Demographic and regional economic modeling using stochastic allocation in the City of Johannesburg

Abstract

The paper describes a method for the modelling of demographic and economic change at a spatially disaggregate level that is compatible with the requirements of a conventional transport model. The method was developed and tested in the City of Johannesburg, South Africa, as part of a scenario planning exercise to assess potential land use and transport interventions. The procedure does not model behavioural processes explicitly, but incorporates the factors believed to influence the development of residential and non-residential land uses in a multi-criteria analysis framework, within the constraints of land availability and the guiding effects of government policy. Allocation occurs in discrete time-steps, allowing the dynamic evolution of outcomes to be modelled in a non-equilibrium framework. It operates in connected mode with the transport model, taking accessibility changes as input into subsequent land use allocations. It employs Monte Carlo simulation to approximate randomness in the location decision outcome, thus providing some sense of the variability of outcomes that may occur consistent with base year conditions, regional growth estimates, and a set of allocation criteria. The method is illustrated for the City of Johannesburg over a thirty-year planning horizon, and its particular strengths for application in a developing society are discussed.