Sensitivity-based uncertainty analysis of a combined travel demand model

•Quantitative uncertainty analysis of a combined travel demand model.•The combined model overcomes limitations of the sequential four-step procedure.•Analytical sensitivity-based method requires less computation efforts than sampling method.•Uncertainties stemming from inputs and parameters can be treated separately.•Individual and collective effects of uncertainty on outputs can be quantified.

Travel demand forecasting is subject to great uncertainties. A systematic uncertainty analysis can provide insights into the level of confidence on the model outputs, and also identify critical sources of uncertainty for enhancing the robustness of the travel demand model. In this paper, we develop a systematic framework for quantitative uncertainty analysis of a combined travel demand model (CTDM) using the analytical sensitivity-based method. The CTDM overcomes limitations of the sequential four-step procedure since it is based on a single unifying rationale. The analytical sensitivity-based method requires less computational effort than the sampling-based method. Meanwhile, the uncertainties stemming from inputs and parameters can be treated separately so that the individual and collective effects of uncertainty on the outputs can be clearly assessed and quantified. Numerical examples are finally used to demonstrate the proposed sensitivity-based uncertainty analysis method for the CTDM.