Uncertainty Analysis of a Combined Travel Demand Model

Abstract:

Travel demand forecasts are subject to great uncertainties.A systematic uncertainty analysis provides insight into the level of confidence in the model outputs,and can lead to identification of the critical sources of uncertainty.An uncertainty analysis is made of a combined travel demand model (CTDM) with the sensitivity-based analytical method(SAM).The CTDM,on the basis of a single unifying rationale,is formulated as a nonlinear programming problem,and the sensitivity analysis is also made.The uncertainty analysis includes both input uncertainty and parameter uncertainty.The SAM,which requires less computational effort than sampling-based method in the uncertainty analysis,can obtain similar accuracy and can investigate the input uncertainty and parameter uncertainty separately.In order to improve credible level of outputs,to increase the accuracy of parameters is more effective than that of inputs.