The speed distribution curve in Vissim is set to represent the speed distributions from the collected field data. The posted speed limits are defined as 85 percent of the desired speed distribution in Vissim. Maximum speed distributions is recommended to be set no greater than 10 mph above the speed limit and no less than 5 mph below the speed limit. When calibrating speed distributions, it is possible to increase the percentage of vehicles traveling at the speed or the maximum speed limit cap based on field data.