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A comment on Waymo robotaxi hits a child near an elementary school in Santa Monica. Parent comment

Re:Waymo robotaxi hits a child near an elementary school in ... by sandworm101 on Thursday January 29, 2026 @02:10PM (#46814992)
A 25mph school zone? That seems fast. 15mph would be more the norm, which is in line with the 17mph the car believed itself to be traveling.

FYI, unless you are a commerical truck, a cop, or a racer, your speedometer will read slightly fast, sometimes as much as 5 to 10%. This is normal practice for cars as it limits manufacturer liability. You can check this using independant gps, ie not an in-dash unit. (Just imagine the court cases if a speedo read slower than the actual speed and you can understand why this started.)

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Re:Waymo robotaxi hits a child near an elementary school in ... by lkbm on Thursday January 29, 2026 @02:36PM (#46815402)
I mostly see 25 mph for school zones, though I'm in NC. Checking California, it sounds like 25 is standard there as well.[0] Some will drop to 15, but 25 is the norm as far as I can find.

[0] https://www.dmv.ca.gov/portal/handbook/california-driver-han...

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Re:Waymo robotaxi hits a child near an elementary school in ... by 0xffff2 on Thursday January 29, 2026 @02:45PM (#46815525)
I've lived all over California and I agree that 25mph is the norm here.

Edit: However, elsewhere in the thread someone linked this Streetview image that shoes that this particular school zone is 15mph: https://maps.app.goo.gl/7PcB2zskuKyYB56W8?g_st=ac

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Re:Waymo robotaxi hits a child near an elementary school in ... by thfuran on Thursday January 29, 2026 @08:08PM (#46819338)
25 mph is typical non-school-zone residential around here, with school zones always slower.
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Re:Waymo robotaxi hits a child near an elementary school in ... by tastyfreeze on Thursday January 29, 2026 @02:34PM (#46815359)
Also, a different wheel diameter than the speedometer was calibrated with and you will have a larger difference between actual velocity and speedometer reading. The odometer will also not record actual distance traveled.
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Re:Waymo robotaxi hits a child near an elementary school in ... by sandworm101 on Thursday January 29, 2026 @05:44PM (#46817885)
It depends. I had a honda motorcycle where the speedo was 10ish % fast (not unussual on bikes due to tire shape) but the odo was accutrate. Same sensor, but the computer just counted wheel rotations slightly differently for each use.
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Re:Waymo robotaxi hits a child near an elementary school in ... by TylerE on Thursday January 29, 2026 @06:55PM (#46818682)
Virtually all speedos read fast. The federal standards have a fairly high margin for being allowed to read high, and a zero margin for reading low. Thus speedos are more or less universally calibrated to read at least 5% high.
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Re:Waymo robotaxi hits a child near an elementary school in ... by cardiffspaceman on Thursday January 29, 2026 @02:49PM (#46815588)
In Encinitas, California, that sign would have no more than 20 MPH. In adjacent Carlsbad, I believe 25 is normal.
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Re:Waymo robotaxi hits a child near an elementary school in ... by loeg on Thursday January 29, 2026 @05:59PM (#46818069)
It does seem fast to me -- school zones are 20 mph in Seattle, at least when children are present. But Google suggests 25 is the norm in Santa Monica, where the incident occurred.
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