A meta-analysis of two Gauteng stated preference data sets

Abstract

Mode choice modelling is commonly done to estimate the patronage demand of the various available transport modes. Since the late 1990’s in South Africa, Stated Preference (SP) surveys and occasionally Revealed Preference (RP) surveys have been used to estimate the representative trip utility attributes and their associated weightings. The transit utility attributes and weightings are also used in the transit assignment process. Two analysis techniques that are commonly used for this estimation are Conjoint Analysis (CA) and Discrete Choice Models (DCM). Given the theoretical and practical differences between the techniques, their results are expected to be different, which has implications for their use in forecasting. This paper compares conjoint-based and DCM models as well as derived measures of willingness to pay such as the Value of Travel Time Savings (VTTS) to provide insight into their relative applicability in the SA context. We do this by re-analysing two metropolitan SP data sets, undertaken in Tshwane (2010) and Ekurhuleni (2013), on which conjoint-based choice models were developed in multi-modal environments that included the private car, taxi, bus and train modes. In both cases the alternative mode was the proposed Bus Rapid Transit (BRT) systems that were being planned in these metros. The paper concludes that discrete choice based models are more appropriate for the estimation of mode choice behaviour.