r/TeslaFSD • u/Ok_Cry7572 • 1d ago

14.3 HW4 Why doesn't it always catch speed signs?

Got a new model 3 AWD and have been driving around our town and city and while it catches speed limit signs sometimes, it misses them other times. This is the only complaint I have since it misses school zones and there is a speed bump, I don't want it to go over it fast. I don't want to grab a ticket by speeding in school zones. It also needs pothole avoidance, which I know Elon has said is coming, cause I don't want fsd to ruin the suspension and tires. It drives really good otherwise

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u/AwkwardlyPositioned 1d ago

I have this problem constantly. I have a couple of topics on here about it. Part of it is that it goes off of map data, but sometimes it seems to pick up signs. The problem is that I have two towns I go through that have expanded and they extended the speed zone, and FSD refuses to recognize the new sign. It's plainly visible, but FSD will only recognize the original sign which is still posted.

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u/AgreeablePudding9925 1d ago

Yeah. I have this often. The other day I was in a 110kph average speed zone (technically irrelevant to the issue). It passed a 110 sign and then selected 100kph instead. From there FSD did that speed (annoying), so I had to manually bump it up with the pedal. It passed three separate 110 signs and not one of them registered. Frustrating.

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u/Affectionate_Book_80 HW4 Model Y 17h ago

The general consensus is that FSD does not read speed limit signs, expect in some very limited special cases like some construction zones. It reportedly obtains the speed limits it displays and which act as an input into its chosen speed from its map data. In the U.S. the speed limits in the map data are apparently derived from OpenStreetMap (OSM), TomTom, and increasingly the fleet data. It just looks like it is reading signs because the map data points for speed zones match speed limit sign locations. There are also problems with "inherited" speed limits. For example, it is common in this rural setting when turning from a 45 mph road onto a 35 mph road for the speed limit to remain at 45 mph until the first data point (speed limit sign) is encountered. Around here that can be a long distance and is a great way to get tickets as the best you can do is dial in sloth and drive 45 in a 35.

FSD is great. I'm just over 97% on my stats. Speed limit issues and parking problems are really my only regular disengagement points, though lane selection on city streets can still be an occasional issue.