Univariate Uncertainty Analysis of an Integrated Land Use and Transportation Model: MEPLAN

Land use and transportation models are typically given precise inputs and return precise outputs. This precision should not be mistaken for accuracy. The purpose of this paper is to introduce uncertainty into three inputs and one parameter of a fully integrated land use and travel demand model -- MEPLAN -- to determine the effect of uncertain inputs on model outputs. Inputs were selected based upon there being expected sources of uncertainty. Inputs were varied individually based upon plausible amounts of error and the marginal impact of each on outputs was examined. Counter to the findings of previous similar studies, uncertainty in the socio-economic forecasts did not dominate the final amounts of error observed in the model outputs. The propagation of error across model years, as well as the final level of error in the end-year, is examined.