Environment and Planning B: Urban Analytics and City Science

In this paper comparisons of Dutch and British planning are drawn on to ask where to draw the line between flexibility and opportunism, using US zoning as an example. The characteristic of zoning is that it works with statements of intent which become effective only in guiding regulatory measures. US zoning is then analysed against the backcloth of legal rights in landed property and the land regime. It is found to be inflexible in theory.

But, even within the standard model of zoning, there is room for variances and for rezoning. So there are limited areas of discretion, and some of the burden of preparing of decisions is shifted onto applicants. Approaches introduced since have in common that definite decisions are delayed, and that the locus of decision shifts still further towards developers. Thus two perspectives on development are recognised: the broader one of the land regime embodied in the zoning ordinance, and a specific one taking the particular plot of land and its potential uses as its starting point.

The distinction between a flexible and an opportunistic decision cannot be whether preconceived plans are departed from. That is inevitable. Rather, that distinction has to do with how these two perspectives are related to each other. Opportunistic decisions fail to attend to wider implications of departures. They thereby create uncertainty over and above that which already exists. Flexible decisions update plans where these have become outdated. They form an essential element in a dynamic planning system.

Some of the discussions in two distinct areas of planning theory concern, namely the substantive versus procedural theory debate and the uncertain role concepts of planners, are related to each other. These concerns are considered from a practical viewpoint and some empirical data are used to raise important issues for planning practice. The viability of planning theory in Third World countries as either substantive issues alone or procedural issues alone is questioned. For educational purposes in the Third World, a wider spectrum of theories of planning can be useful for the advancement of planning.

Many common assignment algorithms are based on Dial's original design to determine the paths that trip makers will follow from a given origin to destination centroids. The purpose of this paper is to show that the rules that have to be applied result in two unwanted properties. The first is that trips assigned from an origin centroid i to a destination j can be dramatically different to those resulting from centroid j to centroid i, even if the number of trips is the same and the network is perfectly symmetric. The second is that the number of paths that are ‘accepted’ by the algorithm can be surprisingly small. Asymmetry can cause numerous problems in transport model applications. It will not only produce unrealistic results, but also, as is demonstrated here, makes convergence toward supply — demand equilibrium impossible. The paper describes the principles on which Dial-type algorithms are based, the way in which they affect the transport model structure, and how the unwanted characteristics arise. An alternative algorithm, based on a dispersion factor and multipath search is presented, pointing out the advantages, both theoretical and operational, and some difficulties. A simple network is used as an example throughout the paper, and references to real applications are made.

In examining the adaptability of various urban forms to events such as sudden oil shortages, or uncertainties in supply, it is important to distinguish between short-term adjustments and more durable medium-term and longer-term effects. Whereas short-term effects may just involve certain commuters changing their travel modes, medium-term effects include change of job, and longer-term effects include relocation both of household and of employment activity. Using certain geometric patterns of housing and jobs and certain assumptions about the form of the transport network, it is demonstrated that some arrangements allow more scope for medium-term adjustments than others. In the longer term, it is demonstrated that the degree to which commuters have already been able to make the medium-term adjustments of changing job determines whether a greater dispersion or a greater concentration of job opportunities will reduce average trip lengths. Last, possible implications of changing technology on the modification and even reversal of these changes in urban travel behaviour are discussed.

The entropy-maximising methodology for variables which take discrete values is used to derive the rank-size rule and to give a new interpretation of the constants. Relationships are found between the real populations of the cities, the populations that are given by the models, and the rank of the cities. A new index that represents the degree of concentration of a country is introduced as well as a new measure for the deviation of one pair of cities from the rank-size rule. The model is applied to data for Greek cities.

A previous issue of this journal included a paper called “SIRO-PLAN and LUPLAN: an Australian approach to land-use planning”. The approach is described here in more conventional plan-making and plan-evaluation terms and is observed to be inappropriate for the types of problems it is intended to solve, to incorporate a politically unacceptable design and selection procedure, to be oriented to plan-making rather than to decisionmaking, and to be unacceptably aloof from the community client. An approach to planning linking strategic problem solving to tactical zoning controls is advanced as an alternative.

This note replies briefly to a recent criticism of the SIRO-PLAN/LUPLAN approach to land-use planning which claims it to be politically regressive, closed to public participation, and inadequately representative of the sort of planning problems it is intended to assist with.

Although regional economic impact studies stop a long way short of providing economic evaluations of alternative uses of open space, they are valuable in quantifying tangible contributions of recreation and tourism to local economic activity. Such studies might be vital in supporting the case for conservation and national parks. Regional economic impact studies predict changes in output, income, and employment stemming from visitor expenditures. A review of the quantitative findings of twenty-nine such studies shows a surprising commonality in regional multiplier estimates in the range 1.25–1.89. This is despite wide diversity in the location, context, and methodology of the studies. The second section of the paper is a case study conducted in Cooloola National Park, Australia. Problems in measuring visitor expenditures are discussed in some detail, as it is argued that inaccuracies in this phase of research may be more significant than those arising from multiplier estimation. Markedly different impacts of day-trippers, campers, and commercial tour passengers were found in this area as a result of varying expenditures by visitors and their place of purchase. Campers are typically fully provisioned and contribute little to local business in comparison with commercial tour passengers who patronise local accommodation establishments. Park managers, by controlling access and use densities, choosing facilities and park infrastructure, and supervising visitor activities have a significant influence on the economic impact of a park. Capital investments and maintenance expenditures will also have economic significance to local employment creation and therefore to local economies and their politicians.