Sustainable urban form, accessibility and travel

Contents List of Figures List of Tables Acknowledgments Acronyms

iii v ix xi

1. Introduction 1.1 Objectives 1.2 Hypotheses and approach 1.3 Case study and methodology 1.4 Structure of the thesis

1 4 4 5 6

2. Sustainability and the City 2.1 Sustainable development: a vague and contested concept 2.2 Sustainable urban development 2.3 Sustainable urban form: is there such a thing?

2.4 Veracity, feasibility and acceptability: the three dimensions of dispute 2.5 Strategies to implement a compact city 2.6 The Portuguese strategy 2.7 Final Remarks

9 9 14 17 24 29 33 36

3. Urban form, accessibility and travel 3.1 Urban form and travel: a literature review 3.2 Space and travel: the importance of accessibility 3.3 Commuting impacts of housing and employment relocation 3.4 Final remarks

39 40 55 64 73

4. Methodology 4.1 Research design 4.2 Accessibility – methodological considerations 4.3 Statistical analysis: urban form and travel 4.4 Questionnaire design and sample collection 4.5 Interviews 4.6 Summary

77 77 77 99 104 106 107

5. Commuting in AML: can land use explain the observed travel patterns?

5.1 Travel patterns in Portugal and AML 5.2 What explains the commuting patterns of AML? 5.3 Area-based analysis: commuting in the parishes of AML 5.4 Individual-based analysis: commuting patterns of the residents of AML 5.5 Final remarks

111 112 117 118 128 139

6. Residential mobility in Park of the Nations 6.1 Introduction: the Park of the Nations 6.2 The new residents 6.3 Urban design and housing conditions 6.4 Tenure

143 144 147 151 155

Contents ii 6.5 Residential mobility 6.6 Residential satisfaction 6.7 Final remarks

160 172 178

7. Commuting impacts of the relocation to Park of the Nations 7.1 The impact of the residential relocation 7.2 The impact of the workplace relocation 7.3 Final Remarks

181 182 195 213

8. Conclusion 8.1 Main findings 8.2 Theoretical implications of the research findings 8.3 Limitations and further developments

217 218 223 228

References

427

List of Figures Figure 1.1 – Schematic diagram of Lefebvre’s trilogy Figure 2.1 – Mapping of Sustainable Development Figure 2.2 – World’s ecological footprint by component, 1961-2003 Figure 2.3 – Spatial structure of a typical European city Figure 2.4 – Principles of multimodal urban development Figure 2.5 – Transit Oriented Development Figure 2.6 – PROTAML’s Metropolitan Structure Figure 3.1 – Schematic representation of types of daily urban systems Figure 3.2 – Urban form, accessibility and travel behaviour Figure 3.3 – Potential space-prisms Figure 4.1 – Example of the final location of the parishes’ centroids Figure 4.2 - Examples of impedance functions for gravity-type and cumulative opportunities accessibility measures Figure 4.3 – Relationship between land use, socioeconomic characteristics and travel patterns Figure 5.1 – Car ownership rate in EU15 countries, 1991 to 2002 Figure 5.2 – Car ownership rates in USA and Europe, 1970 to 2000 Figure 5.3 – Car share in the EU15 countries, 1991 to 2002 Figure 5.4 – Modal distribution of the daily trips in AML, 1991 and 2001 Figure 5.5 – Commuting by car in AML, 2001 Figure 5.6 – Commuting by PT in AML, 2001 Figure 5.7 – Histograms of the dependent variables analysed in the area-based statistical models Figure 6.1 – Alternative locations considered for Expo’98 site Figure 6.2 – Location of PN and transportation network of AML Figure 6.3 – Map of the Urban Plan of Expo’98 site (PUZI) Figure 6.4 – Sex-age pyramid of the residents of PN Figure 6.5 – PN Householder’s age Figure 6.6 – Household size and type of the residents of PN Figure 6.7 – Householder’s Education level and Occupation in PN Figure 6.8 – Household’s monthly income and householder’s income in kind Figure 6.9 – Workplace of the residents of PN (active householder and spouse) Figure 6.10 – Sizes of the dwellings built in PN and in the municipalities of AML, 2002 to 2004 Figure 6.11 – Housing capacity index in PN, Lisbon and Portugal Figure 6.12 – Location of the second homes of the households of PN (by distrito) Figure 6.13 – Use of the second homes of the households of PN Figure 6.14 – Proportion of homeowners by dwelling construction year, 2001

2 10 12 18 23 32 35 45 55 57 86 96 101 112 113 114 115 116 116 119 145 145 146 147 148 148 149 149 150 151 153 154 155 156

List of Figures iv Figure 6.15 – Rental agreement types and rent values in Park of the Nations Figure 6.16 – New dwellings built in Portugal and PN by type of promoter, 1994 to 2004 Figure 6.17 – Previous location of PN households Figure 6.18 - Classification of residential mobility reasons Figure 6.19 – Reasons for moving (major groups) Figure 6.20 – Alternative locations considered by the households Figure 6.21 – Unwanted places to live, identified by the households Figure 6.22 – Location factors for the households of PN Figure 6.23 – Actual satisfaction of the households with their current housing situation Figure 7.1 - Commuting distance of the AML residents and PN residents Figure 7.2 – Travel distance from PN to AML Parishes Figure 7.3 - Commuting time of AML residents and PN residents Figure 7.4 - Automobile use in PN Figure 7.5 – Commuting time in AML, 1991 and 2001 Figure 7.6 - Impact of housing relocation on travel distance – two hypothetical situations Figure 7.7 – Residential Location of PN workers Figure 7.8 – Workers’ commuting distance Figure 7.9 – Workers’ commuting Mode Figure 7.10 – Workers’ commuting time Figure 7.11 – Previous workplace of PN workers Figure 7.12 – Impact of the workplace relocation on commuting distance Figure 8.1 – Schematic representation of types of frictionless commuting areas Figure 8.2 – Influence of transportation mode on the extent and location of the frictionless commuting area

157 158 162 166 168 169 171 172 173 183 183 184 185 190 192 198 199 199 200 201 202 224 225

List of Tables Table 2.1 – Compact city characteristics Table 2.2 – Energy efficiency of different transport modes (Great Britain, 1990) Table 3.2 – Relations between urban form aspects and place accessibility Table 3.3 – Global accessibility disparity analysis Table 4.1 – Accessibility measures calculated Table 4.2 - Accessibility specification issues Table 4.3 – Travel speeds used for highways and urban streets Table 4.5 - Classification of AML’s facilities in accordance with their spatial scale Table 4.6 – Classification of accessibility measures according to data requests and travel assumptions Table 4.7 – Dependent variables used in the statistical models of AML Table 4.8 – Socio-economic variables used in the statistical models Table 4.9 – Land use variables used in the statistical models Table 4.10 – Statistical models created for each databank and travel pattern Table 4.11 – List of institutions and agencies interviewed Table 5.1 – Commuting in AML, 1991 to 2001 Table 5.2 – Travel patterns analysed in the area-based statistical models Table 5.3 – Descriptive statistics of the commuting patterns of AML, 2001 Table 5.4 – Land use variables transformed for the statistical models Table 5.5 - Stepwise multiple regression of socio-economic, land use and both groups of variables on the percentage of car commuters by parish Table 5.6 – Stepwise multiple regression of socio-economic, land use and both groups of variables on the percentage of public transport commuters by parish Table 5.7 – Values of R2 for the multiple regression models created between the parishes’ commuting patterns and socio-economic and land use data Table 5.8 – List of the two variables with the highest relative correlation for the models developed between socio-economic and land use variables and commuting patterns Table 5.9 – Socio-economic variables used in the individual-based statistical models Table 5.10 – Commuting patterns of the residents and non-residents of Lisbon, 2003 Table 5.11 – Stepwise logistic regression of socio-economic, land use and both groups of variables on the use of car for the daily commuting of the residents Table 5.12 - Stepwise logistic regression of socio-economic, land use and both groups of variables on the use of car for the daily commuting of the non-residents Table 5.13 - Stepwise logistic regression of socio-economic, land use and both groups of variables on the use of public transport or walking for the daily commuting of the residents Table 5.14 – Stepwise logistic regression of socio-economic, land use and both groups of variables on the use of public transport or walking for the daily commuting of the non-residents

22 25 56 61 81 84 88 93 94 100 102 103 104 107 114 118 118 119 121 124 126 127 129 130 131 131

135

135

List of Tables vi Table 5.15 – Values of Nagerlkerke’s R2 for the logistic models between the commuting mode of residents and non-residents and socio-economic and land use data Table 6.1 – PN Dwellings’ number of rooms Table 6.2 – Housing capacity index in Park of the Nations Table 6.3 – Dwellings sold in PN by type of transaction Table 6.4 – Dwelling prices by type of promoter Table 6.5 – Residential location in 1995 of the AML residents, by municipality Table 6.6 – Previous location of the households of PN Table 6.7 – Previous and actual dwelling type of the households Table 6.8 – Dwelling size difference between actual and previous dwelling Table 6.9 – Previous versus actual dwelling tenure Table 6.10 – Reasons for moving to Park of the Nations Table 6.11 – Accessibility values of the top 5 alternative residential parishes Table 6.12 – Alternative locations considered by the households (municipalities) Table 6.13 – Advantages of the location indicated by the households Table 6.14 – Residential location disadvantages indicated by the households Table 6.15- Locations considered for the location of the future dwelling Table 6.16 – Crosstabulation of Ideal workplace and residential location Table 7.1 – Actual transport mode of the residents of PN Table 7.2 – Stated reasons for using the private car Table 7.3 – Previous and actual transportation mode of the residents of PN Table 7.4 – Impact of the residential relocation in transportation mode Table 7.5 – Relationship between the impact on transportation mode and the time the residents have lived in the current dwelling Table 7.6 – Impact of the residential relocation on commuting time Table 7.7 – Previous and actual commuting time of the residents of PN Table 7.8 – Impact of the relocation on commuting distance Table 7.9 – Residential relocation impact on commuting distance and commuting time Table 7.10 – Residential relocation impact on transportation mode and travel distance Table 7.11 – Residential relocation impact on transportation mode and travel time Table 7.12 – Occupation groups and household income of the sampled workers Table 7.13 – Age and gender of the sample workers Table 7.14 – Percentage of dual-earner households of the sampled workers Table 7.15 – Previous workplace type of PN workers Table 7.16 – Impact on commuting distance by previous workplace type Table 7.17 – Travel time impact of the workplace relocation Table 7.18 – Previous and actual commuting time of the workers (n=270) Table 7.19 – Commuting time impacts by previous workplace type Table 7.20 – Previous and actual commuting mode of the workers Table 7.21 – Transportation mode impact by previous workplace type (n=234) Table 7.22 – Commuting impacts of the workplace relocation, in terms of travel time and travel distance

138 152 153 157 159 160 161 163 164 164 167 169 170 174 175 176 177 185 187 188 188 189 189 190 191 193 194 195 196 197 197 201 202 203 203 204 205 205 206

vii List of Tables Table 7.23 – Commuting impacts of the workplace relocation, in terms of travel distance and transportation mode Table 7.24 – Commuting impacts of the workplace relocation, in terms of travel time and transportation mode Table 7.25 – Worker’s intention to move housing within the next five years Table 7.26 – Future desired residential locations expressed by the workers Table 7.27 – Workers intention to move in relation with their actual commuting distance Table 7.28 – Distance of new residential location in relation to the actual commuting distance of PN workers

207 208 209 210 211 212

Acknowledgments Although the research developed and presented in this thesis is the result of my effort and dedication, I realize its achievement was only possible due to the help and support of several individuals and institutions that I wish to thank. First of all, I want to thank my supervisors, Stuart Cameron and Geoff Vigar, from Newcastle University, which gave me all the support and important and valuable suggestions in the development of my thoughts. I had several doubts throughout these four years, passed through good and bad moments, and their presence and help was constant throughout all this time. Again, thanks for everything.

Also extremely important was the financial support I had from the Calouste Gulbenkian Foundation, which allowed me to locate in Newcastle and support the costs of living and studying in the UK, grating me a PhD scholarship. The support I had from the Faculty of Architecture of the Technical University of Lisbon, where I teach, was also extremely important in achieving my goals, as without the three-year sabbatical I was granted, with the support of the PRODEP programme from the EU, I wouldn’t be able to develop my research in Newcastle. From the Faculty, a special thanks to Prof. Clara Mendes, which gave me all the support in my intention to move to Newcastle to develop my PhD, and always showed a genuine interest in my work.

At a more institutional level, I need to thank the Transporlis project, which gave me the data of public transportation network, and the Metropolitan Area of Lisbon, which gave me data of the facilities of AML. I also want to thank Prof. Nunes da Silva, from Instituto Superior Técnico of the Technical University of Lisbon, which gave me additional data on the facilities of AML. All these data was essential to calculate the accessibility indicators presented in this thesis. Also regarding secondary data, I wish to thank Susana Castelo, from TIS, which helped me with the data of AML’s Travel Survey, namely explaining me the structure and organization of the data files.

Throughout these years of research, I also had helpful suggestions from several people I wish to thank. From Newcastle University, I want to thank Prof. Frank Moulaert and Prof.

Patsy Healey, which gave me precious criticisms and suggestions to my thesis in a preliminary stage and also at a more advanced stage of my work. From Portugal, I want to give a special thanks to the students who helped me with the application of the residents’ survey, without them it would become a Hercules task. I hope they have learnt something with it, and wish them all the success for their careers as Architects and Planners. A special thanks to Nuno Raposo, who helped me in several occasions of my research, not only challenging my thoughts and ideas but also being excited with my results.

Finally, I wish to thank my family and friends (you know who you are), who make my life better and easier with their companionship and friendship. Some things seem to last forever, and that is really nice to feel. To them, I wish all the best in the world.

Acronyms AML – Metropolitan Area of Lisbon (“Área Metropolitana de Lisboa”) AMTL – Lisbon’s Metropolitan Authority for Transportation (“Autoridade Metropolitana de Transportes de Lisboa”) CSD – United Nations Commission on Sustainable Development ENDS – Portuguese National Strategy for Sustainable Development (“Estratégia Nacional para o Desenvolvimento Sustentável”) EU – European Union EU-ETS – European Union Emission Trading Scheme FFS – Free Flow Speed GHG – Greenhouse Gases IA – Impact Assessment IEA – International Energy Agency INE – National Institute of Statistics (“Instituto Nacional de Estatística”) IPCC – Intergovernmental Panel on Climate Change LEM – Location Efficient Mortgage LOS – Level of Service NU – New Urbanism PMT – Personal Miles Travelled PNAC – National Plan for Climate Change (“Plano Nacional para as Alterações Climáticas”) PT – Public Transport SDS – European Union Sustainable Development Strategy TOD – Transit Oriented Development UAE – United Arab Emirates UGB – Urban Growth Boundary UN – United Nations UNEP – United Nations Environment Programme UNFCCC – United Nations Framework Convention on Climate Change USA – United States of America VKT – Vehicle Kilometres Travelled VMT – Vehicle Miles Travelled

1. Introduction Sustainable development constitutes one of the main challenges of the world today, despite the intrinsic vagueness of this concept. Cities are seen as major contributors to the actual high levels of energy consumption and pollution, and to counteract this situation, sustainable urban development strategies are being pursued and implemented in cities around the world. In particular, the actual urban form of cities is seen as highly unsustainable (Ewing, 1997) and so, following the designated Re-Designing the City model (Haughton, 1997), a sustainable urban form is being promoted, with three transportationbased objectives: access by proximity, inversion of transportation hierarchy and demand reduction (Wheeler, 1998). Access by proximity implies to reduce distances between origins and destinations, by making housing and activities closer to each other. The inversion of transportation hierarchy constitutes a new paradigm in transportation planning, by which non-motorized modes should be given priority to motorized modes, and public transport should be given priority over private transportation modes. In accordance, in the new transportation hierarchy the pedestrian has the primacy, followed by the bicycle, public transport and finally the car. Demand reduction is strictly connected with the demand for travel, by which it is expected that the amount of travel reduces as a result of the new urban form, which may be achieved as a result of shorter travel distances but it can be achieve also by other means as telecommuting for instance.

In broad terms, a sustainable urban form constitutes a dense built environment, in which different land uses co-exist in short proximity, where people can live, work, shop and recreate without the need of a car (Breheny, 1992a, Haughton and Hunter, 1994, Jenks et al., 1996, Jenks and Dempsey, 2005, Williams et al., 2000). In other words, it constitutes an urban environment in which the majority of daily needs can be fulfilled by walking and cycling or by public transport, and so the use of the car becomes an option instead of a necessity. Therefore, mobility patterns are seen as a key parameter of the sustainability level of a city, in which the coordination of land use and transport is essential to spur a sustainable mobility pattern.

This sustainable urban development strategy is normally designated in a European context as ‘compact city policy’, and is based on notions of distance, i.e. on a Euclidean conception of space, by which proximity of origins and destinations becomes an essential feature of urban space. This need to reduce distances justifies the higher urban density and mixture of land uses, which in turn will increase the accessibility of places, in order to achieve sustainable mobility behaviour, i.e. less car usage and smaller travel distances.

However, sustainable urban form is being challenged in three different dimensions: its veracity, i.e. the ability of the sustainable urban form to alter travel behaviour, its feasibility, i.e. the possibility to implement such strategy, and its acceptability, i.e. the acceptance of individuals to live in such urban environments and have such mobility behaviour (Breheny, 1992b, 1997, Gordon and Richardson, 1997, Neuman, 2005, Senior et al., 2004, 2006).

Indeed, travel behaviour depends on the land use and transportation characteristics of a place, but also on the social characteristics and responsibilities of an individual (Jarvis et al., 2001), and the assumption that travel behaviour will change as a result of a transformation of urban environment can be seen as a simplification of a complex phenomenon (Williams, 1

2 Sustainable Urban Form, Accessibility and Travel

2005b). In this sense, the veracity of the sustainable urban form arguments is challenged as the causality of the relationship between land use and travel is under dispute. Two main arguments support this doubts. First, the relationship between land use and travel tends to be weak, and socio-economic and attitudes towards travel are normally better explanatory variables than urban form variables. Secondly, a statistical relationship between two variables does not prove causality, only shows association, and often different individuals are used in the statistical modelling, raising doubts about the cause-effect of urban form over individual preferences towards travel.

Indeed, one can question how and why land use might influence travel behaviour. In this thesis, we followed Lefebvre (1991)’s conception of space, which describes space as a trilogy of conceived, perceived and lived space. In accordance, travel behaviour is considered an expression of the lived space of individuals and urban form the conceived space. Accessibility is used as a surrogate for the perceived space, which is, in this theoretical framework, as important as the other two dimensions of space. Therefore, it is assumed that the observed travel behaviour is a result of a decision-making process, influenced by the conceived space, i.e. urban form, but also by the perceived space, i.e. accessibility – see Figure 1.1. As urban form reflects land use and transportation conditions of a place, it has a clear influence on the accessibility of a place, which in turn will change the way an individual perceive a certain space, and so its travel behaviour might change in accordance. In other words, it is assumed that urban form has an indirect effect on travel behaviour, by altering the accessibility of a place, which becomes essential to understand and explain travel behaviour. Accordingly, we assume that the choice of transportation mode depends, amongst other issues, on the accessibility conditions given by different transportation modes in a certain place and specifically on how they compare to each other.

In order to express these differentiated space-based accessibility conditions of a place, we present the concept of ‘global accessibility disparity’, by disaggregating and comparing accessibility by car and non-car at the regional and local scales, and use it as an additional independent variable to explain commuting patterns.

Figure 1.1 – Schematic diagram of Lefebvre’s trilogy

Introduction 3

Nevertheless, the addition of accessibility as one explanatory variable of travel behaviour does not help to prove causality between land use and travel. It only incorporates a measure of the perceived space, by expressing something that is not directly seen but felt and perceived in a certain place. In order to prove causality, changes of an individual’s travel behaviour must occur as a result of changes in land use and accessibility conditions of the individual’s residential place and/or workplace. This requires a new methodology for the research on the relationship between urban form and travel, which has to be based on longitudinal or quasi-longitudinal analysis, instead of cross-sectional analysis of different individuals living or working in different places.

In this thesis, in order to explain commuting behaviour, we developed cross-sectional and quasi-longitudinal analyses. Commuting is an important and structural feature of travel, but represents only a fraction of the total travel of an individual. Nevertheless, commuting is simultaneously a cause and a consequence of the choice of residential and workplace location, and so it might be argued that although a sustainable urban form might create sustainable impacts on non-work travel, a more sustainable commuting pattern should also be an intrinsic objective of a sustainable urban development policy. Moreover, as we want to evaluate travel impacts of a residential and workplace relocation through a quasilongitudinal quantitative methodology, it was assumed that an individual could easily describe his/her actual and previous commuting pattern, but not his/her total travel pattern.

The evaluation of more detailed travel behaviour would imply to analyse travel diaries of the current and the previous location, which would require a longitudinal study, carried out at two different moments of time. This approach was not compatible with the time span we had to develop fieldwork, and because we focused on individuals that had already moved residence or workplace to a new place, the only option was to develop a quasi-longitudinal research. Therefore, although the data collection method prevented a more comprehensive travel data analysis and we recognise that only a fraction of total travel impacts are analysed by focusing only on commuting, we see commuting behaviour as an important sustainable mobility indicator.

Moreover, besides the analysis of commuting impacts created by residential and workplace relocations, we also analyse residential mobility reasons. This analysis is aimed at understanding why someone chooses to live in a certain urban environment, especially to understand the importance of commuting and workplace location in that choice process. As we want to contribute to the discussion of veracity and acceptability of sustainable urban form, we choose a case study that might represent a good example of a sustainable urban environment, i.e. a dense, mixed-use and accessible place, and analysed residential mobility reasons as well as commuting impacts of both residents and workers of the site.

Furthermore, by identifying alternative locations considered by the residents, it is possible to characterize their search pattern in terms of urban environment features, and understand which features are essential in their search pattern.

Additionally, we also performed a prospective analysis of residential mobility, which discloses future desired housing locations, in order to understand if the dense, mixed-use and accessible place constitutes an attractive and desired residential location for the workers of the site. The combined analysis of both parameters allows evaluating the acceptability of the sustainable urban form debate, which is based on the assumption that people are willing to live at short distance of their workplace and fulfil the majority of their daily needs at the closest facilities. Therefore, we try to compensate the restriction of analysing only commuting with an analysis of both residential mobility reasons and future residential

4 Sustainable Urban Form, Accessibility and Travel

intentions, which may help to uncover the relative importance of land use and accessibility in explaining travel behaviour, when compared with the residential location choice pattern, which can by itself explain part of the commuting behaviour of an individual.

1.1 Objectives The research performed and presented in this thesis has three major objectives. First, it tries to contribute to the knowledge and understanding of the relationship between land use and commuting, by including accessibility as a complementary explanatory variable to urban form and socio-economic variables. Secondly, it intends to test the causal relationship between land use and commuting, and so the causality relationship of sustainable urban form and travel, by uncovering commuting impacts created by residential and workplace relocations to a ‘sustainable urban centre’, i.e. a dense, mixed-use and accessible location.

Thirdly, it intends to analyse the acceptability of individuals to live and work in close proximity, by exploring the importance of commuting distance and commuting time in the residential choice process of households whose residential place or workplace is a sustainable urban centre.

1.2 Hypotheses and approach This research assumes a process-oriented behavioural approach, which means that the focus is on decision-making factors and in the transformation process of a spatial system rather than in the explanation of the form or the final product. This approach “incorporates the belief that the physical elements of existing and past spatial systems represent the manifestations of a myriad of past and present decision-making behaviours by individuals, groups and institutions in society" (Golledge and Stimson, 1997, pp. 6). Accordingly, it assumes a bounded rational human behaviour rather than the traditional economic human behaviour that assumes a rational decision-maker, normally associated with the concept of maximization (of utility or profit).

Based on a deductive approach, we try to answer two main questions: a) Besides the influence of socio-economic characteristics, does urban form influence commuting behaviour? And given that urban form has a clear influence on accessibility, is there a strong relationship between accessibility and commuting? b) Does polycentric urban development contributes to a more sustainable commuting behaviour? If so, the creation of a new mixed-use, dense and accessible centrality should have increased the sustainability of commuting behaviour of residents and workers, i.e., less car usage and smaller commuting distances.

Implicit in these two questions, several hypotheses raised in the literature are being tested in this thesis: a) The designated self-selection hypothesis (Kitamura et al., 1997, Boarnet and Sarmiento, 1998, Boarnet and Crane, 2001), that posits that the choice of residential location is partly a result of the preferred transportation mode, and so the observed differences in travel patterns are not directly attributed to different land use characteristics, but to socio-economic characteristics and attitudes of the individuals.

Introduction 5

b) The causality relationship between land use and travel. As mentioned before, doubts have been raised in the results of research on the relationship between urban form and travel, on the basis that a statistical relation does not prove directly a causal relationship, as different individuals are being compared in standard cross-sectional studies (Handy et al., 2005). c) The hypothesis of the positive utility of commuting (Hupkes, 1982, Redmond and Mokhtarian, 2001), that posits that individuals do not want to reduce commuting towards zero, but benefit from some time-distance from home to work in order to ‘switch off and switch on’ between activities, revealing therefore a certain tolerance towards commuting (Rouwendal and Nijkamp, 2004). d) Strictly related with the last one, the hypothesis of the existence of a critical isochrone and associated frictionless commuting area (Getis, 1969, Van Ommeren et al., 1997), by which the residential search pattern is not aimed at reducing commuting, but to keep it within a certain acceptable travel time. Implicit is the hypothesis that, for a household, commuting time is more important that commuting distance or commuting mode.

1.3 Case study and methodology In order to answer these two main questions and test the related hypotheses, Lisbon Metropolitan Area (AML) was used as case study, and ‘Park of the Nations’ (PN) as the example of a new mixed-use, dense and accessible centrality created with the clear objective of reinforcing the polycentric structure of the metropolitan area. AML constitutes an interesting case study, not only due to the explicit polycentric urban development policy, but also because Portugal is showing a significant increase in car ownership rate and car usage, in part due to the socio-economic development that is being felt since the adhesion to the European Union in 1986. Furthermore, as a southern European city, Lisbon is a relatively dense city, which grew at a very fast rate in the 1960s and 1970s, as a consequence of a massive rural-urban migration, and so its suburbs are, in the vast majority of cases, places with clear deficiencies in terms of urban facilities and infrastructures, including a deficient public transport system. Therefore, the polycentric development policy tries to give a sense of ‘urbanity’ to these places, and is based on the same assumptions of sustainable urban form arguments, namely that by increasing proximity between housing and workplaces, promoting mixed-use environments and increasing therefore non-car accessibility of these new centres, a more sustainable mobility pattern is possible.

The methodology of this research has two sections, in accordance with the questions raised in this thesis. Firstly, in order to evaluate the relationship between land use and commuting, including the influence of accessibility, cross-sectional statistical models were developed for residents of AML, using data from the Census 2001 disaggregated at the parish level, and AML’s travel survey of 2003, available at the individual level.

Accessibility was measured at the parish level, and disaggregated by car and public transport, considering travel to work at the morning peak hour. Car and public transport commuting were used as dependent variables of the models, and for each one, three different groups of independent variable were uses: socio-economic variables, land use and accessibility variables, and finally both socio-economic and land use and accessibility

6 Sustainable Urban Form, Accessibility and Travel

variables. This method allows the comparison of the explanatory power given by each group of variables, and the evaluation of the added explanatory power obtained by the introduction of land use and accessibility variables to explain car and public transport commuting.

Secondly, to evaluate the contribution of polycentric urban development to sustainability, the impact of residential and workplace relocations were evaluated in the case of Park of the Nations in Lisbon. In this case, a quasi-longitudinal analysis was performed, applying a questionnaire containing retrospective questions of the commuting patterns before and after the move to Park of the Nations. The residents’ data was obtained through a face-to-face questionnaire, and the workers’ data through a self-completion questionnaire, both applied during 2005. The quasi-longitudinal feature of the data allows testing the causality hypothesis of the influence of land use on travel, once the data reveals commuting behaviour of the same individuals at two different moments in time, when they lived or worked in different places. In addition, as the questionnaires contain prospective questions regarding the desired residential and workplace location, and the evaluation of the respondent’s satisfaction with his/her current residential and workplace location, it is also possible to test the hypothesis of the positive utility of commuting. Finally, the combined analysis of commuting impacts can test the existence of a critical isochrone and associated frictionless commuting area, by understanding the importance of commuting time over commuting distance or mode, and also through the desired residential location, given the new workplace location.

1.4 Structure of the thesis This thesis starts by presenting the concept of sustainable development, highlighting the vagueness and contestation around it. We then focus on the relevance of sustainability to urban development, including the four theoretical models for sustainable urban development. The concept of a sustainable urban form is presented and questioned, by describing the main features of the contemporary cities of the western world, and the factors that explain their dispersion and fragmentation. The concept of the compact city is then presented in more detail, once it constitutes the archetypal of a European sustainable city.

Within this thesis, it is proposed that this concept should be reframed as a ‘multimodal accessible city’, stressing accessibility as a key feature of what might constitute a sustainable city. Afterwards, we present the three main dimensions of dispute regarding sustainable urban development, namely the veracity, feasibility and acceptability of these policies. The chapter concludes by presenting the main existent strategies to implement a compact city, namely the European and American approach, and in more detail the Portuguese strategy for sustainable development and the urban instruments and policies with impact on the Metropolitan Area of Lisbon.

The succeeding chapter presents a literature review on the relationship between urban form, accessibility and travel. The main dimensions of land use with influence on travel are presented in detail, namely settlement size, urban structure, relative location of residence, intensity of land use and mixing of land use, and other land use variables with influence on travel are also only briefly presented, once they constitute small-scale approaches to land use, which goes beyond the focus of this thesis. Afterwards, the concept of accessibility is presented, and its relation to land use and travel is exposed. Within it, the concept of accessibility disparity is also presented, and it is proposed that it should be by disaggregated

Introduction 7

not only regarding transportation mode but also distinguishing between regional and local accessibility. After this discussion of accessibility, we present a literature review of the relationship between accessibility and travel. Finally, and has we want to explore the impacts created by housing and employment relocations, we present a literature review on the commuting impacts of housing and employment relocations in cities of the western world.

In the following chapter, we present the methodology used in the research, namely the research design, the statistical procedures used, the questionnaire design and sample collection methods, and the interviews carried out in the fieldwork. Due to the importance we give to accessibility as a complementary explanatory variable, the methodology chapter also exposes in some detail accessibility measures and methods for their calculation, including the key issues the researcher has to consider when faced with the calculation of an accessibility index: specification, calibration and interpretation of the indicator. Besides the possible methods for each one, we describe the methods used in this research for measuring accessibility of the parishes of AML. In the following three chapters – chapters five, six and seven – the empirical data analysis is presented and the findings discussed. Chapter five is dedicated to the commuting patterns of AML, and the statistical models developed to explain them, by including socioeconomic, land use and accessibility variables as explanatory variables. Commuting by car and commuting by public transport are analysed separately, and the findings show that they are explained by different variables. In general terms, car commuting is mainly a socioeconomic driven phenomenon and public transport commuting is a land use explained phenomenon. Accessibility was found important as a complementary explanatory variable in the models.

Chapter six is focused on the residential mobility pattern of the new residents of Park of the Nations. The urban characteristics of site are presented in some detail, as well as a brief history of the creation of this new centrality in AML. The analysis reveals reasons for the move and residential location choice factors, as well as alternative and undesired residential locations considered by the residents. A final analysis of the current residential satisfaction of the residents is presented, considering their actual workplace location. The chapter ends by giving an overview of the residential mobility pattern, which showed a clear desire of living in a newly built urban environment with several recreational facilities, relatively close to the residents workplace, with good car accessibility and parking facilities, but not necessarily with good public transport accessibility.

In chapter seven are presented the commuting impacts created by the residential and workplace relocation to Park of the Nations. Unlike assumed in the sustainable development policy, the residents commuting impact in terms of transportation mode was mainly negligible, as the vast majority commuted by car in the previous location and the residential location did not alter their commuting mode. However, there was a clear reduction of both commuting distance and time as a result of the residential relocation, and so it might be seen as relatively sustainable impact, once commuting distance is clearly associated with energy consumption and pollution. The workers of the site however had a different commuting impact. Despite being less car users than the residents, the workplace relocation increased the percentage of car commuters and increased travel distance for nearly half of the workers, and so the workplace relocation had an unsustainable commuting impact. The chapter ends by presenting the future residential location intentions of workers, which revealed that only a small fraction is considering relocating to a place close to their

8 Sustainable Urban Form, Accessibility and Travel

workplace, and the vast majority which intends to relocate wants to live in a place ‘close, but not too close’ of their workplace, supporting therefore the frictionless commuting area hypothesis.

The last chapter of this thesis presents an overview of the findings of the three empirical chapters and some theoretical implications that can be drawn from the findings. In general terms, we state that travel behaviour is influenced by land use and accessibility, and that a polycentric urban development policy is important but not sufficient, by itself, to spur a sustainable mobility pattern. Individuals seem to obtain a positive utility from commuting, especially in terms of commuting time, and so the creation of centres in which they can live and work does not seem to be enough to alter their residential search pattern and consequently their commuting behaviour. Important and essential complementary policies are the promotion of an effective public transport network design and coordination system, and ‘stick’ measures to dissuade the use of the car, following a ‘carrot and stick’ transportation policy strategy. The thesis ends by presenting the major limitations of this study, and possible further developments of this research subject.