And why does it always seem to under-estimate my commute time?
In: Engineering
>And why does it always seem to under-estimate my commute time?
Because you drive slower than the average person.
Its calculating your ETA on distance, and other drivers times and traffic. The one thing its not taking in to consideration (yet) is your own driving habits.
A mixture of dead reckoning – _distance to travel divided by average speed of method chosen_ – and billions of data points gathered from phones that have travelled on that route at that time before and that are travelling it now – _on Tuesday mornings a car usually takes X minutes to go from point A to point B when there are this many phones along the route_.
Most mapping software these days will be aware of what the speed limit on every road is between you and your destination. From there, its partially just math. You want to get to your destination as quickly as possible and so it will calculate several different routes to your destination, figure out the average speed across that path based on speed limits, and return whichever route gets you there fastest. This wont always be the shortest path, since the shortest path might involve driving through slow neighborhoods instead of major arterial roads.
It is also aware of every route every user has taken through their app and how long that trip took. This is how it can do traffic detection. If there’s a lot of people using there maps moving slowly through an area, theres probably a traffic jam. It can use this aggregated data to give better estimates than just pure speed limits since most drivers aren’t going the speed limit anyways.
If your always taking longer to get to your destination, its likely that you are a defensive driver who tends to drive at or below the speed limit.
ETA stands for Estimated time of arrival. The keyword here is estimated
They can’t possibly know how fast you are driving, immediate traffic conditions, detours etc
The estimation given is based on average results of that particular route
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