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

The authors report the development and calibration of a Lowry model with mu ltiple 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 pop ulation 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 ge nerates 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 c oefficients associated with the travel impedance function for different mar ket segments. In the second stage, the relationships between the calibrated potentials and various land-use variables are investigated by means of a m ultivariate stepwise regression analysis. The significant land-use variable s are identified and equations relating these variables to the potentials f or each category of population and employment are established. The third st age is model refinement, in which the model parameters obtained from the fi rst two stages are fine-tuned to reduce further the discrepancy between the observed and modeled distributions of population and employment. A case st udy of Hong Kong is presented to illustrate the effectiveness of the propos ed methodology.