Dani Broitman

Residential density change: Densification and urban expansion

Abstract The development of residential areas over time is a complex process that is characterised by substantial spatial and temporal variation. In essence, residential growth processes lead to two types of development: the construction of new housing units within existing residential areas (densification) or the development of new residential areas on land that was formerly open (expansion). This paper aims to understand the dynamic balance between these two processes and does so by analysing local changes in housing stock over time. The analysis is carried out for urban areas in the Netherlands, a country where urban concentration ambitions were adjusted in recent years. This changing planning context adds to the uncertainty about future residential development processes. Using detailed geographical data about land use and residential densities from 2000 onwards we study residential development and density changes in relation to prevailing spatially explicit policies. The observed changes are statistically linked to geographic and policy variables, such as the availability of developable land and the presence of restrictive or stimulating spatial policies. Residential densification is shown to occur in almost all regions of the country and is generally lower when demand for new dwellings is high and a limited amount of land is available within cities. Residential development zones are influential in shifting pressure from city cores while prescribing relatively high densities in expansions. At the local level we observe great variation in residential density development, but we find that densities increase within designated urban development zones and areas that rich in amenities. Restrictive planning regulations related to natural and landscape values tend to limit residential densities, as do initial high densities.

Cities in competition, characteristic time, and leapfrogging developers

In a recent paper Czamanski and Roth (2011 Annals of Regional Science 46 101–118) demonstrated that, because the profitability of construction projects is influenced by variations in the time incidence of costs and revenues, despite declining willingness to pay and land gradients with distance from central business districts, profitability can experience local maxima away from urban centers. The time until the realization of revenues was termed ‘characteristic time’. Its size is the result of planning polices and can lead to leapfrogging and scattered development, especially when interest rates are low or negligible. We explained this result by modeling the simple behavior of developers in the context of a single linear city. In this paper we consider the case of two municipalities with different development policies and characteristic time functions. We explore local maxima in profitability, typical of disequilibrium situations, especially during periods when cities are growing. Myopic assumptions, in the sense that each city is interested only in what happens on its side of the municipal boundary, can easily lead to unintended leapfrogging. Competition between cities can result in intentional leapfrogging or in spatially concentrated development, depending on the policy objectives. We extend the analysis further and consider qualitatively different cities that give rise to different gravity-type forces and differences in willingness to pay. The demand and supply sides of the building market are integrated into the model. The additional considerations can lead to various patterns of scattered development capable of explaining the spatial structure of metropolitan areas.

Analysing and simulating urban density: Exploring the difference between policy ambitions and actual trends in the Netherlands

This chapter explores the potential of geospatial analysis to characterize land use dynamics in urban areas and the surrounding urban fringe. It focuses on the difference between policy ambitions and reality with respect to urban densification. Policy ambitions for the containment of urban development are ambitious in the Netherlands, as is evident from the many local objectives to concentrate residential development within existing urban areas. These ambitions are formulated as target shares of the total net increase in housing stock that should be realized within designated urban area boundaries. Following a GIS-based analysis of local changes in housing stock between 2000 and 2008, we are able to describe actual intensification shares and residential densities in newly-developed urban areas. We observe that, especially in the already densely-populated western part of the country, the realized urban intensification shares are below the specified policy goals/ambition levels. Using these observations along with scenario-based projections of the regional increases in housing stock, we are able to determine the demand for new urban land in 2020. Using a land use simulation model, we simulate the urban development processes until 2020 according to two scenarios and two policy alternatives. In the first policy alternative, growth in the number of house units is based upon policy ambitions, while in the second scenario growth is based upon observed trends over the past decade. The results show that current policy ambitions related to urban intensification levels will greatly help in containing the substantial urban growth that is projected in the case of a high economic and population growth scenario. If urban development follows past trends, unabated, thus demonstrating relatively low urban intensification shares, large-scale urban extensions are likely to occur.