A simulation study was conducted as part of a recently completed research project aimed at determining relationships between weaving length, speed, and overall vehicle operations on Texas freeways. The VISSIM microscopic traffic simulation model was used to analyze various ramp spacing and traffic condition scenarios that could otherwise not be observed in the field. The combination of five ramp spacing scenarios, three design speeds, four freeway and ramp volume levels and six origin and destination (O-D) percentages were considered. The model was calibrated using volume, speed and lane changing data from field measurements and video recordings obtained on freeway segments in Houston and Dallas, Texas. It was found that observed vehicle speeds and lane changes could not be replicated using a single parameter set. Field observations revealed that lane changes are not uniformly distributed along the entire length of weaving segment between entrance and exit ramps. It was also observed that vehicles entering the freeway within the first 250 ft, generally accepted shorter gaps to perform their desired lane changes than exiting vehicles did. To replicate these lane changing patterns, four parameter sets representing different degrees of driver aggressiveness (relaxed, normal, moderately aggressive and aggressive) were determined and distributed longitudinally along the weaving section. They were applied to different segments between the entry and exit gores. The simulations using these spatially distributed parameter sets replicated observed speeds and lane changes better than initial simulations using a single parameter set for the entire weaving segment.