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Routing server

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Average road speed "shrinking window"
== Average road speed "shrinking window" ==
If there are enough recorded speeds on a road, then Waze uses a shrinking window of speeds to better estimate the average speed at the time you are travelling on it. Waze uses the speed of each road segment (in both directions) in intervals as small as 30 minutes. So a two-way road might have up to 96 average road speeds. We can assume that when there are insufficient records for an individual time slot, a wider time range is takes used (up to a full day). As the road is driven more, the time slot shrinks down to 30 minutes.
We can speculate that there is additional information used that is based upon the day of the week. There is some observational evidence that a road that is busy on weekdays and not used for routing is chosen as the optimal route on weekends.