Environment and Planning A: Economy and Space

This paper uses a joint-choice logit model of travel demand and residential location to simulate the impact of urban rapid-transit investment on housing values within a radial corridor. The model developed is a clean break with the traditional urban economic theory. Instead the heterogeneous nature of travel and location decisions is recognized and the logit model, consistent with stochastic utility maximization, is employed. Simulation experiments reveal that the aggregate increase in property values caused by transit's impact on work trips is highly sensitive to the aggregate number of vacancies within the corridor. Under reasonable assumptions, transit investment tends to lower central-city property values, to increase central-city vacancies, and to raise suburban property values. It tends to help the poor move further away from the center and penetrate the inner suburbs. Depending on several influences, aggregate property values can increase or decrease and the change can often be statistically insignificant. Calculations show that an equitable taxation (and compensation) of property-value changes may raise a small to modest proportion of a transit system's construction cost. Several considerations suggest that even these modest estimates might be optimistic. These results help develop an improved perspective on ‘value-capture policy’ which has not, up to now, benefited from quantitative analysis. Major extensions of the model are briefly considered.

The geography of farm-size variation has tended to overlook the relationships between physical size and agricultural productivity. This paper remedies that deficiency by explicitly considering the mechanisms promoting viability across the spectrum of farm-size gradation. Aspects of internal and external economies of scale, interfarm competition, local comparative advantage, and spatial separation are incorporated in a conceptual framework developed for a Canadian Prairie setting (Manitoba). In addition, social and cultural influences on the farm-size determinants are monitored. An equation system is established consisting of three structural equations, one each for large farms, medium-size farms, and small farms, and is calibrated by using two-stage least-squares regression. Results indicate that regional factors tend to overshadow the indices of economies of scale, but that efficiency considerations vary according to the size of farm.

Residential length of stay, or alternatively the turnover of families in a residential area, is expressed in terms of a distributed-lag model. The parameters of the rational form of the distributed-lag model are estimated from cross-sectional data via a nonlinear maximum-likelihood procedure reported by Nelson and Schwert (1974). The empirical application is based upon data provided by Marshall (1971), and the accuracy of the distributed-lag model in terms of predicting the number of families leaving is compared with the results from Marshall's fitted probability distributions. The usefulness of the distributed-lag model for simulation and control analyses is noted.

This report reviews recent papers which argue that urbanization trends in the US show a reversal of past patterns. The review suggests that a reversal is not obvious and may simply appear as a result of a statistical artifact: urbanization which has spilled over metropolitan boundaries may simply be more of the same outward growth but would show up as a metropolitan-to-nonmetropolitan growth shift. A new data file for eighteen other developed countries is examined. These data are suitable for computations of various versions of the Hoover index of population concentration. Such calculations suggest that the eighteen countries examined are experiencing more traditional urban outward expansion. This adds to scepticism of the reversal or ‘clean break’ hypothesis.

Quadratic assignment models and linear-programming models have been proposed for land-use plan design. The models represent transportation and divisibility of production differently and have solution algorithms with very different properties, but the most important distinction is that quadratic assignment models can handle externalities whereas linear models without integer side conditions cannot. Therefore quadratic models are useful for plan-making in response to externalities problems, whereas linear models can be used only for plan-making in response to dynamics problems.

An attempt is made to clarify some of the confusion about the notion of accessibility by examining the limitations, strengths, and conceptual bases of distance, topological, gravity, and cumulative-opportunity measures of accessibility. In their aggregate and disaggregate states the measures are practical, enabling measurement into the future and measurement with a minimum of data, but the assumptions that all nodes are potential destinations and that all origins are known severely restrict the meaning and uses of the measures. Time—space measures of accessibility do not make these assumptions although they are data hungry, retrospective, and share with the other measures the narrow conception of accessibility as a property of the built environment. It is proposed that accessibility be thought of as a vacancy in an activity routine and that it be measured in terms of the disruption involved in creating it.

A stochastic model for the development of spatial patterns is introduced and used to investigate the process of housing deterioration in an American city. Space is treated as a sequence of discrete locations and a spatial-lag structure is incorporated in the model by defining multivalued random variables whose values indicate conditions at a central location and at a series of spatial lags. The possible combinations of these values define the states of a Markov process, and a description of this process can be obtained by estimating probabilities for the transitions from state to state. Qualitative inferences about the effects of a process on existing spatial patterns are obtained by comparing an initial distribution, for the multivalued random variables, with the limiting distribution implied by the process description. Application of the model involves selection of an appropriate random variable as well as estimation of a set of transition probabilities. Results for Indianapolis in 1977 indicate that the probability of housing deterioration is strongly associated with the presence of deteriorated structures in nearby locations.

In the literature on cognitive maps, studies of the cognitive representations of specific areas are common. Much less adequately represented are mental maps of general applicability to a diversity of specific areas. In an attempt to adduce such general rules of the cognitive organization of space, two case studies of the North American city are discussed. The first involves student expectations of land-use geography and reveals strong senses of residential segregation and the clustering of commercial land use. The second examines the social geography of the city, constructed on the basis of expectations of the social and neighborhood characteristics of four housing groups: central-city renter, central-city owner, suburban renter, and suburban owner. Although the general rules revealed are reasonable, the contribution of the central-city apartment dweller to metropolitan social geography is seen as quite exceptional.

An earlier paper (Webber and Joseph, 1978) proposed a model of the process whereby messages diffuse between a system of cities and provided a means of approximating the solution to that model if cities can ‘self-infect’ themselves with the message. This paper continues the analysis of this model by investigating the case in which a city cannot send the message to itself. The analysis is numerical, and an alternative to Monte Carlo simulation is used. The results indicate that the diffusion process described by the model is highly predictable if information on the accessibility of cities is available. A second part of the paper shows that the approximation used in the earlier paper provides a reasonable description of the model solution for at least some parameter values.