Period Speed (mph) Travel Time (s) Distance (ft) Speed Ratio # of Stops Stop% Stop Time (s) Speed Variance (Standard Deviation) Travel Time Index (TTI)The Travel Time Index is the ratio of the peak-period travel time to the free-flow travel time. Planning Time Index (PI)The planning time index represents how much total time a traveler should allow to ensure on-time arrival. It is the ratio of the peak-period travel time to the free-flow travel time. Buffer Index (BI)The buffer index represents the extra time (or time cushion) that travelers must add to their average travel time when planning trips to ensure on-time arrival. Speed Limit 55.0 423 34134 1 0 0% 0 All 40.6 583 34134 0.74 1.9 15.6% 64 5.9 1.38 1.58 0.15 Before After Difference Difference%