I’ve been surprised that the nav screen on a 2019 F-150 knows where the speed limit change occurs within a few yards/meters [even if it gets the speed limit wrong because it was recently chopped by 5 mph - it’s apparently not reading the value on the sign].
“I’ve been surprised that the nav screen on a 2019 F-150 knows where the speed limit change occurs within a few yards/meters [even if it gets the speed limit wrong because it was recently chopped by 5 mph - it’s apparently not reading the value on the sign].”
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GIS (Geographical Information System) data is the mapped spatial data residing in your current software that upon receiving positional (GPS/GNSS) information your navigation software “understands” precisely where you are located by comparing current location to the entered (humans enter the recent available speed limit boundaries when building/updating the GIS) speed zone boundaries. In a word...briefly
Speed limit information is built into the GPS maps. My Garmins have had this same feature since my first one around 2008.
The GPS uses this speed limit information to help calculate estimated arrival times based on the route chosen.
I've noticed that when a speed limit changes along a stretch of road, the Garmin or built-in GPS will show the incorrect speed limit. This is usually corrected with the next map update.