Calibration of VISSIM for Freeway Work Zones with Time-Varying Capacity

This paper presents a systematic procedure for calibration of a VISSIM model to replicate time dependent capacity, speed, and queue length for a 2-to-1 freeway work zone. The procedure models time dependent capacity by specifying time varying desired speed distributions while car following parameters have default values. Then it calibrates two car following parameters, CC0 (stand still distance) and CC1 (headway time), to reproduce speed and queue length, and it checks the resulting capacity values (i.e. departure rates) with those from field data. The analyses showed that if field speed data is input for desired speed distribution, VISSIM does not reproduce the data for single-lane freeway work zones. Thus regression models were developed to guide users how to determine the input parameters of desired speed distribution. In addition, results showed that different values of CC1 and CC0 could be chosen to replicate flow rate, speed, and queue length data. Among these values, lower CC1 values must be coupled with higher CC0 value (and vice versa) in order to produce field data.