The development and calibration of a Lowry model with multiple market segments

The authors report the development and calibration of a Lowry model with multiple market segments of population and employment, with use of Hong Kong as a case study. The model contains, for each zone and each category of population and employment, a population potential and an employment potential that measure the relative attractiveness of the zone in the study area with respect to residents' choice of home location and business setup (which generates employment opportunities), respectively. The calibration procedure comprises three stages. In the first stage, a genetic algorithm is employed to calibrate the population and employment potentials, together with the coefficients associated with the travel impedance function for different market segments. In the second stage, the relationships between the calibrated potentials and various land-use variables are investigated by means of a multivariate stepwise regression analysis. The significant land-use variables are identified and equations relating these variables to the potentials for each category of population and employment are established. The third stage is model refinement, in which the model parameters obtained from the first two stages are fine-tuned to reduce further the discrepancy between the observed and modeled distributions of population and employment. A case study of Hong Kong is presented to illustrate the effectiveness of the proposed methodology.