Desired Speed Data (Time mean speed (TMS) is the most important parameter describing the state of a given traffic stream. Collecting during the off-peak or free- flow conditions can help set the desired speed for that segment of the network. Spot speed data during peak periods can also provide data for the calibration process. The data should preferably be collected when there is no influence from weather, incidents, and/or other factors that may impede free-flowing traffic in the study area.