (Leslie et al, 2005; Kubat & Ozer, 2013) consider to be two inter-dependent sub-variables that together, constitute this composite influence.

The first of these is density, and relates to the “compactness of land use” (Leslie et al, 2007 p.113) and the extent to which the resultant fine grain form can improve transit for pedestrians by providing “relatively direct routes, thus reducing the distance between origins and destinations.” (Kubat & Ozer 2013 p.4). The second is land-use mix, or the “degree of heterogeneity with which functionally different uses are co-located in space” (Leslie et al, 2007 p.113). Higher density neighbourhoods have been shown to encourage far greater mixed-use development (Cervero & Kockelman, 1997) and this combination of both diversity and supporting density can effectively ‘shape’ pedestrian activity by bringing a greater number of activities closer together (Pentella, 2009). Crucially, research supporting this notion has revealed that people are far more open to the prospect of walking over short distances, especially if many trips can be ‘chained’ together – i.e. visiting different amenities for different purposes within close proximity to one another (Marshall & Grady 2005). The clustering of important amenities may also be construed as a ‘grouping’ of points of interest that contribute significantly to the facilitation of choice amongst the street-user. This idea forms the basis of certain observations put forward by the Jan Gehl in which he asserts that higher quality pedestrian environments are those which display a higher ratio of ‘optional’ as opposed to ‘necessary’ trips (Gehl & Gemzøe 1996). Environments exhibiting these characteristics are far more likely to see people staying put as opposed to simply passing through (Lo, 2009), allowing for the hypothesised vitality, sense of security, and ultimately walkability afforded through the presence of others (Jacobs, 1961). In order for a neighbourhood to therefore exhibit walkable characteristics, Frank (2004) warns that walking (as a form of transport) must be able to viably compete with other modes of travel in terms of its ‘relative utility’, and that the individual should not be disadvantaged in any way with respect to the distance travelled. Indeed, earlier research undertaken in the United States examining pedestrian travel patterns reported that distances half a mile or less between major amenities are desirable, with the relative utility of walking ‘dropping off’ as the distance between destinations increases beyond this (O’Sullivan & Morrall, 1996). Continuity & Sidewalk Condition Crucial for easy and safe navigation for those travelling by foot; the extent to which the supporting pedestrian infrastructure (i.e. sidewalks and crossings) exists in a complete state is another potential factor influencing both actual and perceived levels of walkability. Like the two factors discussed above, the state of the pedestrian network (both in terms of physical maintenance and aesthetic design) exerts some degree of influence over the extent to which an environment can provide an uninterrupted trip that offers the user freedom and choice of movement as well as a relative feeling of security. Furthermore, the prospect of a fully continuous sidewalk network chimes strongly with the urban design ideals of walkability in the sense that it is accessible to all users of the neighbourhood – particularly to those that require the use of wheelchairs or mobility scooters or for parents with prams/strollers. In terms of ‘gaps’ in continuity, these can come from missing or broken segments of the sidewalk, or simply stretches that are insufficient in terms of design (for example, width; thereby creating potential restrictions for the amount of people that could comfortably walk side-by-side). Continuity, however, may also refer to the extent to which a continuous built front exists as part of this network. Park (2008) is one such source that recognises the theoretical basis, and indeed value, of a cohesive and constant network of visually engaging facades but equally acknowledges that there have been few studies attempting to quantify this in more detail. That said, it should be note that such an indicator is used as one of the determinants of walkability for the LEED ND initiative; a sustainability certification programme in the United States that recognises best practice in the fields neighbourhood design. Visual Interest & Aesthetics As an aside from the more mainstream urbanism disciplines such as planning or transport studies, urban design discourse has placed an increasing focus on walkability metrics that consider the built environment at a much finer grain. This growing body 5

of research focuses on the quality of service, the aesthetics and indeed, the sense of place afforded through the physical conditions, as opposed to simply gauging the “transportation efficiency or connectivity of pedestrian facilities.” (Lo, 2009 p.157) Kevin Lynch is often regarded as one of the most preeminent authors who dealt with this subject, postulating on the ‘performance dimensions’ of both cities and pedestrian spaces (Lynch, 1984). The works of lynch, of course, fall within a body of urbanist literature written by some of the most prominent figures in our discipline (see Cullen, Jacobs); works that marked a significant shift forward in existing understandings of towns and cities, and that now represent the principle tenets of contemporary urban design. What was so remarkable about these were the extent to which they revealed the individual, personal and emotional response to the city. Cullen (1971) in particular, made the case for a deeper understanding of how certain aesthetic values and physical characteristics can affect our experience of place – particularly as we walk through a neighbourhood. These writings constructed the city as series of distinct, ‘serially traversable’ spaces (Whistler & Reed, 1994) – the inherent qualities afforded as the environment changes can elicit a varied and diverse set of reactions. This is what Cullen ultimately referred to as the “drama” of the city (Cullen, 1971 p.10) and it is these changes that have the potential for the urban realm to be both interesting and enriching for the user. Some commentators such as Lo (2009), however, warn of the strong qualitative nature of such descriptors, and that there have perhaps justifiably been very few attempts at quantifying design characteristics in a more objective manner (i.e. quantitatively). One author who did attempt to do so was Jaskiewicz (2000), who focused primarily on the aesthetic appeal of the pedestrian environment (complexity of spaces and paths; street definition or enclosure; building articulation and variation; the presence of overhangs and variation in roof lines; buffers separating pedestrians and traffic, presence of shade trees and lighting). Whilst Jaskiewicz’s results provided a positive correlation between a greater propensity for walking and more ‘positive’ design characteristcs, Lo (2009 p.158) again points to potential weaknesses in this methodology – “part of the problem of developing aesthetic metrics for walkability is that design criteria are subjective by definition” and as such, is vulnerable to the aesthetic bias of the theoretical background and even the personal tastes of the researcher. Security & Sense of Comfort Debate surrounding the extent to which the relative sense, or indeed, perceived sense of safety can influence the walkability of a neighbourhood largely stems from the writings of Jane Jacobs. Her 1961 treatise, the “Life and Death of Great American Cities”, called for an increased focus on what she saw as sadly undervalued components of the physical urban environment; namely the sense of security and pedestrian comfort which Jacobs insisted was absolutely vital to the vibrant, liveable city (Jacobs, 1961). This gave rise to the oft-quoted ‘eyes on the street’, where Jacobs put forward the notion that security is both afforded and maintained through the presence of people – specifically the ‘proprietors of the street’ – whether this be pedestrians passing through, customers using amenities, or the owners of the property and amenities themselves. However, it is not simply the presence of other people that can elicit such an emotional response – Park (2008) showed a direct correlation between pedestrians’ sense of security and multiple design elements; one of which was the height of buildings and the relative scale of enclosure. In terms of documented relationships between street enclosure and walkability, David Spooner’s examination of Italian Streets is one of the more recent studies which has produced significant findings. His results indicated the extent to which certain building ratios inform the emotional response of the pedestrian at street level – with the optimum horizontal to vertical ratio revealed to be roughly between 1:1 and 3:1 (Spooner, 2007). This is not a new concept, having first been hypothesised as part of the early writings of the likes of Cullen (1971). Others have since added to the existing discourse, with studies from the Greenbie, (1981), Hedman (1984), and Tibbalds (1992), all acknowledging that beyond this ‘ideal’ ratio range (towards either extreme) will ultimately lead to a loss of enclosing properties and subsequent sensations of space. In some cases, the emotional response from the street user was described as both claustrophobic and uncomfortable.

Beyond the sense of enclosure afforded through particular street ratios, it has also been suggested that building height alone may inspire a sense of comfort and security. Regardless of whether occupants were actually present within a building, Park (2008) demonstrated that to pedestrians, more floors were associated with more windows thus providing a greater number of ‘eyes on the street’. Other elements which are considered to hold influence over levels of walkability are: the degree of ‘transparency’ in ground floor frontages (in other words, the extent of ground floor activation – a principle tenet of new urbanism considered highly conducive to liveable, walkable environments), and; the proportion of built frontage (where the block itself ‘engages’ with the street user, providing a perceived ‘safe’ environment as well as visual interest). This last descriptor is particularly important, given the works of other urbanists (in particular; Gehl, 1987) who have investigated the role of both ‘quasi-public’ and ‘quasi-private’ space and its role in contributing to street livability. Green Networks Well-designed and well-planned green networks have the potential to become invaluable components of liveable and indeed, walkable cities, and can represent a major asset in the quest for social and infrastructure cohesion amongst communities (Tate, 2001). The psycho-spatial relationships between the physical environment and both. This ever-growing body of research has revealed that the influence of green networks over levels of walkability is most often realised through extent to which the associated neighbourhood characteristics produce greater positive health outcomes for those living there. The explanatory correlation appears to be that once a pleasant, cohesive green infrastructure is in place (this may include planted tree lines, well-maintained paths or gardens), this strong ‘natural presence’ then positively influences motivation for physical activity within that environment (Suminski et al, 2005). Ellaway et al (2005) for example, submitted that in a study of European adults, residents living in areas with what were ranked as containing the ‘highest’ levels of greenery were almost three times as likely to be physically active (in addition to experiencing higher levels of positive health outcomes). These findings have been echoed by studies in both the United States (Li et al, 2005) and in Japan (Takano et al, 2002), where the provision of green infrastructure was considered an important determinant of walking. Additionally, it has been suggested that a lack of greenery along streets will produce similarly impactful results. Tilt et al (2007) revealed that residents in neighbourhoods ranked as ‘less green’ (i.e. lacking in coherent green infrastructure or attractive environmental features) exhibited a strong inclination to perceive distances as longer than they were in reality, in turn reducing the likelihood of walking. Impacts and Implications of Walkability Having examined the major influencing factors relating to walkability, this research has by necessity, given consideration to some of the resultant impacts of the more walkable examples of urban form – authors from across the broad spectrum of urban studies have used these observable measures to further their understanding of both the concept and how such relationships hold influence. The impacts associated with high walkability tend to fall within two disctinct schools; health and wellbeing, and economics. It would appear that one of the best-established and indeed, most studied aspects within epidemiology is the relationship between walkability and BMI (body mass index). Studies from around the world have proven this direct correlation within varying contexts; from inner city studies in the United States (Konikov-Titievsky, 2010) to longitudinal studies in suburban Australia (University of Melbourne, 2013). In each case, the observed characteristics of the area conspire to create an environment which is inherently more walkable. For example, in an investigation of walkability and the associated levels of both BMI and cardio-respiratory fitness in Texas, Hoehner et al (2011 p.2) concluded that neighbourhoods exhibiting characteristics “hypothesized to support more physical activity” were clearly associated with higher levels of positive health outcomes. In the main, the methodologies employed in these cases do incorporate the physical elements of built environment. However, it should be noted there have been calls from some corners (Lopez et al, 2006) for a greater incorporation of built environment factors within health studies in order to reinforce this relationship. 7

Further benefits have been reported through anecdotal evidence regarding the more holistic benefits afforded through walkable neighbourhoods; namely in an increased sense of community cohesion and social interaction. With regards to the economic benefits, these have principally been quantified in respect of property value. Using one of the most widely available tools for measuring walkability; the WalkScore tool, Cortright (2009) was able to demonstrate the hypothesised ‘walkscore effect’ upon the value of properties in neighbourhoods that scored within a certain bracket. Examining the data for over 90,000 home sales in the United States, researchers were able to prove a positive correlation between walkability (defined in this case according to WalkScore; namely involving travel distances and proximity to major amenities) and house prices. A one point increase in ‘neighbourhood score’ represented an approximate increase in between $700 and $3,000 in home value. These findings suggested that both housing markets and consumers attached significant positive value to walkable neighbourhoods.

Chapter 2 | Walkability in Practice

The previous chapter noted many examples of the recent increase in academic focus over the subject of walkability; in many cases transcending urban studies and encroaching on a wider range of disciplines including economics and health. This has led to the creation of both a diverse and significant collection of measurable characteristics which researchers have used for the specific purposes of empirical evaluation. What this shows, however, is that there is no ‘one’ metric appropriate for use across the spectrum of walkability studies. The Project for Public Spaces recently commented on the benefits derived from this growing body of knowledge, and that whilst it has indeed revealed “more commonalities than differences” they note that “people and places are unique, and walkability tools will need to adapt” (Project for Public Spaces, 2011) – clearly the tools used are also highly dependent on both the context of each respective study and the discipline within which the research falls. As such, this brief review of ‘walkability in practice’ will examine the ways in which methodologies have been used, as well as the ways in which they have since evolved in line with the establishment of walkable neighbourhoods as an explicit policy objective (Talens & Koschinsky, 2013). Furthermore, the review will serve to contextualise our own study; justifying our own methodology within the scope of the research aims and objectives. Talens & Koschinsky (2013) have noted how many of the measures now used in walkability studies have roots in simple, almost playful concepts – the basis of which rely on everyday assumptions and anecdotal evidence. These include: the ‘popsicle test’ – the idea that a walkable neighbourhood is one in which a child can (safely) walk to a shop, buy a popsicle, and return home before it melts; Larrabee’s ’20 minute neighbourhood’, where the individual’s ‘every-day needs’ can be met within a 20 minute walk (Larrabee, 2008), and; the ‘halloween test’, where neighbourhoods are rendered walkable depending on how good they are for ‘trick-or-treating (Benfield, 2012). Whilst hardly the most scientific of measurements, each of these ‘tests’ factors in key assumptions regarding a pedestrian’s propensity to walk – some of which actually form the basis of the most widely used and widely accessible forms of walkability measurement tools (for example, WalkScore). The most prominent and perhaps the easiest to measure relate to distance and dimensions; in other words, relating to the influencing factor of proximity as covered in the previous chapter. Methodologies that focus on this particular aspect of walkability do so on the “commonly accepted rule-of-thumb” that neighbourhoods have optimum distances at which important amenities should be placed (Talens & Koschinsky, 2013 p.45); between an approximate quarter or half a mile from the destination of origin (usually the home). This has been proven in multiple cases by the likes of Lee & Moudon (2006), Cerrin et al (2006), and Iacono et al (2010) in pedestrian travel research that has examined average walking pace – if a pedestrian walks at approximately three miles per hour (the hypothesised average pace), then a five minute walk would result in a quarter of a mile travelled, and 20 minute walk would see a full mile travelled and so on. Thus, ‘upper bounds’ can be established; revealing the extent to which pedestrians would be willing to walk to amenities (WalkScore, 2011). As a general point, it should be noted that the concept of a walkability ‘index’ or a series of composite measures, is one that is common across methodologies in all disciplines which hold some stake in the debate over walkability. This is clearly in line with our earlier assertions that no ‘one’ metric is appropriate for measurement – in part owing to the sheer number of ways in which walkability can be influenced. Much has been made of the robustness and transferability of findings from walkability indices and composite methodologies such as WalkScore; follow up studies from Carr et al (2010) and Duncan et al (2011) have indeed validated its accuracy in gauging levels of walkability (Talens & Koschinsky, 2013 p.45). But beyond simple distance-based measurements are calls for a further incorporation of physical neighbourhood design and aesthetic metrics within walkability methodologies.

Substantiating some of new urbanism’s claims regarding the impact of physical and morphological elements on the livability and vitality of neighbourhoods, studies within the last decade have shown direct correlation to greater place attachment and sense of community, ‘active aging’ and enhanced walkability (Leyden, 2003; Michael et al 2006; Wood et al, 2010). As such, many argue that these crucial micro-scale elements – core urban design elements directly influenced by form – are now “integral to the assessment of the walkable neighbourhood” (Talens & Koschinsky, 2013 p.46). Kashef (2011) hints at the attribute of street connectivity as being one of the ‘easier’ to measure given both its prominence in existing research and the consistent methodology that has been employed throughout. This particular measure of walkability emerged as a specific built-form indicator in the relatively early work of Ewing (1996) who discussed the accessibility and ease of movement afforded through the design of smaller block sizes. In the vast majority of connectivity methodologies, the measure is quantified using ‘street centreline data’ (basic network data usually derived from GIS) and is concerned with the number of “unique street connections” that occur within a given area (Leslie et al, 2005 p.6). This calculates the ratio (or indeed, density) of intersections within a specific area; the reasoning being that higher densities provide people with greater choice in terms of potential routes, shorter journey times, as well as the possibility of more direct routes. Intersections in the almost all of the cases reviewed are concerned with intersections of three linkages and above. Leslie et al (2007) suggest that there is further data to be derived from such methods; namely in gauging the extent to which a given environment may have a complete or continuous sidewalk system. An urban environment exhibiting higher connectivity is more likely to have sidewalks; and through “this systematic co-variance...their presence may to some extent be captured by proxy.” (Leslie et al, 2007, p.113) Thus we can deduce that measuring the level of street connectivity may also provide some indication of completeness of the associated sidewalk network. It has been more difficult to pinpoint specific examples of measurements focusing on some of the other influencing factors identified in Chapter 1, for example – methodologies that specifically address things the continuity of blocks or presence of built front. One such example, as referenced by Talens & Koschinsky (2013) is the LEED ND initiative; a form of ‘standardised measurement tool’, that while not specifically focused on walkability, captures “qualitative differences of places in ways that largely define the separation between walkable and unwalkable places” (Talens & Koschinsky, 2013 p.47). LEED ND (Leadership in Energy & Environmental Design for Neighbourhood Design) is a sustainability certification programme in the United States that recognises best practice in the fields of building, planning, and design. In order to achieve ‘LEED certification’, projects must satisfy certain prerequisites. For example, in the case of sustainable neighbourhoods, there are very specific conditions relating to block design – of relevance to this review are the prerequisites for block continuity (no more than 40% of a block’s façade should be left blank); sense of enclosure (at least 15% of existing and new street frontage should have a minimum building-height-to-street-width ratio of 1:3), and; built frontage (at least 80% of the total linear feet of street-facing building façades in the project is no more than 8 metres from the property line). As stated previously, although these measurements are not aimed at addressing walkability per se, LEED ND views the ‘walkable neighbourhood’ as a central component of sustainable urbanism. We therefore see this as having some relevance to our own study; the prerequisites here obviously holding some potential for modification into a more cohesive methodology. Of course there is still some debate within academic discourse as to the most appropriate methodologies for quantifying the ‘unmeasurable’ characteristics of the street; factors such as the vitality or liveliness, sense of security and safety, or cleanliness (Ewing & Handy 2009). The challenges arise in attempting to quantify elements that are ultimately subjective, and then in attempting to apply this to what are often large-scale comparative studies of urban environments. According to Talens & Koschinsky (2013), researchers have gone so far as to engage regular street users (through focus groups and surveys) to find survey tools that are more appropriate. In many cases, this results in audit tools that review the environment from an ‘end user perspective’ of a street user.

One of the most prominent, and arguably one of the most widely used, is a style similar to the PERS (Pedestrian Environment Review System). Developed in the early 2000s in London with the intended users being both professionals and communities, this audit tool promoted itself as a “systematic process to assess the pedestrian environment within a framework that promotes objectivity” Allen & Clarke (2007 p.5). As previously stated, the audit takes place from the perspective of a street-user where those undertaking the audit are asked to rate a series of parameters on a sliding scale from -3 to +3. To strengthen the findings from the qualitative data, this is then aggregated against a more quantitative dataset through the use of GIS. This method has clearly had some success, with both Allen & Clarke (2007) and Davies & Clarke (2009) noting its global reach, as well as the fact that it has been used to effectively assess over 200km of street network in London. Similar methodologies to calculate walkability have seen success in the United States – particularly the Neighborhood Environment Walkability Scale (Cerin et al, 2009) – which again uses primary data from street users aggregated against broader quantitative data in GIS. With advances in geo-spatial computing software, the incorporation of GIS within methodologies has become increasingly common; allowing for a far greater depth of analysis, as well as the ability to draw even more meaningful conclusions. Studies such as Leslie et al (2007) and Pentella (2009) have shown this to be the case, where broader census and socio-economic data has been incorporated (through GIS) and has provided additional, valuable perspectives in their respective studies of walkability. Despite suggestions of an inability to ‘measure the unmeasurable’, or too heavy a reliance upon the ‘crude’ distance and dimension metrics, it is clear that methodological tools are being constructed that are able to measure walkability and provide meaningful results. After a careful review of some of the most prominent literature to engage the subject, it is clear that the specific tools used are most likely to be dependent on the respective contexts (and of course, disciplines) of each study. Given the largely physical nature of Continuing Alterations in Scale’s focus – that of walkability within specific types of morphological form – it is encouraging to see that extent to which tools like WalkScore (dealing primarily with built metrics) have had success. Indeed, some commentators (namely Weinberger & Sweet, 2011) have revealed through follow-up studies that such tools are undoubtedly valid as proxy measures for walkability.

Chapter 3 | Continuing ‘Alterations in Scale’: Scope and Link to Previous Study

Context for the Study As the title of our masters’ dissertation suggests, our research builds upon the work of former students of the UDSU and their efforts in attempting to establish a proven theoretical basis surrounding the hypothesised universal ‘400 metre scale’ within physical urban frameworks (Porta et al, 2014). This in itself supports the work of Mehaffy et al (2010) in building a case for the ‘emergent neighbourhood model’ of urban framework planning – a proposed approach that favours (and enables) the organic growth of communities as opposed to a more rigid ‘social engineering’ approach (Ibid). In terms of support for Mehaffy et al’s case, ‘Alterations in Scale’ revealed the existence of an optimum balance between pedestrian and vehicular mobility – one that was consistent in cities around the world regardless of geographical location or culture. The principle finding was that this balance shifted beyond what would ideally be considered at a ‘human scale’ as urban development progressed through history into the realms of Professional Urban Design Theory – this referring to “the models and conceptual formations that structured the gradual codification of architectural and urban design as professional disciplines between the end of the nineteenth century and the early decades of the twentieth century” Baird et al (2010 p.11). The establishment of this principle suggests clear implications for the levels of walkability in each of these places, and in an ideological continuation of this work, we have attempted to further investigate the associated physical characteristics in both the aforementioned 400m and non-400m scaled examples. It is hoped that this research will go some way in answering the calls of Porta et al (2014) for a stronger “evidence-based approach to the study and design of the built environment” within their own work. This is particularly appropriate given the concerns of some contemporary urbanists regarding the lack of a truly unified, data-driven theoretical foundation (De Chant, 2012), and wider calls in attempting to establish a true ‘science of cities’ by the likes of Luis Betterncourt et al (2007) and more specifically, Michael Batty (2012). Within current academic discourse, we would argue that less prominence has been given to the relationship between walkability and built form at its most basic level (i.e. the balance and interplay between buildings and streets). Acknowledging this potential knowledge gap and recognising the legitimacy of the findings in Alterations in Scale has provided the stimulus to undertake this particular piece of research, and it is here where we seek to further explore walkability across specific urban forms through a careful examination of their physical characteristics. Understanding ‘Alterations in Scale’ Central to the completion of our own work was developing a thorough appreciation of the motivations, methodological approach, and subsequent findings of Alterations in Scale. This in turn, relied on our study team understanding the basic premises put forward by Mehaffy et al (2010). Many of these concepts are worth revising in order to develop a full appreciation as to how they influence the subject of our own study; walkability. The 400m rule is based on initial observations made by Mehaffy et al (2010) which hint at a possible shift in the scale of contemporary street networks – specifically at the start of the 20th Century. Prior to this point in time, urban form had largely been defined according to a patchwork of neighbourhoods or ‘sanctuary areas’ (Appleyard, 1981), bound by main streets that intersected at distances of no more than 400m. This obviously reflected the prevailing historical conditions; of the “limitations of pedestrian movements and the self-organising logic of social urban life” (Porta et al, 2014 p.2) – all prior to widespread use of the automobile or the application of 20th Century ‘urban design paradigms’ (Mehaffy et al, 2010). As Porta et al (2014) argue, the manner in which people have organised themselves into neighbourhoods across the breadth of human history has clearly been organic. This process produced an appropriate scale of human walkability without the need for professional urban theorists, before the likes of Clarence Perry “decided that it was in everyone’s best interest” (Baird et al, 2010 p.15). Howard’s Garden City (Howard, 1902) was ultimately the start of a reversal of centuries-worth of practically and appropriately scaled urban settlement – compacted of course by the subsequent theoretical development of the Neighbourhood Unit (Perry, 1929), and the Radiant City (Le Corbusier, 1933). The associated impacts were realised in the loss of any sort of consistent spatial pattern (in terms of form) and a sizeable expansion of the length of main street segments (Porta et al, 2014) – again, indicating a shift beyond the traditional human scale most commonly associated with historical cities. 12

Research that sufficiently tests these observations is clearly going to have to be of significant scope – the possible case studies available for consideration could effectively be one of many hundreds of cities around the world. In order to do just this, Baird et al (2010) compiled a diverse set of 100 examples of main street networks; spanning different geographical, social, economic, and most importantly, historical systems. Case studies were then grouped according to three distinct theoretical categories: case studies originating in a pre-professional theory of urban design era; case studies originating in the professional theory of urban design era, and; case studies originating in the professional theory of urban design era but have no relation to professional design theory. This was primarily in order to provide a simple, legible framework for comparison – the idea being that this would create an ‘atlas’ of case studies where further examples could be added at will. This was to be a comparative study using a ‘unique heuristic visual method’, made possible by what Baird et al (2010 p.11) regard as a “unique opportunity raised to our generation of urban designers through the use of the latest technological advancements in web-based remote sensing” – this being Google Earth. Thus the Alterations in Scale study team were able to remotely, and objectively measure a huge set of examples: firstly, by way of a comparison of street networks, and secondly; by measuring the edges of the hypothesised ‘sanctuary areas’. Findings & Link to Walkability Alterations in Scale produced a fascinating set of initial results. In their own words, the findings exposed “the natural emergence and evolution of an urban scale over the course of human history” (Baird et al, 2010 p.261). They revealed that the hypothesised 400m scale is shown to exist in cases where professional design theory is absent; the implication being that the rigid frameworks imposed with the advent of professional urban design theory drastically reduced the flexibility and resilience of their respective urban contexts. Indeed, cities right through from antiquity to the periods of time just prior to professional urban design theory were seen with very little exception, to exemplify this 400-meter ‘rule’ (Porta et al, 2014). Beyond this (up to and including the post-modern theories of new urbanism) the distance between main streets in these networks has roughly doubled. The alteration in scale of the main street network may, by extension, imply a similar shift in scale for many of the other crucial ‘sub-structures’ of urban form such as blocks or plots (Ibid). It is this notion that concerns our own study. Our review and subsequent understandings of walkability (see Chapters 1 and 2) point towards the strong correlation between built form and the extent to which an urban environment may be considered walkable. We would therefore suggest that with this documented shift from the more condensed street networks visible in historic examples, we would expect to see the associated levels of walkability change in a manner similar to the findings of Porta et al (Ibid). Clearly, there is scope to continue the work started in alterations in scale, particularly with regards to obtaining further insight into the degrees of adaptability of certain places (Ibid). Walkability after all, features prominently within both placemaking and the wider sustainable urban agenda and establishing a clearer link between walkable form and both scaled and non-scaled 400m cities could provide valuable perspectives on this subject. Continuing Alterations in Scale Research Goals This research aims to develop a collection of evidence demonstrating the influence that the now-confirmed 400 meter principle holds over levels of walkability. The project has examined the degree of walkability across cities of different social, economic, geographical and historic conditions using a carefully selected series of indicators; justification of their usage has been derived from the extensive literature review undertaken by the study team. The evidence will attempt to reveal that the clear point in history at which the 400 meter principle was abandoned coincided with a relative decrease in levels of walkability. Not only will this highlight a perceived weakness in contemporary urban design and practice, but it will point to potential implications within the current place-making and sustainable urbanism agendas.

Research Methodology This research dissertation is a morphological comparison of urban built form; comparing and contrasting certain physical characteristics within a set of case studies in order to determine levels of walkability. The study has put great emphasis on the use of Alterations in Scale as both a theoretical and ideological foundation upon which to build, and efforts have been made to achieve methodological consistency where it has been appropriate to do so. Research for this study was conducted across the summer of 2014 (June/July) by the four constituent authors. In advance of preparing for an in-depth analysis of empirical findings and in order to avoid any ambiguity relating to the outcomes, this following section outlines the methodology used to prepare, collect and process the data. Like Porta et al (2014), the study team have acknowledged the significant benefits afforded to this generation of urban designers through technological advancements within the fields of environmental-remote sensing and geographical information systems. As such, the utilisation of Google Earth was an obvious choice and allowed us to remotely access and produce detailed images of the same cities used in the original Alterations in Scale. The merits of using Google Earth have been increasingly documented over the past decade – particularly within spatial urban analysis (see Clarke et al, 2010). As with Alterations in Scale, the case studies were sorted according to whichever prevailing model or conceptual framework was primarily responsible for urban development. This was done so chronologically, and as such, the case studies are ordered as follows: Historic Cities; Garden Cities; Radiant Cities, and; New Urbanism. It should be noted that historic cases group together examples from Ancient, Medieval, Renaissance, Baroque, and Industrial paradigms respectively. The sampling methodology employed in Alterations in Scale was done so in order to minimise the need for both a “rigorous sampling exercise” and a “detailed theoretical background of every case study” – something that, given the scope of the work, would clearly have placed both resource and time restraints on the original team (Baird et al, 2010 p.11). That said, there was still a clear need to justify the choice of each case study. With measurable examples available for use from virtually anywhere in the world, Baird et al (Ibid) developed a selection process which favoured those urban settlements that have already been well documented and research within published urban design and planning literature. The second piece of criteria was that each case study must not only conform to one of the aforementioned urban design paradigms, but it must still be universally recognised as being representative of this particular form (Porta et al, 2014). There would otherwise be no point in attempting to compare cities which may have developed during a certain paradigm, but have since seen such drastic morphological changes that any evidence of said paradigm has been removed. As such, Continuing Alterations in Scale will use the same group of case studies, bar one exception. The key difference to note is the exclusion of any examples classed as ‘informal settlements’; reducing the total number of case studies available for measurement from 100 to 80. As initial tests were conducted at the start of our analysis, it became clear that the visual identification of certain characteristics (which are central to determining walkability) was going to be problematic. The nature of informal settlements – the examples listed are either shanty-towns, slums, favelas, or townships belonging to the poorer, marginalised sections of society – mean that they have evolved in what appears to be a haphazard, disorganised manner. Visually, such settlements are characterised by a widespread lack of durable housing; semi-permanent structures often obscure any evidence of demarcation between blocks or plots and in some cases, pathways. Therefore any attempts to distinguish between types of road, or in identifying blocks and intersections are likely to lack the consistency required for such a strict comparative analysis. Conducting Measurements The mapping exercise in Continuing Alterations in Scale was conducted using a combination of Google Earth image-based technology, AutoCAD computer-aided design software, and Adobe Creative Suite graphic design tools.

The original Alterations in Scale primarily made use of an in-built measuring tool in Google Earth to determine the distance between sanctuary areas. However, given that this study seeks to measure a substantially greater number of (and equally more complicated) metrics, we were forced to look beyond a simple linear measurement tool. As such, we employed the additional use of AutoCAD in our analysis, owing to its ability to capture technical data within drawings. This allowed for the quick and easy calculation of, for example, shape area (for blocks) and the total length of multiple lines (built frontage calculations). The first step in this process involved sourcing the same background image (at the same scale) for each case study from Google Earth; this was then imported and ‘placed’ within AutoCAD prior to analysis. A crucial task at this point was the re-scaling of each image to ensure the accurate, real-world measurement of street and block dimensions. The next step was to designate the specific sample area within each case study that would serve as our focus – it was decided that the most central node within the previously used Alteration in Scale study area (identified as a light yellow in the accompanying contextual images) would represent a sufficient centre point. In line with well-documented theories regarding optimum distances for neighbourhood design (Porta et al, 2014), a 400m radius circle was then drawn out and around from this point thus establishing an appropriately scaled and sized area for measurement. With an accurately scaled base image to work on and a clearly defined study area, each researcher then ‘traced’ the basic layout of the city, drawing basic block patterns and a hierarchy of lines to denote the local street network. A further consideration that required immediate attention was regarding how our study both defined and approached block identification. At its most basic level of understanding, blocks are the constituent parts of the urban fabric; defined and shaped by the surrounding streets (Frey, 1999). This definition clearly holds true if one considers the layout of many of the industrial cities of the world, where blocks are clearly identifiable due to the rigid grid-structure so favoured at the time. However, even a cursory glance at the street layouts of cities belonging to the garden or radiant city paradigms suggests a situation that is less clear-cut. The defining boundaries in these cases become far more ambiguous and it is here where the definition of the block can often be challenged (Vialard, 2013). In order to avoid ambiguity within our own research and amongst its associated outcomes, Continuing Alterations in Scale has defined blocks as: the areas of urban fabric bordered by connected streets. Crucially, the position of street within the local hierarchy is not restricted to primary and secondary – in some cases tertiary and even quaternary streets may form the boundaries of the block. Following this process, each case study was deemed to be ready for analysis. Walkability Indicators The earlier discussion (see Chapters 1 and 2) regarding walkability in both theory and practice provided much in the way of contextualising our own study and in developing a set of research indicators that would adequately, and accurately, capture levels of walkability. The complex, multi-faceted nature of walkability makes it abundantly clear that no one metric would suffice. Indeed, Sarantakos (1993) notes that this is often the case within heavily analytical research, where multiple indicators are needed to fully quantify the concept. Within research literature, the idea of ‘operationalisation’ refers to translating established principles into a measurable set of variables (Cloke et al, 2004); having carefully considered the existing body of literature, and observing which relevant types of methodologies had been used effectively and consistently (primarily relating to the study of physical elements), it was this process that then led to the identification of the indicators used in our study.

Thus, walkability within Continuing Alterations in Scale has been calculated using the following indicators: 1.Number of Blocks per Study Area In theory, the number of blocks within the designated study area should reveal the existence of characteristics which are themselves highly indicative of a walkable environment. A higher number present within the given study area will indicate a finer urban grain, in turn suggesting higher levels of permeability and street connectivity. For this indicator, researchers undertook a simple count of blocks within the 400 meter radius study area (see above for the process of block definition and identification). Further clarification was needed upon acknowledging that a definitive boundary line would clearly bisect blocks which are positioned at the periphery of the study area. In these instances, the research team took the decision to only include blocks which saw >50% of their area positioned inside of the study boundary. The final count was deemed sufficient for final analysis and synthesis of results due to the consistent size of study area used in each example. 2.Proportion of Coverage against Proportion of Open Space per Study Area Similar to calculating the number of blocks, the extent to which the study area is comprised of built-up area as opposed to open space can reveal characteristics which are again, indicative of a walkable environment. Presence of a higher proportion of built up area is associated with higher density which in turn, sees a direct correlation with both higher levels of mixed-use development and a greater degree of ‘compact’ land-use (Leslie et al, 2007). Furthermore, lower proportions of open space may also suggest less gaps in the continuity of built form; another major influencing factor for walkability. Note that ‘Coverage’ in this instance is comprised of the built-up area within each case study. The final figure was achieved by calculating the total coverage as a proportion of the total study area; producing a percentage for easy comparison during the final research phase. Also noted within each case study is the proportion of Open Space (expressed in the same manner) and a ‘coverage ratio’ for final comparison. 3.Density of Total Intersections per Study Area Calculating the density of intersections (essentially the number of ‘unique street connections’ within a given area) was widely regarded within the literature review as one of the most accurate and effective measures of street connectivity (Leslie et al, 2006; Leslie et al, 2007; Kashef, 2011). Higher densities of intersections were reported to foster greater walkability in that they provide pedestrians with far greater choice in terms of potential routes, shorter journey times, as well as the possibility of more direct routes. Furthermore, this indicator may act as a measure of sidewalk quality and continuity – as per the suggestions within the literature review regarding its appropriateness as a proxy. The methodology used in this study closely follows those examined in the aforementioned literature; focusing on intersections between any category of street within the local hierarchy and, crucially, only those with three connections or more. Density is derived by dividing the total number of unique connections by the total study area, with the final figure expressed in ‘units per hectare’. 4.Density of Intersections (Urban Main/Local Main only) per Study Area It is important to note the distinction between this indicator and the total density figure as discussed above, as research suggests that through this we are able to derive additional and indeed, valuable perspectives, on walkability. Intersections between urban and local main streets are of vital importance within the wider urban fabric. They represent connections where pedestrians are able to better access public transport (more likely to be situated on a main road) and give some indication as to the permeability between neighbourhoods; something that is particularly appropriate given the focus of Alterations in Scale and the concept of main streets as boundaries to sanctuary areas. This indicator measures the total number of unique street connections between Urban Main and Local Main streets (alternatively; the primary and secondary ordered streets within the local hierarchy). Methods used to identify categories of street are a 16

continuation from Alterations in Scale (see ‘Visual Identification’ in Porta et al, 2014). Again this focuses on intersections with three connections or more. Density is again derived by dividing the total number of unique connections by the total study area, with the final figure expressed in ‘units per hectare’. 5.Proportion of Built Frontage per Study Area This indicator is strictly concerned with the built form of each study area – specifically in terms of the relationship between frontages, or facades and the street. Many of urban design’s great authorities (Jacobs, 1961; Cullen; 1967; Gehl 1987) have reinforced the assertion that urban vitality (and by extension, walkability) at the street level requires visual interest. Engagement of the pedestrian through an attractive and diverse streetscape is key in these cases, and there exists a hypothetical ‘critical’ zone between street-edge and building that is fundamental to this theory. As such, this study has calculated the extent of the built frontage for each study area using a ‘4 metre rule’. This refers to the total length of street exhibiting a built front within 4 metres of the street’s edge. The total length of built frontage is then divided by a constant (in this case the study area in m2) in order to produce a comparable figure for subsequent analysis. Methodological Strengths & Weaknesses As per the original Alterations in Scale, the real strength of this type of research lies in its ability to produce a consistent set of case studies that allow for a “concise and equitable comparison” of the data on display (Baird et al, 2010 p.13).The easy dissemination of information is further aided through the extensive use of visuals throughout. We find further validity in the assertions of Baird et al (2010) that the relative straightforwardness and replicable nature of the methodology – along with the existence of literally hundreds of other potential case studies – means that the sample base can continually expand and update; adding more relevant data to the study and further strengthening the associated findings. Indeed, the specific methodologies used to calculate the individual walkability indicators in Continuing Alterations in Scale are just as straightforward and ultimately accessible to anyone with same basic digital tools; indeed the software used will likely be familiar to most urban designers. As such, there is clear potential to establish an ever-growing ‘atlas of walkability’ as theories and paradigms continue to evolve within urban design. Whilst the use of Google Earth has undoubtedly added value to our methodology, we do acknowledge that our reliance upon this key tool brings with it certain limitations. The visual identification of the basic components of urban fabric can be done with relative ease, however certain physical characteristics that might help build a fuller picture of walkability – such as building height, facade transparency, or even block entry points (for use as part of a pedshed analysis) – are impossible to accurately and consistently gauge. Furthermore, this was the reason for the exclusion of informal settlements from our set of case studies. This is particularly unfortunate given the role that this ‘paradigm’ played in establishing the 400 metre principle (as an example of organised complexity; one completely devoid of professional theory). Home to populations with minimal access to automobiles, neighbourhoods within informal settlements are “completely given over” to walkable design (Baird et al, 2010 p.30). A main street in this instance – as it would be in any of the other categories of settlement – resembles more of a broad pedestrian pathway. One could hypothesise the extent to which informal settlements would be shown to be walkable, but without the appropriate analysis this would remain as conjecture. What is true in any case is the possibility that if analysis was possible, that it would offer up truly unique set of perspectives to the debate. This may well change in future with the continued improvements in satellite imaging, and rollout of Google’s Streetview service around the world, hopefully allowing the remote measurement and analysis of urban form in ever greater detail. Finally, we acknowledge a distinct bias towards North American and Western European examples throughout the sample base. As stated previously within the methodology, case study selection was done in order to minimise pressure on the study team and avoid the need for an extensive sampling exercise; only using cities that had been well-documented within existing academic literature. The quality of data could clearly be strengthened through the addition of a greater variety of examples to alleviate the existing bias – a future area of interest given the monumental scale of urban growth could be East Asia. 17

STUDY AREA DISTRIBUTION MAP

LIST OF CASE STUDIES

HISTORIC CITIES

Within the context of Continuing Alterations in Scale, the group of cities that have collectively been referred to as ‘historic’ are those characterised by their respective development in the absence of the automobile. To engage in such broad categorisation may somehow underplay the huge depth in variation amongst them; the examples in question have been continually moulded and shaped by a milieu of social, economic, political and environmental factors throughout many periods of history. Yet it is most appropriate given that it is this shared characteristic that allowed coherent self-organisation that still embodies the desired ‘organised complexity’ of the city (Jacobs, 1961). Indeed, any attempt to examine towns and cities from history will reveal a “remarkable consistency in the fundamental qualities of their progressive development” (Hiorns, 1956); qualities that have somehow been sustained over continuous social and cultural change for close to two and half millennia. The initial designs of these cities subscribed to principles which placed the pedestrian at the fore, with permeable street networks at a limited scale affording pedestrians easy access to both essential services and major civic amenities (Morris, 1994). This is particularly true in the earliest examples of antiquity or the medieval ages, where urban development was often centred on a military institution, market, or public square. Urban development expanded outward from these centres towards a clear boundary – usually either in the form of defensive walls or natural barriers. The renaissance and baroque periods which followed brought with them slight alterations that fell in line with a renewed focus on arts and higher culture; all the while still retaining the eminently functional and practical qualities of the urban fabric. Cities which saw growth during these periods continued to develop in a radial-centric manner from existing civic centres, whilst new settlements (of which there were admittedly few in number) were designed on the principles of convenience, order, and aesthetic value (Hiorns, 1956). This trend arguably continued with the onset of mass industrialisation during the 19th Century; the difference being that the functionality and practicality within the urban fabric was a result of the desire for greater density at close proximity to heavy industry. As stated by Hiorns (Ibid), these were responses to rapid population growth and the subsequent need to provide housing without a full-scale ‘rejection’ of the city. The resultant urban form (such as the grid structures in New York or Glasgow) remains some of the most walkable pieces of city the world over.

GARDEN CITIES

Garden cities refer to the settlements developed according to the ‘Garden City Movement’ and its associated design principles; first hypothesised by Ebenezer Howard at the turn of the 20th Century. The urban form commonly associated with the industrialisation of cities during the late 18th and early 19th centuries – that of the close-grain grid network – is widely regarded as being the optimum for producing the conditions for a liveable, walkable environment. However, the realities of the time might have told a slightly different story; one of overcrowding, of horribly polluted and dangerously unsanitary living conditions. Ebenezer Howard was one of the figures who put forward a solution. Drawing upon the utopian and reformist ideals of the late 19th century, Howard proposed a series of design principles that were to act as ‘relief’ from the prevailing urban conditions (Porta et al, 2014). His vision was to be a complete antithesis of the squalid inner city environments; cities that would provide the holistic benefits of country-side living within an urban context. Central to this movement was a complete redistribution of population, supported by: the careful and deliberate zoning of land-uses (a separation from the negative heavy industry); increased levels of parks and open space, and; greater efficiency through the incorporation of modern transport systems. This last point was particularly important, given that Howard had initially envisaged each of these urban areas as one of many ‘satellites’ clustered around a larger, central city (Goodall, 1987). While in theory this may have seemed an appropriate and logical response (Baird et al, 2010), Howard’s vision was often implemented in “very different places, in very different circumstances, and often through very different mechanisms from those their inventor had originally envisaged” (Hall, 2002 p.2). The resultant form that would emerge from conditions would obviously be quite different to any which had come before it. These modernist attempts at place-making would see low density development far removed and indeed isolated from the varied mix of land uses conducive to walkability.

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RADIANT CITIES

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Within our study, the examples classed as ‘Radiant Cities’ are those which have developed according to the basic principles proposed by Swiss-French architect and planner, Le Corbusier. While these visions were only fully realised in a handful of cases, many cities adopted certain aspects resulting in the distinctive urban forms seen in this section of analysis. Much like Ebenezer Howard before him, Le Corbusier’s vision was one of a social utopia that sought to treat the ills of the previous century through the application of a strict theoretical ordering. Embracing the possibilities afforded through the advancement of building technologies and techniques, Le Corbusier proposed to reorganise previous interpretations of the neighbourhood unit vertically, creating what were to be self-sustaining skyscraper-cities surrounded by open space for leisure and other pedestrian activity. These “vertical representations of Howard’s garden city” (Baird et al, p.22) gave rise to the now ubiquitous phrase: ‘towers in the park'. Efficiency was of great importance to Le Corbusier, and as such, he envisioned each neighbourhood being connected in a rectilinear grid by grand, elevated highways that would render the traditional main streets obsolete. This stringent need for a separation of the two elements is undoubtedly one of the defining features of the ‘Ville Radieuse’ concept, perhaps exemplified by Le Corbusier’s rejection of calls to search for a more appropriate balance between traditional urban forms and the growth of modern technology and transport (Porta et al, 2014). Yet it is this disconnect between the built form and its surroundings that still defines the radiant city ideals. Devoid of human scale, the towers in the park became isolated; the space around them becoming akin to wasteland, “shunned by the public” (Kunstler, 1994 p.79).

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This final grouping of examples belongs to an urban design movement created in response to the perceived failings of modernist principles associated with the likes of Howard and Le Corbusier; having been championed over the past several decades by figures such as Anders Duany and Elizabeth Plater-Zyberk. Although new urbanism’s roots can be traced back to the 1970s and 80s, it was not until the early 90s that a collective of likeminded planners and designers came together to draw up an agreed set up principles for the movement to adhere to. At its core was a desire to counteract the ‘urban disinvestment’ and widespread sprawl seen in previous movements, and instead create urban environments and indeed, places, that are above all, liveable. Central to the practice of the new urbanists is the championing of both higher densities and strict design controls over form – whilst there is not an explicit aim to exclude the automobile by design, the movement does “espouse a pedestrian-first approach” (Baird et al, 2010 p.29). Settlements designed according to strict new urbanist principles should, in theory, have high levels of walkability. Highly designed, comfortable streetscapes exhibiting activated frontages and an abundance of mixed use developments are all very characteristic of the new urbanist approach. Yet the ardent desire to see a break from the unsustainable, cold design of previous movements exposes a major weakness – that of assuming that the implementation of a further logical framework will work anywhere if slight alterations are made. In other words, the same failures that modernism held on to (Porta et al, 2014). Indeed, Alterations in Scale showed that much like the movements that came before it, the scale of the new urbanist’s urban framework too, had increased to twice that seen in historical cities.

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SUMMARY OF RESEARCH

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NO. OF BLOCKS

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Maximum: 249 Minimum: 1

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NO. OF BLOCKS

Historic Cities Q1 37

Garden Cities Q1 5

Radiant Cities Q1 5.75

New Urbanism Q1 18.75

Q3 65.25

Q3 19.25

Q3 17.25

Q3 34

Interquartile Average 48.36

Interquartile Average

13.1

Interquartile Average

Average

36.37

Standard Deviation

40.09

Trendline: F(x)= -1.0021x + 71.947

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Interquartile Average23.75

Analysis undertaken on the number of blocks per study area (a circle of r=400m) revealed some clear trends amongst the set of case studies; much of which was largely in line with our original hypothesis. The highest numbers of blocks were measured against case studies from the historic period, followed by general decreases with subsequent transitions to both Garden City and Radiant City paradigms respectively. Whilst this trend did continue into the realms of New Urbanism to an extent, a far greater proportion of these examples were shown to contain a number of blocks more similar to those witnessed in the Historic Cities. The range within this indicator was revealed to be quite significant, with the smallest count (predictably) found within the group belonging to the Radiant City paradigm (equally shared by Drumul Tabarel in Romania and La Grand Borne in France; both with a count of one block) and the largest within the Historic examples. Even a customary glance at the corresponding graph will indicate just how anomalous this historic example appears to be compared to the remaining case studies (the actual count was 249). This is perhaps explained by the fact that the corresponding city, Grammichele, is itself particularly unique, being one of the only examples of form designed according to a peculiar set of baroque principles â&#x20AC;&#x201C; it was mistakenly believed that the radiocentric planning was akin to the cities of ancient Babylonia (Facaros & Pauls, 2008). Conversely, although appearing quite extreme, the presence of only one block in is fairly characteristic of the built form of Radiant Cities. In terms of the implications for walkability, this data suggests that the scale of urban form clearly increases in line with the introduction of professional urban design theory â&#x20AC;&#x201C; a trend we are able to corroborate with the previous Alterations in Scale (Porta et al, 2014). Lower numbers of blocks present within an area of equal size points to an overall increase in block dimension; ultimately suggesting reduced levels of both connectivity and permeability and the loss of a fine grain street network. Thus, we are able to deduce that walkability in this sense, suffered as result. Although visually suggestive of a negative correlation, it should be noted that basic statistical tests to determine the strength of this relationship have revealed that it is only of a moderate degree. This suggests that simply belonging to a particular design paradigm does not hold enough explanatory power alone to account for the relationship with the number of blocks present.

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PERCENTAGE OF COVERED AREA

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COVERED AREA

Historic Cities Q1 55.20

Garden Cities Q1 13.24

Radiant Cities Q1 15.85

New Urbanism Q1 17.33

Q3 69.99

Q3 29.21

Q3 30.40

Q3 45.86

Interquartile Average 61.23

Interquartile Average

17.78

Interquartile Average

Average

42.95

Standard Deviation

25.37

Trendline: F(x)= -0.7478x + 69.501

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22.69

Interquartile Average 22.32

Much like the data gathered for the number of blocks, the figures revealing the ‘percentage of covered area’ suggest very clear distinctions according to respective design paradigms. The highest percentages of coverage were associated with Historical examples – with an inter-quartile average of approximately 65%. As one might expect, examples built in line with Garden City principles exhibited the lowest overall percentages, where the inter-quartile average in this case was revealed to be just under 18%. The inter-quartile averages of both Radiant City and New Urbanist examples registered slightly higher, both at around 22%. Interestingly, there appear to be a number of cases which exhibit very high percentages of covered area, not only in comparison to other cities within their respective categories, but overall. Seemingly at odds with the main principles of the Garden City movement are two examples from Japan; the Seishin district of Kobe (registering c.86%) and the Tama New Town in Tokyo (c.83%). These measurements may to some extent be explained by our methodology which centres the sample area on a selected node within the street network, thereby reducing the possibility of capturing the open space which (in the case of Garden Cities) is usually found furthest from the block’s edge. However, this would surely account for similar readings in Garden City examples elsewhere. Another similar case is that of the Barbican Estate, a 1970s housing development in central London that was heavily influenced by the Radiant City designs of Le Corbusier. Coverage in this case measured 70%, almost 50 percentage points above the average figure for this category. This is perhaps more understandable when viewed within the context of its immediate surroundings – that of metropolitan London. It may be that given the (relatively) small dimensions of the estate, the sample area has captured part of the high-density ordinary fabric of the wider city – city which has not been subject to the stringent design principles of the Radiant City paradigm. Whilst the findings in the above cases point towards a level of coverage that is acknowledged to be conducive to walkable environments, there are potentially mitigating circumstances which may in turn diminish the extent to which these places may truly be walkable. Aside from these anomalous examples, the majority of cases in the Garden City, Radiant City, and New Urbanist groupings exhibit form which is less likely to result in walkable environments – less coverage suggests that form could also suffer from gaps in continuity, another major influencing factor for walkability. Thus, in this respect, the settlements designed according to professional urban design theory have again shown to be those which are overall less walkable than those where form exists at the traditional 400m scale.

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INTERSECTIONS (OVERALL) (u/ha)

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INTERSECTIONS(OVERALL)

Historic Cities Q1 0.95

Garden Cities Q1 0.32

Radiant Cities Q1 0.3

New Urbanism Q1 0.46

Q3 1.56

Q3 0.66

Q3 0.70

Q3 0.98

Interquartile Average 1.15

Interquartile Average

0.53

Interquartile Average

Average

0.96

Standard Deviation

0.79

Trendline: F(x)= -0.0194x + 1.65

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0.44

Interquartile Average

0.74

Calculating the density of total intersections is widely acknowledged to be an accurate measure of street connectivity – which in turn, is a very effective indicator of walkability. The reason for this is that street connectivity is highly sensitive to urban form and as such is governed by both orientation and dimension of the constituent blocks. It is therefore unsurprising that the results revealed as part of this measure largely reflect the findings and trends seen earlier as part of the ‘block count’. The highest intersections per hectare were measured against case studies from the historic period, followed by a general decrease with transitions to both Garden City and Radiant City paradigms respectively. Whilst the associated chart does point to an overall negative correlation continuing into the group of New Urbanist case studies, a greater proportion of these examples were shown to contain a number of intersections more similar to those witnessed in the Historic Cities. The inter-quartile average for Historic Cities, Garden Cities, Radiant Cities, and New Urbanist settlements was calculated to be 1.2, 0.53, 0.45, and 0.75 respectively. Despite an efficient transport network being of paramount importance to Le Corbusier’s model, our analysis has revealed that in the majority of cases, the form within Radiant Cities exhibits characteristics that are quite contrary to this. Main street lengths and blocks are simply scaled too large to afford any sense of permeability or connectivity (and by extension, walkability) – all of which is compounded by a lack of penetration into the blocks themselves. A particularly damming finding for the Radiant City movement is with regards to Chandigarh. Chandigarh is a city in northern India that still stands as a physical embodiement of the Radiant City concept; a ‘puritanical’ representation of Le Corbusier’s ideas, having been fully planned and implemented the architect himself (Porta et al, 2014). Within our study, Chandigarh scored the second lowest of all case studies in intersection density – in other words, one of the most accurate physical manifestations of a professional urban design theory is one of the least walkable environments documented. Although this indicator can only build a partial image of the true level of walkability, it is interesting to note the relative gap that exists between Historic Cities and New Urbanist settlements given that the attainment of walkable environments is one of the principle tenets of New Urbanist ideology.

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INTERSECTIONS (MAIN URBAN & LOCAL) (u/ha)

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INTERSECTIONS(LOCAL & MAIN ROAD)

Historic Cities Q1 0.61

Garden Cities Q1 0.18

Radiant Cities Q1 0.13

New Urbanism Q1 0.21

Q3 1.12

Q3 0.33

Q3 0.26

Q3 0.68

Interquartile Average 0.86

Interquartile Average 0.26

Interquartile Average

Average

0.50

Standard Deviation

0.39

Trendline: F(x)= -0.0129x + 0.9604

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0.19

Interquartile Average

0.43

The measurement of intersections (again recorded as density and given in units per hectare) between urban main and local main streets can offer valuable and indeed alternative perspectives regarding the potential walkability of a given area. Given the main street’s role as an ‘edge’ to neighbourhood and sanctuary areas (Porta et al, 2014), we are able examine the extent to which permeability exists both within and between neighbourhoods – another important determinant in walkability. Overall, the same trend that has been documented with each of the previous indicators has again been observed in this instance. The highest number of unique intersections per hectare were measured in Historic City examples (an inter-quartile average of 0.73), with the lowest registered amongst case studies of the Radiant City paradigm (an inter-quartile average of 0.18) – Garden Cities (0.28) and New Urbanist designs (0.43) were ranked third and second respectively. Again, the associated chart shows a clear negative correlation between density of intersections and design paradigms, with basic statistical analysis revealing that the strength of this relationship is greater than that observed in previous indicators for both intersection density and number of blocks (r=-0.31). Overall this serves to reinforce the idea that historical fabrics are inherently more permeable than those designed according to professional urban design theory. Visually, some of the form observed in several of the Radiant City case studies is similar to that found in the industrial cities of the late 18th century – Stuyvesant Town in New York being one such example which appears to conform with Le Corbusier’s exact, rectilinear grid. With corroboration from Alterations in Scale, however, main street lengths have been shown to be in excess of 700m, massively out of scale for a truly walkable environment. Again, exemplifying the lack of connectivity and permeability associated with this particular paradigm. Lower scores seen in the Garden City design paradigm may similarly be due to the propensity of larger ‘looped streets’ served by one connection point on a main street. New urbanism registers a slightly higher average score compared to both modernist design paradigms, in line with a desire to increase walkability by, in part, reducing auto-dependency. The higher prevalence of urban main/local main intersections can point towards greater pedestrian access to public transport; most likely to be located on urban main streets. Despite this however, the average density is still just over half of that of the historic examples.

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PERCENTAGE OF TOTAL BUILT FRONT

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BUILT FRONT

Historic Cities Q1 2.69

Garden Cities Q1 0.32

Radiant Cities Q1 0.03

New Urbanism Q1 0.84

Q3 3.70

Q3 2.18

Q3 1.27

Q3 1.58

Interquartile Average 3.05

Interquartile Average

1.04

Interquartile Average

Average

2.18

Standard Deviation

1.97

Trendline: F(x)= -0.0656x + 4.5116

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Interquartile Average

1.27

With regards to measuring how walkability is influenced by morphology, the existence of a built front is a strong indicator; able to suggest the presence of visual interest and even the extent to which a sense of enclosure might be present – all of which have shown to be characteristic of liveable, walkable urban environments. Built front in this case was calculated by measuring the total street length exhibiting frontage within a 4 metre distance from the street edge. The measure in this case is given as a score (calculated by dividing the total street length by the total study area in m2). This final indicator revealed the same trend that has been consistent throughout analysis; high scores registered against examples from Historic Cities with lesser proportions of built front measured in both Garden and Radiant Cities, followed by a slight increase amongst New Urbanism designs. Inter-quartile averages are as follows: 3.3 (Historic), 1.0 (Garden City), 0.6 (Radiant City), and 1.4 (New Urbanism). Morphologically speaking, such a clear distinction between the historic cases and those designed under a theoretical paradigm is perhaps explained by drastic changes to block typology upon the introduction of modernist designs. In particular, the widespread removal of the perimeter block. Both the Garden City and Radiant City paradigms, although utilising it in slightly different ways, viewed open space as an extremely important component of their respective designs. The implementation of space within the footprint of block designs moved the built form away from the street edge, thereby altering relationship between “the spatial organisation of the private domain and the spatial organisation of the public domain” (Meyer, 2005) – a key balance which has been argued to be crucial for the walkable environment (Gehl, 1987). The higher figures measured against New Urbanist examples are in line with the desire to provide diverse streetscapes and higher density mixed-use developments that feature prominent ground floor activation. Thus we can deduce that New Urbanist examples show a degree of walkability, however this still remains lower than the levels seen amongst Historic Cities.

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Discussion & Conclusions Continuing Alterations in Scale has successfully developed a collection of evidence demonstrating the influence that the ‘400 metre principle’ (Porta et al, 2014) holds over levels of walkability. Having conducted a large scale morphological comparison using a carefully selected set of indicators, we can reveal that cities designed according to very different design philosophies and principles exhibit (through the composition and scale of their respective form) very different levels of walkability. Furthermore, in line with our initial research goals, we have revealed that much like the alteration in scale observed by Porta et al (Ibid), there exists a clear point in the history of urban development that coincided with a relative decrease in walkability. This event, as was the case with Alterations in Scale, was the implementation of professional urban design theory. The analysis of case studies showed a distinct, clear set of patterns that were largely consistent across each of the research indicators. Historical Cities registered the highest scores overall – each in terms of the highest number of blocks per study area, highest amount of coverage, highest street connectivity (measured through intersection density), and highest proportion of built front. This suggests that the qualities afforded through the form of historic cities can produce urban environments that are extremely walkable. Designed before the need to accommodate the automobile, these cities were scaled towards human movement and use – small block sizes allowed easy navigation through a very permeable and well-connected street network, with perimeter blocks (and the associated built frontage) arguably contributing to the vitality of the urban environment. Similarly consistent was the extent to which comparatively lower scores were seen amongst the case studies belonging to both Garden City and Radiant City paradigms. Upon the advent of modernism within urban design, the morphological qualities appear to have changed drastically – as each successive designer attempted to rework the urban fabric in line with their own idealistic vision. Cities from both Garden and Radiant paradigms saw low walkability in terms of the compactness of the urban fabric (gauged by the number of blocks per study area) with Radiant Cities also registering particularly low walkability in terms of both street connectivity and permeability. Crucially, this trend ties in strongly with Alterations in Scale, as it was the subsequent move from the historic paradigm into the realms of professional urban design theory that saw a clear break with a traditional human-scaled framework. With reference to Porta et al (Ibid), the scale of urban framework in modernist cities has at least doubled from the Historic period, and this is quite clearly indicated through our measurements – with main street lengths and blocks that are simply scaled too large to afford any walkable sense of permeability or connectivity. Analysis revealed consistency again with regards to the measurable characteristics of New Urbanist case studies; all of which exhibited higher levels of walkable form than Garden and Radiant City paradigms, but still considerably less than Historic examples. Clearly, this sits in line with the stated goals of the New Urbanists in attempting to simultaneously halt sprawl and avoid replication of the radiant city model through incorporating both higher density and form-based codes. The New Urbanist tendency to look towards history for design inspiration is also clearly evident in the recorded measures for the proportion of built front and number of blocks – clearly indicating attempts to reproduce the well-connected, permeable neighbourhoods of historic cities. We previously noted that one of the strengths of this research was the possibility for more case studies to be added on an ad hoc basis – due primarily to the easily replicable nature of the methodology and the existence of numerous other potential case studies. Going forward, we might advocate a constructive review of certain aspects of the methodology – particularly with regards to the siting of each study area. In Continuing Alterations in Scale, the decision was made to centre each area on a main urban node (as identified in Alterations in Scale). However, following the analysis, it was noted that neighbourhoods in some cases (particularly amongst New Urbanist examples) tended to be concentrated away from urban nodes, often in excess of 300 metres. Given that the study area is a 400 metre radius circle; there is a possibility that analysis in some cases may undervalue the associated levels of walkability. For future study, we would therefore also advocate using local nodes as acceptable centre points for study areas. 214

With this dissertation, we hope to have contributed in some way to Porta et alâ&#x20AC;&#x2122;s (2014) calls for further research examining the â&#x20AC;&#x153;logic and principles of what generates a more adaptable, hence resilient, urban fabricâ&#x20AC;? (Ibid, p.17). Through an examination of form, we have determined that cities designed outside of professional urban design theory are more likely to exhibit built characteristics conducive to walkability than those designed according to both modernist and post-modernist principles. Not only does this again imply the failure of the neighbourhood as a designable entity, but it lends credence to the notion that walkability and the associated form could act as a marker for the flexible, resilient city.

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