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Did I fix phantom braking on the NJTP?


Sep 20, 2018
So earlier this year I was southbound on the NJTP in cars/truck/busses using nav on AP, and the car suddenly reduced speed to maybe 50 mph from probably 70 mph. That was annoying. Then it happened again a few miles later, wtf. Whatever. Later in the summer I was on the same stretch of road, and voila, it happened again, in I think the same spot.

There is a theory (Is Tesla using OSM via MapBox, Valhalla? / Questions and Answers / OpenStreetMap Forum) Tesla is using OpenStreetMap for speed limit data, and if it’s missing, it defaults to 45 mph, explaining at least some phantom braking. I followed the OSM track down the NJTP and sure enough there is a bridge over Mill Lane West road near Columbus that the speed limit data was missing from in the cars/trucks/busses lanes. So I fixed it...

If Tesla really is getting speed limits from OSM, I’m not sure how long it takes for changes to propagate (I’ve heard 6 months, and I’ve heard instant). I’m not on the NJTP often enough to test if it worked myself; can a regular corroborate my experience, localize it specifically to the Mill Lane West road bridge, or tell me if it is fixed?

If it’s true, this is an easy fix for phantom braking, once people know about it.

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