Validation of MFD-based models with microscopic simulations on real networks: Importance of production hysteresis and trip lengths estimation
Résumé
This work focuses on the application of so-called accumulation-based and trip-based MFD approaches to real transportation networks and discusses the calibration of the MFD shape and trip lengths estimation using a thorough validation of the network dynamics with micro-simulation data. As network state observations are often scattered close to the saturation, this work not only investigates a classical unimodal approach to fit the production MFD, but also a bimodal MFD curve. A method to integrate the production hysteresis into the MFD-based approach is briefed. Different methods of calibrating trip lengths in the reservoir are introduced to study the influence of trip lengths estimation on the accuracy of MFD models. MFD models are validated against micro-simulations that are carried out using the real OD matrix and demand that are estimated from the data of Lyon city in France. Two different scenarios namely, a free flow scenario and a network saturation scenario are considered to study the influence of calibration of production hysteresis and trip length estimation. The proposed bimodal production MFD curve captures the hysteresis in the production MFD to a good extent. Following, it is shown that the refined description of trip lengths gives more accurate estimates of accumulation evolution for the trip-based approach, whereas a single trip with mean trip length produces good evolution of state variables in accumulation-based model. Finally, a test case is presented with a modified OD matrix to study the effect of OD matrix changes on accuracy of MFD simulations.