Marcial Echenique

Growing Cities Sustainably: Does Urban Form Really Matter?

Problem, research strategy, and findings: It is commonly asserted that so-called compact development is the urban form most able to sustainably accommodate growth by reducing travel distances and conserving land, but credible supportive evidence remains limited. This study rigorously and realistically tested the relative performance of spatial options over the next 30 years for three distinct kinds of English city regions. Statistical models first forecast the behavior of people within interacting markets for land and transport. These outputs were then fed to established simulation models to generate 26 indicators measuring the economic efficiency, resource use, social impact, and environmental impact of the spatial options. This permitted an explicit comparison of the costs and benefits of compact against sprawling urban forms for these regions. While the prototypes (i.e., compaction, sprawl, edge expansion, and new towns) were indeed found to differ in their sustainability, no one form was clearly superior. Rather, the change to “white collar” lifestyles and associated population growth dominates the impacts on the natural environment and resources, far overwhelming those attributable to spatial urban form. Takeaway for practice: Urban form policies can have important impacts on local environmental quality, economy, crowding, and social equity, but their influence on energy consumption and land use is very modest; compact development should not automatically be associated with the preferred spatial growth strategy. Research support: The research was funded by the UK Engineering and Physical Science Research Council.

URBAN AND REGIONAL STUDIES AT THE MARTIN CENTRE: ITS ORIGINS, ITS PRESENT, ITS FUTURE

In this paper the author traces the origins of the Martin Centre work in urban and regional studies back to the geometrical explorations of grids and buildings by Sir Leslie Martin and Lionel March. That work encouraged the author and his colleagues to look for a deeper understanding in order to forecast how people would use proposed layouts for cities, and thus evaluate them. The sources of understanding came from other disciplines such as economics, engineering, geography, and planning which, combined with the physical understanding of the buildings, towns, and networks, provided the basis for the development of comprehensive models of cities and regions. This understanding is embodied in the operational software of the MEPLAN model which is used extensively in practice. The author concludes by taking stock of what has been achieved and argues for the need to improve the knowledge of the supply aspects in the urban system and to simplify the operations of the model without losing its comprehensiveness.

Land Use, Transport, and Carbon Futures: The Impact of Spatial Form Strategies in Three UK Urban Regions

Land-use and transport systems are an important determinant of carbon dioxide emissions from urban regions. It is often asserted that urban compaction is the spatial policy best able to constrain travel and emissions, but evidence supporting this assertion is limited, particularly with respect to the combined emission from transport and land use. Here, using land-use–transport interaction models, a residential dwelling type model, and transport and emission models, we forecast and assess carbon dioxide emissions from transport, dwellings, and commercial space to 2031 for a range of spatial strategies realistically investigated for three English regions of decreasing size (the Wider South East region, Tyne and Wear, and Cambridge). Our results reveal that compaction can reduce emission relative to other spatial scenarios but that the differences are small, about 5% between extremes, an order of magnitude less than emission growth observed over the trend period. Form has more influence for settlements where the pattern and proximity of employment, housing, and services can make cycling, walking, and public transport provision more feasible. We conclude that pricing and technology measures offer better prospects for combating the growth in carbon emissions of urban regions, but that the type of urban form delivered is likely to be a significant determinant in the type of clean energy technology that can be implemented.

A recursive spatial equilibrium model for planning large-scale urban change

This paper presents a recursive spatial equilibrium model for urban activity location and travel choices in large city regions that anticipate major development or restructuring. In the model, producer and consumer choices that adjust quickly to stimuli reach temporary equilibria subject to recursively updated activity churn, background trends, estate development, and transport supply. The city regions performance at each time horizon affects the recursive variables for the next. The model builds on field leaders of urban general equilibrium, spatial interaction, and nonequilibrium dynamic models, and offers theoretical and practical improvements in order to fill an important gap in long-range urban forecasting. Linking the equilibrium and nonequilibrium models enables the simulation of path dependence in urban evolution trajectories that neither could produce in isolation. At the same time the model provides quantification of impacts of different policy interventions on a consistent basis for a given time horizon. The model is tested on the main archetypal urban development strategies for large-scale development and restructuring.

A disaggregated model of urban spatial structure: theoretical framework

This paper describes a disaggregated model of urban spatial structure which combines the framework provided by the macroscale approach of social physics, to which most models developed to date belong, and the advantages derived from the use of the microscale approach provided by economic theory. The model attempts to integrate both approaches by means of the use of maximum entropy techniques together with concepts from microeconomic theory. The former provides an operational basis for the model, while the latter provides a theoretical explanation of the process. At a general level the model introduces the addition of a land market submodel and a transport submodel to the framework provided by Lowry (1964). At a more detailed level the model transforms the employment in the city into economic sectors, socioeconomic groups, and income groups. This allows for the conception of the urban spatial structure in terms of a market where transactions take place between buyers and sellers of goods. The disaggregated model presented here has been designed to provide a large number of variables which can be manipulated and controlled as part of policy decision making and planning analysis—this includes, for example, the normal planning controls such as density restriction and changes in the location of manufacturing, government, and agricultural employment. Also, the effect of changes in the costs of transport (car prices, fares, and routing) can be analysed. Taxes and subsidies on income, housing, and housing interest rates can be manipulated within the model.

LUISA: A Land-Use Interaction with Social Accounting Model; Presentation and Enhanced Calibration Method

Random utility modelling has been established as one of the main paradigms for the implementation of land-use spatial interaction (LUSI) models. We present a detailed formal description of a LUSI model that adheres to the random utility paradigm through the explicit distinction between utility and cost across all processes that represent the behaviour of agents. The model is rooted in a social accounting matrix, with the workforce and households accounts being disaggregated by socioeconomic type. Similarly, the land account is broken down by domestic and nondomestic land-use types. The model is developed around two processes. Firstly, the generation of demand for inputs required by established production; when appropriate the implicit production functions are assumed to depend on costs of inputs, which give rise to price-elastic demands. And, secondly, the spatial assignment of demanded inputs to locations of their production; here sequences of decisions are used to distribute demand both spatially and aspatially, and to propagate costs and utilities of production and consumption that emerge from imbalances between supply and demand. The implementation of this generic model is discussed in relation to the case of the UK. The model has been developed for testing the sustainability of integrated economic, spatial development policies, and output information for estimating urban form and the potential for decentralised technologies. The inputs include area-wide socioeconomic forecasts and the allocation policy of urban land. The outputs include the spatial allocation of activities and prices of labour, goods and services, land, and floorspace. They are combined with the land inputs to estimate the changes in the density of urban form and activities. These outputs can then be used to estimate the demands for infrastructure services and the potential for decentralised infrastructure supply. We focus primarily on the calibration process and its methodological implications, including a method of refining the calibration and demonstrate how this improves the spatial representation of the utility of land.

Mobility and income

The relationship between income and mobility The total income of a country is normally measured by the gross domestic product (GDP), that is to say, by all economic activity, measured in money terms, taking place in a country during a year (ONS, 2004a). Similarly, physical mobility can be measured by the total amount of passenger and freight travel, measured in passenger miles (DfT, 2003a) and tonne miles (DfT, 2003b), respectively, taking place in a country during a year. As can be seen in figure 1 there is a clear relationship in the UK between the growth of income and the growth of mobility. This finding has been confirmed throughout the world (Schafer and Victor, 1997).

SIMPLAN: A SIMplified PLANning Model

The SIMPLAN modelling suite comprises four modules for informing the process of city planning. The first module (called TAM) is concerned with analysing the evolution of the spatial structure of a city. The second module (called RLM) is an econometric residential location model that uses average housing rents as part of the generalised cost in a gravity-type allocation function and currently deals with work trips. The work trips are then split by mode using a multinomial logit modal split model (called MSM), which forms the third module of SIMPLAN. After appropriate calibration, SIMPLAN can be used to test alternative planning policies for a future/horizon year, with appropriate employment, dwelling floorspace, and transport inputs. The fourth module (called ASM) is concerned with assessment of alternative planning policies against key economic, environmental, and social indicators. The core of SIMPLAN is formed by the RLM and MSM modules. This paper discusses only the calibration of the RLM and MSM for a base year (2001) for the city of Ahmedabad, India. Applications of TAM and ASM to Ahmedabad are discussed in separate papers and not reported here. However, a schematic diagram showing the interrelationship between the four modules is included. SIMPLAN is developed in a spreadsheet environment, with all key operations controlled by a visual interface using subroutines written in Visual Basic Application code. This creates a user-friendly graphical interface that makes the model simple to understand and operate by local planning agencies, and, in addition, provides them with the flexibility of updating the model as and when new data are available or a new round of the census is conducted.

Cambridge Futures: Forecating the Effect of Congestion Charging on Land Use and Transport

This chapter tests a congestion charging scheme for Cambridge using a MEPLAN land-use transport model combined with a SATURN traffic model. The scheme would include a daily toll for drivers crossing a cordon around the edge of the city and a lower charge for residents driving entirely within the cordon. The congestion charge would dramatically reduce the number of cars entering the city and improve traffic conditions. However, the charge would result in higher property prices as higher-income groups would displace lower socioeconomic groups by outbidding them to move into the city in order to avoid paying the cordon charge. This would increase the cost of living and employers’ production costs, and some employers would move out of the city, especially those in the retail and service sectors. The revenue raised and environmental benefits might be insufficient to compensate for the negative impacts on the local economy and the social equity. Cambridge Futures then tested the congestion charging scheme in combination with transportation investments. These would include expanding the public transit system and creating an orbital road outside the cordon linking the park-and-ride sites together and making it easier for through-traffic to bypass the city. This combination of road user charging with transportation improvements has a synergistic effect, making areas outside the city more accessible, and reducing average rents by facilitating more residential dispersal.

The Sao Paulo Metropolitan Study: A Case Study of the Effectiveness of Urban Systems Analysis

In 1974 the Local Authorities of Sao Paulo were faced with the difficult decision of either stopping the construction of the underground or stopping the construction of a system of urban motorways. They could no longer afford to finance the construction of both facilities. Also some doubts were expressed at that time about the advisability of building car-oriented facilities with the emerging energy crisis. The mayor, at that time Mr. Colasuono, suspended the construction of an important sunken motorway (Paulista), and issued an order to bury the foundations and to pave a normal arterial highway on top. The decision to build the underground was taken in the late 1960’s and the plan is illustrated in Figure 1. By 1974, the cost of building it had escalated considerably, with an estimated cost of over US