Calibration of CORSIM models under saturated traffic flow conditions.

PDFTech ReportMicroscopic traffic flowCalibrationAlgorithmsPerformance measurementTraffic modelsTravel patternsBehaviorMicrosimulationSaturation flowTraffic simulationUnited StatesUniversity of Nevada, Las Vegas. Transportation Research CenterPaz, AlexanderMolano-Paz, Victor HugoUniversity of Nevada, Las Vegas. Transportation Research CenterNevada. Dept. of TransportationUniversity Transportation Centers Program (U.S.)US Transportation CollectionThis study proposes a methodology to calibrate microscopic traffic flow simulation models.The proposed methodology has the capability to calibrate simultaneously all the calibrationparameters as well as demand patterns for any network topology. These parameters include global andlocal parameters as well as driver behavior and vehicle performance parameters; all based on multipleperformance measures, such as link counts and speeds. Demand patterns are included in thecalibration framework in terms of turning volumes. A Simultaneous Perturbation StochasticApproximation (SPSA) algorithm is proposed to search for the vector of the model\ue2\u20ac\u2122s parameters thatminimizes the difference between actual and simulated network states. Previous studies proposedsimilar methodologies; however, only a small number of calibration parameters were considered, andnone of the demand values. Moreover, an extensive and a priori process was used in order to choosethe subset of parameters with the most potential impact.In the proposed methodology, the simultaneous consideration of all model parameters andmultiple performance measures enables the determination of better estimates at a lower cost in termsof a user\ue2\u20ac\u2122s effort. Issues associated with convergence and stability are reduced because the effects ofchanging parameters are taken into consideration to adjust them slightly and simultaneously. Thesimultaneous adjustment of all parameters results in a small number of evaluations of the objectivefunction. The experimental results illustrate the effectiveness and validity of this proposedmethodology. Three networks were calibrated with excellent results. The first network was an arterialnetwork with link counts and speeds used as performance measurements for calibration. The secondnetwork included a combination of freeway ramps and arterials, with link counts used as performancemeasurements.Considering simultaneously arterials and freeways is a significant challenge because the twomodels are different and their parameters are calibrated at the same time. This represents a highernumber of parameters, which increases the complexity of the optimization problem. A proper solutionfrom all feasible solutions becomes harder to find. The third network was an arterial network, withtime-dependent link counts and speed used as performance measurements. The same set of calibrationparameters was used in all experiments. All calibration parameters were constrained within reasonableboundaries. Hence, the design and implementation of the proposed methodology enables thecalibration of generalized micro-simulation traffic flow simulation models