VISCAL (VISSIM calibration) is an automated calibration tool for microscopic simulation parameters in VISSIM environment, based on three heuristic optimization algorithms: (a) genetic algorithm (GA); (b) simultaneous perturbation stochastic approximation (SPSA); (c) simulated annealing (SA). It is developed with a goal to automate and ease the tedious process of calibration, offering greater flexibility to the users by providing control on every aspect of the calibration process. It includes multiple features for a generic application tool with the ability to test the significance of the appropriate decision parameter set for a particular network, to determine the most suitable objective function to reflect network characteristics, and to check the suitability of any of the three heuristic optimization algorithms for a particular network. VISCAL also offers four objective function choices into the system: (1) speed, (2) flow, (3) delay, and (4) multi-objective criteria. It is able to calibrate all the driving behavior parameters for any type (urban, rural) and extent of network (small or large network). However, for this study, the operation of the tool is tested by a dataset obtained from a 3. 26 km freeway of Dhaka, Bangladesh.